| `ASSERT_THROW(`_statement_, _exception\_type_`);`| `EXPECT_THROW(`_statement_, _exception\_type_`);`| _statement_ throws an exception of the given type |
`ASSERT_THROW(statement, exception_type);` | `EXPECT_THROW(statement, exception_type);` | `statement` throws an exception of the given type
| `ASSERT_ANY_THROW(`_statement_`);`| `EXPECT_ANY_THROW(`_statement_`);`| _statement_ throws an exception of any type |
`ASSERT_ANY_THROW(statement);` | `EXPECT_ANY_THROW(statement);` | `statement` throws an exception of any type
| `ASSERT_NO_THROW(`_statement_`);`| `EXPECT_NO_THROW(`_statement_`);`| _statement_ doesn't throw any exception |
`ASSERT_NO_THROW(statement);` | `EXPECT_NO_THROW(statement);` | `statement` doesn't throw any exception
Examples:
Examples:
```
```c++
ASSERT_THROW(Foo(5),bar_exception);
ASSERT_THROW(Foo(5),bar_exception);
EXPECT_NO_THROW({
EXPECT_NO_THROW({
...
@@ -70,79 +80,96 @@ EXPECT_NO_THROW({
...
@@ -70,79 +80,96 @@ EXPECT_NO_THROW({
});
});
```
```
_Availability_: Linux, Windows, Mac; since version 1.1.0.
**Availability**: Linux, Windows, Mac; requires exceptions to be enabled in the
build environment (note that `google3`**disables** exceptions).
## Predicate Assertions for Better Error Messages ##
### Predicate Assertions for Better Error Messages
Even though Google Test has a rich set of assertions, they can never be
Even though googletest has a rich set of assertions, they can never be complete,
complete, as it's impossible (nor a good idea) to anticipate all the scenarios
as it's impossible (nor a good idea) to anticipate all scenarios a user might
a user might run into. Therefore, sometimes a user has to use `EXPECT_TRUE()`
run into. Therefore, sometimes a user has to use `EXPECT_TRUE()` to check a
to check a complex expression, for lack of a better macro. This has the problem
complex expression, for lack of a better macro. This has the problem of not
of not showing you the values of the parts of the expression, making it hard to
showing you the values of the parts of the expression, making it hard to
understand what went wrong. As a workaround, some users choose to construct the
understand what went wrong. As a workaround, some users choose to construct the
failure message by themselves, streaming it into `EXPECT_TRUE()`. However, this
failure message by themselves, streaming it into `EXPECT_TRUE()`. However, this
is awkward especially when the expression has side-effects or is expensive to
is awkward especially when the expression has side-effects or is expensive to
evaluate.
evaluate.
Google Test gives you three different options to solve this problem:
googletest gives you three different options to solve this problem:
### Using an Existing Boolean Function ###
#### Using an Existing Boolean Function
If you already have a function or a functor that returns `bool` (or a type
If you already have a function or functor that returns `bool` (or a type that
that can be implicitly converted to `bool`), you can use it in a _predicate
can be implicitly converted to `bool`), you can use it in a *predicate
assertion_ to get the function arguments printed for free:
assertion* to get the function arguments printed for free:
| `ASSERT_PRED2(pred2, | `EXPECT_PRED2(pred2, | `pred2(val1, val2)` is true |
: val1, val2);` : val1, val2);` : :
| `...` | `...` | ... |
In the above, _predn_ is an _n_-ary predicate function or functor, where
In the above, `predn` is an `n`-ary predicate function or functor, where`val1`,
_val1_, _val2_, ..., and _valn_ are its arguments. The assertion succeeds
`val2`, ..., and `valn` are its arguments. The assertion succeeds if the
if the predicate returns `true` when applied to the given arguments, and fails
predicate returns `true` when applied to the given arguments, and fails
otherwise. When the assertion fails, it prints the value of each argument. In
otherwise. When the assertion fails, it prints the value of each argument. In
either case, the arguments are evaluated exactly once.
either case, the arguments are evaluated exactly once.
Here's an example. Given
Here's an example. Given
```
```c++
// Returns true iff m and n have no common divisors except 1.
// Returns true iff m and n have no common divisors except 1.
boolMutuallyPrime(intm,intn){...}
boolMutuallyPrime(intm,intn){...}
constinta=3;
constinta=3;
constintb=4;
constintb=4;
constintc=10;
constintc=10;
```
```
the assertion `EXPECT_PRED2(MutuallyPrime, a, b);` will succeed, while the
the assertion
assertion `EXPECT_PRED2(MutuallyPrime, b, c);` will fail with the message
```c++
EXPECT_PRED2(MutuallyPrime,a,b);
```
will succeed, while the assertion
```c++
EXPECT_PRED2(MutuallyPrime,b,c);
```
<pre>
will fail with the message
!MutuallyPrime(b, c) is false, where<br>
b is 4<br>
c is 10<br>
</pre>
**Notes:**
```none
MutuallyPrime(b, c) is false, where
b is 4
c is 10
```
1. If you see a compiler error "no matching function to call" when using `ASSERT_PRED*` or `EXPECT_PRED*`, please see [this FAQ](faq.md#the-compiler-complains-no-matching-function-to-call-when-i-use-assert_predn-how-do-i-fix-it) for how to resolve it.
> NOTE:
1. Currently we only provide predicate assertions of arity <= 5. If you need a higher-arity assertion, let us know.
>
> 1. If you see a compiler error "no matching function to call" when using
> `ASSERT_PRED*` or `EXPECT_PRED*`, please see
> [this](faq#OverloadedPredicate) for how to resolve it.
> 1. Currently we only provide predicate assertions of arity <= 5. If you need
> a higher-arity assertion, let [us](http://g/opensource-gtest) know.
_Availability_: Linux, Windows, Mac.
**Availability**: Linux, Windows, Mac.
### Using a Function That Returns an AssertionResult ###
#### Using a Function That Returns an AssertionResult
While `EXPECT_PRED*()` and friends are handy for a quick job, the
While `EXPECT_PRED*()` and friends are handy for a quick job, the syntax is not
syntax is not satisfactory: you have to use different macros for
satisfactory: you have to use different macros for different arities, and it
different arities, and it feels more like Lisp than C++. The
feels more like Lisp than C++. The`::testing::AssertionResult` class solves
`::testing::AssertionResult` class solves this problem.
this problem.
An `AssertionResult` object represents the result of an assertion
An `AssertionResult` object represents the result of an assertion (whether it's
(whether it's a success or a failure, and an associated message). You
a success or a failure, and an associated message). You can create an
can create an `AssertionResult` using one of these factory
`AssertionResult` using one of these factory functions:
functions:
```
```c++
namespacetesting{
namespacetesting{
// Returns an AssertionResult object to indicate that an assertion has
// Returns an AssertionResult object to indicate that an assertion has
| `ASSERT_NEAR(`_val1, val2, abs\_error_`);` | `EXPECT_NEAR`_(val1, val2, abs\_error_`);` | the difference between _val1_ and _val2_ doesn't exceed the given absolute error |
| `ASSERT_NEAR(val1, | `EXPECT_NEAR(val1, val2, | the difference between |
| `ASSERT_DEATH(`_statement, regex_`);` | `EXPECT_DEATH(`_statement, regex_`);` | _statement_ crashes with the given error |
`ASSERT_DEATH(statement, regex);`| `EXPECT_DEATH(statement, regex);`| `statement` crashes with the given error
| `ASSERT_DEATH_IF_SUPPORTED(`_statement, regex_`);` | `EXPECT_DEATH_IF_SUPPORTED(`_statement, regex_`);` | if death tests are supported, verifies that _statement_ crashes with the given error; otherwise verifies nothing |
`ASSERT_DEATH_IF_SUPPORTED(statement, regex);` | `EXPECT_DEATH_IF_SUPPORTED(statement, regex);` | if death tests are supported, verifies that `statement` crashes with the given error; otherwise verifies nothing
| `ASSERT_EXIT(`_statement, predicate, regex_`);` | `EXPECT_EXIT(`_statement, predicate, regex_`);`|_statement_ exits with the given error and its exit code matches _predicate_ |
`ASSERT_EXIT(statement, predicate, regex);`| `EXPECT_EXIT(statement, predicate, regex);` | `statement` exits with the given error, and its exit code matches `predicate`
where _statement_ is a statement that is expected to cause the process to
where `statement` is a statement that is expected to cause the process to die,
die, _predicate_ is a function or function object that evaluates an integer
`predicate` is a function or function object that evaluates an integer exit
exit status, and _regex_ is a regular expression that the stderr output of
status, and `regex` is a (Perl) regular expression that the stderr output of
_statement_ is expected to match. Note that _statement_ can be _any valid
`statement` is expected to match. Note that `statement` can be *any valid
statement_ (including _compound statement_) and doesn't have to be an
statement* (including *compound statement*) and doesn't have to be an
expression.
expression.
As usual, the `ASSERT` variants abort the current test function, while the
As usual, the `ASSERT` variants abort the current test function, while the
`EXPECT` variants do not.
`EXPECT` variants do not.
**Note:** We use the word "crash" here to mean that the process
> NOTE: We use the word "crash" here to mean that the process terminates with a
terminates with a _non-zero_ exit status code. There are two
> *non-zero* exit status code. There are two possibilities: either the process
possibilities: either the process has called `exit()` or `_exit()`
> has called `exit()` or `_exit()` with a non-zero value, or it may be killed by
with a non-zero value, or it may be killed by a signal.
> a signal.
>
This means that if _statement_ terminates the process with a 0 exit
> This means that if `*statement*` terminates the process with a 0 exit code, it
code, it is _not_ considered a crash by `EXPECT_DEATH`. Use
> is *not* considered a crash by `EXPECT_DEATH`. Use `EXPECT_EXIT` instead if
`EXPECT_EXIT` instead if this is the case, or if you want to restrict
> this is the case, or if you want to restrict the exit code more precisely.
the exit code more precisely.
A predicate here must accept an `int` and return a `bool`. The death test
A predicate here must accept an `int` and return a `bool`. The death test
succeeds only if the predicate returns `true`. Google Test defines a few
succeeds only if the predicate returns `true`. googletest defines a few
predicates that handle the most common cases:
predicates that handle the most common cases:
```
```c++
::testing::ExitedWithCode(exit_code)
::testing::ExitedWithCode(exit_code)
```
```
This expression is `true` if the program exited normally with the given exit
This expression is `true` if the program exited normally with the given exit
code.
code.
```
```c++
::testing::KilledBySignal(signal_number)// Not available on Windows.
::testing::KilledBySignal(signal_number)// Not available on Windows.
```
```
...
@@ -573,49 +714,63 @@ that verifies the process' exit code is non-zero.
...
@@ -573,49 +714,63 @@ that verifies the process' exit code is non-zero.
Note that a death test only cares about three things:
Note that a death test only cares about three things:
1. does _statement_ abort or exit the process?
1. does `statement` abort or exit the process?
1. (in the case of `ASSERT_EXIT` and `EXPECT_EXIT`) does the exit status satisfy _predicate_? Or (in the case of `ASSERT_DEATH` and `EXPECT_DEATH`) is the exit status non-zero? And
2. (in the case of `ASSERT_EXIT` and `EXPECT_EXIT`) does the exit status
1. does the stderr output match _regex_?
satisfy `predicate`? Or (in the case of `ASSERT_DEATH` and `EXPECT_DEATH`)
is the exit status non-zero? And
3. does the stderr output match `regex`?
In particular, if _statement_ generates an `ASSERT_*` or `EXPECT_*` failure, it will **not** cause the death test to fail, as Google Test assertions don't abort the process.
In particular, if `statement` generates an `ASSERT_*` or `EXPECT_*` failure, it
will **not** cause the death test to fail, as googletest assertions don't abort
the process.
To write a death test, simply use one of the above macros inside your test
To write a death test, simply use one of the above macros inside your test
function. For example,
function. For example,
```
```c++
TEST(MyDeathTest,Foo){
TEST(MyDeathTest,Foo){
// This death test uses a compound statement.
// This death test uses a compound statement.
ASSERT_DEATH({ int n = 5; Foo(&n); }, "Error on line .* of Foo()");
_Availability:_ Linux, Windows (requires MSVC 8.0 or above), Cygwin, and Mac (the latter three are supported since v1.3.0). `(ASSERT|EXPECT)_DEATH_IF_SUPPORTED` are new in v1.4.0.
**Availability**: Linux, Windows (requires MSVC 8.0 or above), Cygwin, and Mac
### Regular Expression Syntax
## Regular Expression Syntax ##
On POSIX systems (e.g. Linux, Cygwin, and Mac), Google Test uses the
On POSIX systems (e.g. Linux, Cygwin, and Mac), googletest uses the
syntax in death tests. To learn about this syntax, you may want to read this [Wikipedia entry](http://en.wikipedia.org/wiki/Regular_expression#POSIX_Extended_Regular_Expressions).
syntax. To learn about this syntax, you may want to read this
| `\\D` | matches any character that's not a decimal digit |
`\\d` | matches any decimal digit
| `\\f` | matches `\f` |
`\\D` | matches any character that's not a decimal digit
| `\\n` | matches `\n` |
`\\f` | matches `\f`
| `\\r` | matches `\r` |
`\\n` | matches `\n`
| `\\s` | matches any ASCII whitespace, including `\n` |
`\\r` | matches `\r`
| `\\S` | matches any character that's not a whitespace |
`\\s` | matches any ASCII whitespace, including `\n`
| `\\t` | matches `\t` |
`\\S` | matches any character that's not a whitespace
| `\\v` | matches `\v` |
`\\t` | matches `\t`
| `\\w` | matches any letter, `_`, or decimal digit |
`\\v` | matches `\v`
| `\\W` | matches any character that `\\w` doesn't match |
`\\w` | matches any letter, `_`, or decimal digit
| `\\c` | matches any literal character `c`, which must be a punctuation |
`\\W` | matches any character that `\\w` doesn't match
| `\\.` | matches the `.` character |
`\\c` | matches any literal character `c`, which must be a punctuation
| `.` | matches any single character except `\n` |
`.` | matches any single character except `\n`
| `A?` | matches 0 or 1 occurrences of `A` |
`A?` | matches 0 or 1 occurrences of `A`
| `A*` | matches 0 or many occurrences of `A` |
`A*` | matches 0 or many occurrences of `A`
| `A+` | matches 1 or many occurrences of `A` |
`A+` | matches 1 or many occurrences of `A`
| `^` | matches the beginning of a string (not that of each line) |
`^` | matches the beginning of a string (not that of each line)
| `$` | matches the end of a string (not that of each line) |
`$` | matches the end of a string (not that of each line)
| `xy` | matches `x` followed by `y` |
`xy` | matches `x` followed by `y`
To help you determine which capability is available on your system,
To help you determine which capability is available on your system, googletest
Google Test defines macro `GTEST_USES_POSIX_RE=1` when it uses POSIX
defines macros to govern which regular expression it is using. The macros are:
extended regular expressions, or `GTEST_USES_SIMPLE_RE=1` when it uses
<!--absl:google3-begin(google3-only)-->`GTEST_USES_PCRE=1`, or
the simple version. If you want your death tests to work in both
<!--absl:google3-end-->`GTEST_USES_SIMPLE_RE=1` or `GTEST_USES_POSIX_RE=1`. If
cases, you can either `#if` on these macros or use the more limited
you want your death tests to work in all cases, you can either `#if` on these
syntax only.
macros or use the more limited syntax only.
## How It Works ##
### How It Works
Under the hood, `ASSERT_EXIT()` spawns a new process and executes the
Under the hood, `ASSERT_EXIT()` spawns a new process and executes the death test
death test statement in that process. The details of how precisely
statement in that process. The details of how precisely that happens depend on
that happens depend on the platform and the variable
the platform and the variable ::testing::GTEST_FLAG(death_test_style) (which is
`::testing::GTEST_FLAG(death_test_style)` (which is initialized from the
initialized from the command-line flag `--gtest_death_test_style`).
command-line flag `--gtest_death_test_style`).
* On POSIX systems, `fork()` (or `clone()` on Linux) is used to spawn the
* On POSIX systems, `fork()` (or `clone()` on Linux) is used to spawn the child, after which:
child, after which:
* If the variable's value is `"fast"`, the death test statement is immediately executed.
* If the variable's value is `"fast"`, the death test statement is
* If the variable's value is `"threadsafe"`, the child process re-executes the unit test binary just as it was originally invoked, but with some extra flags to cause just the single death test under consideration to be run.
immediately executed.
* On Windows, the child is spawned using the `CreateProcess()` API, and re-executes the binary to cause just the single death test under consideration to be run - much like the `threadsafe` mode on POSIX.
* If the variable's value is `"threadsafe"`, the child process re-executes
the unit test binary just as it was originally invoked, but with some
Other values for the variable are illegal and will cause the death test to
extra flags to cause just the single death test under consideration to
fail. Currently, the flag's default value is `"fast"`. However, we reserve the
be run.
right to change it in the future. Therefore, your tests should not depend on
* On Windows, the child is spawned using the `CreateProcess()` API, and
this.
re-executes the binary to cause just the single death test under
consideration to be run - much like the `threadsafe` mode on POSIX.
In either case, the parent process waits for the child process to complete, and checks that
Other values for the variable are illegal and will cause the death test to fail.
1. the child's exit status satisfies the predicate, and
Currently, the flag's default value is
1. the child's stderr matches the regular expression.
"fast". However, we reserve
the right to change it in the future. Therefore, your tests should not depend on
If the death test statement runs to completion without dying, the child
this. In either case, the parent process waits for the child process to
process will nonetheless terminate, and the assertion fails.
complete, and checks that
## Death Tests And Threads ##
1. the child's exit status satisfies the predicate, and
2. the child's stderr matches the regular expression.
If the death test statement runs to completion without dying, the child process
will nonetheless terminate, and the assertion fails.
### Death Tests And Threads
The reason for the two death test styles has to do with thread safety. Due to
The reason for the two death test styles has to do with thread safety. Due to
well-known problems with forking in the presence of threads, death tests should
well-known problems with forking in the presence of threads, death tests should
...
@@ -707,35 +869,43 @@ arrange that kind of environment. For example, statically-initialized modules
...
@@ -707,35 +869,43 @@ arrange that kind of environment. For example, statically-initialized modules
may start threads before main is ever reached. Once threads have been created,
may start threads before main is ever reached. Once threads have been created,
it may be difficult or impossible to clean them up.
it may be difficult or impossible to clean them up.
Google Test has three features intended to raise awareness of threading issues.
googletest has three features intended to raise awareness of threading issues.
1. A warning is emitted if multiple threads are running when a death test is encountered.
1. A warning is emitted if multiple threads are running when a death test is
1. Test cases with a name ending in "DeathTest" are run before all other tests.
encountered.
1. It uses `clone()` instead of `fork()` to spawn the child process on Linux (`clone()` is not available on Cygwin and Mac), as `fork()` is more likely to cause the child to hang when the parent process has multiple threads.
2. Test cases with a name ending in "DeathTest" are run before all other tests.
3. It uses `clone()` instead of `fork()` to spawn the child process on Linux
(`clone()` is not available on Cygwin and Mac), as `fork()` is more likely
to cause the child to hang when the parent process has multiple threads.
It's perfectly fine to create threads inside a death test statement; they are
It's perfectly fine to create threads inside a death test statement; they are
executed in a separate process and cannot affect the parent.
executed in a separate process and cannot affect the parent.
## Death Test Styles ##
### Death Test Styles
The "threadsafe" death test style was introduced in order to help mitigate the
The "threadsafe" death test style was introduced in order to help mitigate the
risks of testing in a possibly multithreaded environment. It trades increased
risks of testing in a possibly multithreaded environment. It trades increased
test execution time (potentially dramatically so) for improved thread safety.
test execution time (potentially dramatically so) for improved thread safety.
We suggest using the faster, default "fast" style unless your test has specific
problems with it.
You can choose a particular style of death tests by setting the flag
The automated testing framework does not set the style flag. You can choose a
programmatically:
particular style of death tests by setting the flag programmatically:
where `message` can be anything streamable to `std::ostream`. `SCOPED_TRACE`
where `message` can be anything streamable to `std::ostream`. `SCOPED_TRACE`
macro will cause the current file name, line number, and the given message to be
macro will cause the current file name, line number, and the given message to be
...
@@ -801,7 +970,7 @@ will be undone when the control leaves the current lexical scope.
...
@@ -801,7 +970,7 @@ will be undone when the control leaves the current lexical scope.
For example,
For example,
```
```c++
10:voidSub1(intn){
10:voidSub1(intn){
11:EXPECT_EQ(1,Bar(n));
11:EXPECT_EQ(1,Bar(n));
12:EXPECT_EQ(2,Bar(n+1));
12:EXPECT_EQ(2,Bar(n+1));
...
@@ -820,7 +989,7 @@ For example,
...
@@ -820,7 +989,7 @@ For example,
could result in messages like these:
could result in messages like these:
```
```none
path/to/foo_test.cc:11: Failure
path/to/foo_test.cc:11: Failure
Value of: Bar(n)
Value of: Bar(n)
Expected: 1
Expected: 1
...
@@ -834,45 +1003,56 @@ Expected: 2
...
@@ -834,45 +1003,56 @@ Expected: 2
Actual: 3
Actual: 3
```
```
Without the trace, it would've been difficult to know which invocation
Without the trace, it would've been difficult to know which invocation of
of `Sub1()` the two failures come from respectively. (You could add an
`Sub1()` the two failures come from respectively. (You could add
extra message to each assertion in `Sub1()` to indicate the value of
`n`, but that's tedious.)
an extra message to each assertion in `Sub1()` to indicate the value of `n`, but
that's tedious.)
Some tips on using `SCOPED_TRACE`:
Some tips on using `SCOPED_TRACE`:
1. With a suitable message, it's often enough to use `SCOPED_TRACE` at the beginning of a sub-routine, instead of at each call site.
1. With a suitable message, it's often enough to use `SCOPED_TRACE` at the
1. When calling sub-routines inside a loop, make the loop iterator part of the message in `SCOPED_TRACE` such that you can know which iteration the failure is from.
beginning of a sub-routine, instead of at each call site.
1. Sometimes the line number of the trace point is enough for identifying the particular invocation of a sub-routine. In this case, you don't have to choose a unique message for `SCOPED_TRACE`. You can simply use `""`.
2. When calling sub-routines inside a loop, make the loop iterator part of the
1. You can use `SCOPED_TRACE` in an inner scope when there is one in the outer scope. In this case, all active trace points will be included in the failure messages, in reverse order they are encountered.
message in `SCOPED_TRACE` such that you can know which iteration the failure
1. The trace dump is clickable in Emacs' compilation buffer - hit return on a line number and you'll be taken to that line in the source file!
is from.
3. Sometimes the line number of the trace point is enough for identifying the
particular invocation of a sub-routine. In this case, you don't have to
choose a unique message for `SCOPED_TRACE`. You can simply use `""`.
4. You can use `SCOPED_TRACE` in an inner scope when there is one in the outer
scope. In this case, all active trace points will be included in the failure
messages, in reverse order they are encountered.
5. The trace dump is clickable in Emacs - hit `return` on a line number and
you'll be taken to that line in the source file!
_Availability:_ Linux, Windows, Mac.
**Availability**: Linux, Windows, Mac.
## Propagating Fatal Failures ##
### Propagating Fatal Failures
A common pitfall when using `ASSERT_*` and `FAIL*` is not understanding that
A common pitfall when using `ASSERT_*` and `FAIL*` is not understanding that
when they fail they only abort the _current function_, not the entire test. For
when they fail they only abort the _current function_, not the entire test. For
example, the following test will segfault:
example, the following test will segfault:
```
```c++
voidSubroutine(){
voidSubroutine(){
// Generates a fatal failure and aborts the current function.
// Generates a fatal failure and aborts the current function.
ASSERT_EQ(1,2);
ASSERT_EQ(1,2);
// The following won't be executed.
// The following won't be executed.
...
...
}
}
TEST(FooTest,Bar){
TEST(FooTest,Bar){
Subroutine();
Subroutine();// The intended behavior is for the fatal failure
// The intended behavior is for the fatal failure
// in Subroutine() to abort the entire test.
// in Subroutine() to abort the entire test.
// The actual behavior: the function goes on after Subroutine() returns.
// The actual behavior: the function goes on after Subroutine() returns.
int*p=NULL;
int*p=NULL;
*p = 3; // Segfault!
*p=3;// Segfault!
}
}
```
```
To alleviate this, gUnit provides three different solutions. You could use
To alleviate this, googletest provides three different solutions. You could use
either exceptions, the `(ASSERT|EXPECT)_NO_FATAL_FAILURE` assertions or the
either exceptions, the `(ASSERT|EXPECT)_NO_FATAL_FAILURE` assertions or the
`HasFatalFailure()` function. They are described in the following two
`HasFatalFailure()` function. They are described in the following two
subsections.
subsections.
...
@@ -899,26 +1079,26 @@ int main(int argc, char** argv) {
...
@@ -899,26 +1079,26 @@ int main(int argc, char** argv) {
This listener should be added after other listeners if you have any, otherwise
This listener should be added after other listeners if you have any, otherwise
they won't see failed `OnTestPartResult`.
they won't see failed `OnTestPartResult`.
### Asserting on Subroutines ###
#### Asserting on Subroutines
As shown above, if your test calls a subroutine that has an `ASSERT_*`
As shown above, if your test calls a subroutine that has an `ASSERT_*` failure
failure in it, the test will continue after the subroutine
in it, the test will continue after the subroutine returns. This may not be what
returns. This may not be what you want.
you want.
Often people want fatal failures to propagate like exceptions. For
Often people want fatal failures to propagate like exceptions. For that
| `ASSERT_NO_FATAL_FAILURE(`_statement_`);` | `EXPECT_NO_FATAL_FAILURE(`_statement_`);` | _statement_ doesn't generate any new fatal failures in the current thread. |
`ASSERT_NO_FATAL_FAILURE(statement);` | `EXPECT_NO_FATAL_FAILURE(statement);` | `statement` doesn't generate any new fatal failures in the current thread.
Only failures in the thread that executes the assertion are checked to
Only failures in the thread that executes the assertion are checked to determine
determine the result of this type of assertions. If _statement_
the result of this type of assertions. If `statement` creates new threads,
creates new threads, failures in these threads are ignored.
failures in these threads are ignored.
Examples:
Examples:
```
```c++
ASSERT_NO_FATAL_FAILURE(Foo());
ASSERT_NO_FATAL_FAILURE(Foo());
inti;
inti;
...
@@ -927,17 +1107,16 @@ EXPECT_NO_FATAL_FAILURE({
...
@@ -927,17 +1107,16 @@ EXPECT_NO_FATAL_FAILURE({
});
});
```
```
_Availability:_ Linux, Windows, Mac. Assertions from multiple threads
**Availability**: Linux, Windows, Mac. Assertions from multiple threads are
are currently not supported.
currently not supported on Windows.
### Checking for Failures in the Current Test ###
#### Checking for Failures in the Current Test
`HasFatalFailure()` in the `::testing::Test` class returns `true` if an
`HasFatalFailure()` in the `::testing::Test` class returns `true` if an
assertion in the current test has suffered a fatal failure. This
assertion in the current test has suffered a fatal failure. This allows
allows functions to catch fatal failures in a sub-routine and return
functions to catch fatal failures in a sub-routine and return early.
early.
```
```c++
classTest{
classTest{
public:
public:
...
...
...
@@ -945,15 +1124,15 @@ class Test {
...
@@ -945,15 +1124,15 @@ class Test {
};
};
```
```
The typical usage, which basically simulates the behavior of a thrown
The typical usage, which basically simulates the behavior of a thrown exception,
exception, is:
is:
```
```c++
TEST(FooTest,Bar){
TEST(FooTest,Bar){
Subroutine();
Subroutine();
// Aborts if Subroutine() had a fatal failure.
// Aborts if Subroutine() had a fatal failure.
if (HasFatalFailure())
if(HasFatalFailure())return;
return;
// The following won't be executed.
// The following won't be executed.
...
...
}
}
...
@@ -962,25 +1141,24 @@ TEST(FooTest, Bar) {
...
@@ -962,25 +1141,24 @@ TEST(FooTest, Bar) {
If `HasFatalFailure()` is used outside of `TEST()` , `TEST_F()` , or a test
If `HasFatalFailure()` is used outside of `TEST()` , `TEST_F()` , or a test
fixture, you must add the `::testing::Test::` prefix, as in:
fixture, you must add the `::testing::Test::` prefix, as in:
```
```c++
if (::testing::Test::HasFatalFailure())
if(::testing::Test::HasFatalFailure())return;
return;
```
```
Similarly, `HasNonfatalFailure()` returns `true` if the current test
Similarly, `HasNonfatalFailure()` returns `true` if the current test has at
has at least one non-fatal failure, and `HasFailure()` returns `true`
least one non-fatal failure, and `HasFailure()` returns `true` if the current
if the current test has at least one failure of either kind.
test has at least one failure of either kind.
_Availability:_ Linux, Windows, Mac. `HasNonfatalFailure()` and
**Availability**: Linux, Windows, Mac.
`HasFailure()` are available since version 1.4.0.
# Logging Additional Information #
## Logging Additional Information
In your test code, you can call `RecordProperty("key", value)` to log
In your test code, you can call `RecordProperty("key", value)` to log additional
additional information, where `value` can be either a string or an `int`. The _last_ value recorded for a key will be emitted to the XML output
information, where `value` can be either a string or an `int`. The *last* value
if you specify one. For example, the test
recorded for a key will be emitted to the [XML output](#XmlReport) if you
*`RecordProperty()` is a static member of the `Test` class. Therefore it needs to be prefixed with `::testing::Test::` if used outside of the `TEST` body and the test fixture class.
*`key` must be a valid XML attribute name, and cannot conflict with the ones already used by Google Test (`name`, `status`, `time`, `classname`, `type_param`, and `value_param`).
* Calling `RecordProperty()` outside of the lifespan of a test is allowed. If it's called outside of a test but between a test case's `SetUpTestCase()` and `TearDownTestCase()` methods, it will be attributed to the XML element for the test case. If it's called outside of all test cases (e.g. in a test environment), it will be attributed to the top-level XML element.
_Availability_: Linux, Windows, Mac.
# Sharing Resources Between Tests in the Same Test Case #
> NOTE:
>
> * `RecordProperty()` is a static member of the `Test` class. Therefore it
> needs to be prefixed with `::testing::Test::` if used outside of the
> `TEST` body and the test fixture class.
> * `*key*` must be a valid XML attribute name, and cannot conflict with the
> ones already used by googletest (`name`, `status`, `time`, `classname`,
> `type_param`, and `value_param`).
> * Calling `RecordProperty()` outside of the lifespan of a test is allowed.
> If it's called outside of a test but between a test case's
> `SetUpTestCase()` and `TearDownTestCase()` methods, it will be attributed
> to the XML element for the test case. If it's called outside of all test
> cases (e.g. in a test environment), it will be attributed to the top-level
> XML element.
**Availability**: Linux, Windows, Mac.
## Sharing Resources Between Tests in the Same Test Case
Google Test creates a new test fixture object for each test in order to make
googletest creates a new test fixture object for each test in order to make
tests independent and easier to debug. However, sometimes tests use resources
tests independent and easier to debug. However, sometimes tests use resources
that are expensive to set up, making the one-copy-per-test model prohibitively
that are expensive to set up, making the one-copy-per-test model prohibitively
expensive.
expensive.
If the tests don't change the resource, there's no harm in them sharing a
If the tests don't change the resource, there's no harm in their sharing a
single resource copy. So, in addition to per-test set-up/tear-down, Google Test
single resource copy. So, in addition to per-test set-up/tear-down, googletest
also supports per-test-case set-up/tear-down. To use it:
also supports per-test-case set-up/tear-down. To use it:
1. In your test fixture class (say `FooTest` ), define as `static` some member variables to hold the shared resources.
1. In your test fixture class (say `FooTest` ), declare as `static` some member
1. In the same test fixture class, define a `static void SetUpTestCase()` function (remember not to spell it as **`SetupTestCase`** with a small `u`!) to set up the shared resources and a `static void TearDownTestCase()` function to tear them down.
variables to hold the shared resources.
1. Outside your test fixture class (typically just below it), define those
That's it! Google Test automatically calls `SetUpTestCase()` before running the
member variables, optionally giving them initial values.
_first test_ in the `FooTest` test case (i.e. before creating the first
1. In the same test fixture class, define a `static void SetUpTestCase()`
`FooTest` object), and calls `TearDownTestCase()` after running the _last test_
function (remember not to spell it as **`SetupTestCase`** with a small `u`!)
in it (i.e. after deleting the last `FooTest` object). In between, the tests
to set up the shared resources and a `static void TearDownTestCase()`
can use the shared resources.
function to tear them down.
That's it! googletest automatically calls `SetUpTestCase()` before running the
*first test* in the `FooTest` test case (i.e. before creating the first
`FooTest` object), and calls `TearDownTestCase()` after running the *last test*
in it (i.e. after deleting the last `FooTest` object). In between, the tests can
use the shared resources.
Remember that the test order is undefined, so your code can't depend on a test
Remember that the test order is undefined, so your code can't depend on a test
preceding or following another. Also, the tests must either not modify the
preceding or following another. Also, the tests must either not modify the state
state of any shared resource, or, if they do modify the state, they must
of any shared resource, or, if they do modify the state, they must restore the
restore the state to its original value before passing control to the next
state to its original value before passing control to the next test.
test.
Here's an example of per-test-case set-up and tear-down:
Here's an example of per-test-case set-up and tear-down:
```
```c++
classFooTest:public::testing::Test{
classFooTest:public::testing::Test{
protected:
protected:
// Per-test-case set-up.
// Per-test-case set-up.
...
@@ -1051,8 +1241,10 @@ class FooTest : public ::testing::Test {
...
@@ -1051,8 +1241,10 @@ class FooTest : public ::testing::Test {
shared_resource_=NULL;
shared_resource_=NULL;
}
}
// You can define per-test set-up and tear-down logic as usual.
// You can define per-test set-up logic as usual.
virtualvoidSetUp(){...}
virtualvoidSetUp(){...}
// You can define per-test tear-down logic as usual.
virtualvoidTearDown(){...}
virtualvoidTearDown(){...}
// Some expensive resource shared by all tests.
// Some expensive resource shared by all tests.
...
@@ -1062,16 +1254,21 @@ class FooTest : public ::testing::Test {
...
@@ -1062,16 +1254,21 @@ class FooTest : public ::testing::Test {
T*FooTest::shared_resource_=NULL;
T*FooTest::shared_resource_=NULL;
TEST_F(FooTest,Test1){
TEST_F(FooTest,Test1){
... you can refer to shared_resource here ...
...youcanrefertoshared_resource_here...
}
}
TEST_F(FooTest,Test2){
TEST_F(FooTest,Test2){
... you can refer to shared_resource here ...
...youcanrefertoshared_resource_here...
}
}
```
```
_Availability:_ Linux, Windows, Mac.
NOTE: Though the above code declares `SetUpTestCase()` protected, it may
sometimes be necessary to declare it public, such as when using it with
`TEST_P`.
**Availability**: Linux, Windows, Mac.
# Global Set-Up and Tear-Down #
## Global Set-Up and Tear-Down
Just as you can do set-up and tear-down at the test level and the test case
Just as you can do set-up and tear-down at the test level and the test case
level, you can also do it at the test program level. Here's how.
level, you can also do it at the test program level. Here's how.
...
@@ -1079,21 +1276,23 @@ level, you can also do it at the test program level. Here's how.
...
@@ -1079,21 +1276,23 @@ level, you can also do it at the test program level. Here's how.
First, you subclass the `::testing::Environment` class to define a test
First, you subclass the `::testing::Environment` class to define a test
environment, which knows how to set-up and tear-down:
environment, which knows how to set-up and tear-down:
```
```c++
classEnvironment{
classEnvironment{
public:
public:
virtual~Environment(){}
virtual~Environment(){}
// Override this to define how to set up the environment.
// Override this to define how to set up the environment.
virtualvoidSetUp(){}
virtualvoidSetUp(){}
// Override this to define how to tear down the environment.
// Override this to define how to tear down the environment.
virtualvoidTearDown(){}
virtualvoidTearDown(){}
};
};
```
```
Then, you register an instance of your environment class with Google Test by
Then, you register an instance of your environment class with googletest by
calling the `::testing::AddGlobalTestEnvironment()` function:
calling the `::testing::AddGlobalTestEnvironment()` function:
However, we strongly recommend you to write your own `main()` and call
However, we strongly recommend you to write your own `main()` and call
`AddGlobalTestEnvironment()` there, as relying on initialization of global
`AddGlobalTestEnvironment()` there, as relying on initialization of global
variables makes the code harder to read and may cause problems when you
variables makes the code harder to read and may cause problems when you register
register multiple environments from different translation units and the
multiple environments from different translation units and the environments have
environments have dependencies among them (remember that the compiler doesn't
dependencies among them (remember that the compiler doesn't guarantee the order
guarantee the order in which global variables from different translation units
in which global variables from different translation units are initialized).
are initialized).
## Value-Parameterized Tests
_Availability:_ Linux, Windows, Mac.
*Value-parameterized tests* allow you to test your code with different
parameters without writing multiple copies of the same test. This is useful in a
number of situations, for example:
* You have a piece of code whose behavior is affected by one or more
command-line flags. You want to make sure your code performs correctly for
various values of those flags.
* You want to test different implementations of an OO interface.
* You want to test your code over various inputs (a.k.a. data-driven testing).
This feature is easy to abuse, so please exercise your good sense when doing
it!
### How to Write Value-Parameterized Tests
To write value-parameterized tests, first you should define a fixture class. It
must be derived from both `::testing::Test` and
`::testing::WithParamInterface<T>` (the latter is a pure interface), where `T`
is the type of your parameter values. For convenience, you can just derive the
fixture class from `::testing::TestWithParam<T>`, which itself is derived from
both `::testing::Test` and `::testing::WithParamInterface<T>`. `T` can be any
copyable type. If it's a raw pointer, you are responsible for managing the
lifespan of the pointed values.
NOTE: If your test fixture defines `SetUpTestCase()` or `TearDownTestCase()`
they must be declared **public** rather than **protected** in order to use
`TEST_P`.
```c++
# Value Parameterized Tests #
classFooTest:
public::testing::TestWithParam<constchar*>{
_Value-parameterized tests_ allow you to test your code with different
parameters without writing multiple copies of the same test.
Suppose you write a test for your code and then realize that your code is affected by a presence of a Boolean command line flag.
```
TEST(MyCodeTest, TestFoo) {
// A code to test foo().
}
```
Usually people factor their test code into a function with a Boolean parameter in such situations. The function sets the flag, then executes the testing code.
```
void TestFooHelper(bool flag_value) {
flag = flag_value;
// A code to test foo().
}
TEST(MyCodeTest, TestFoo) {
TestFooHelper(false);
TestFooHelper(true);
}
```
But this setup has serious drawbacks. First, when a test assertion fails in your tests, it becomes unclear what value of the parameter caused it to fail. You can stream a clarifying message into your `EXPECT`/`ASSERT` statements, but it you'll have to do it with all of them. Second, you have to add one such helper function per test. What if you have ten tests? Twenty? A hundred?
Value-parameterized tests will let you write your test only once and then easily instantiate and run it with an arbitrary number of parameter values.
Here are some other situations when value-parameterized tests come handy:
* You want to test different implementations of an OO interface.
* You want to test your code over various inputs (a.k.a. data-driven testing). This feature is easy to abuse, so please exercise your good sense when doing it!
## How to Write Value-Parameterized Tests ##
To write value-parameterized tests, first you should define a fixture
class. It must be derived from both `::testing::Test` and
`::testing::WithParamInterface<T>` (the latter is a pure interface),
where `T` is the type of your parameter values. For convenience, you
can just derive the fixture class from `::testing::TestWithParam<T>`,
which itself is derived from both `::testing::Test` and
`::testing::WithParamInterface<T>`. `T` can be any copyable type. If
it's a raw pointer, you are responsible for managing the lifespan of
the pointed values.
```
class FooTest : public ::testing::TestWithParam<const char*> {
// You can implement all the usual fixture class members here.
// You can implement all the usual fixture class members here.
// To access the test parameter, call GetParam() from class
// To access the test parameter, call GetParam() from class
// TestWithParam<T>.
// TestWithParam<T>.
...
@@ -1193,11 +1371,11 @@ class BarTest : public BaseTest,
...
@@ -1193,11 +1371,11 @@ class BarTest : public BaseTest,
};
};
```
```
Then, use the `TEST_P` macro to define as many test patterns using
Then, use the `TEST_P` macro to define as many test patterns using this fixture
this fixture as you want. The `_P` suffix is for "parameterized" or
as you want. The `_P` suffix is for "parameterized" or "pattern", whichever you
"pattern", whichever you prefer to think.
prefer to think.
```
```c++
TEST_P(FooTest,DoesBlah){
TEST_P(FooTest,DoesBlah){
// Inside a test, access the test parameter with the GetParam() method
// Inside a test, access the test parameter with the GetParam() method
| `ValuesIn(container)` and `ValuesIn(begin, end)` | Yields values from a C-style array, an STL-style container, or an iterator range `[begin, end)`. `container`, `begin`, and `end` can be expressions whose values are determined at run time. |
: : begin+step+step, ...}`. The values do not :
| `Bool()` | Yields sequence `{false, true}`. |
: : include `end`. `step` defaults to 1. :
| `Combine(g1, g2, ..., gN)` | Yields all combinations (the Cartesian product for the math savvy) of the values generated by the `N` generators. This is only available if your system provides the `<tr1/tuple>` header. If you are sure your system does, and Google Test disagrees, you can override it by defining `GTEST_HAS_TR1_TUPLE=1`. See comments in [include/gtest/internal/gtest-port.h](../include/gtest/internal/gtest-port.h) for more information. |
The tests from the instantiation above will have these names:
The tests from the instantiation above will have these names:
*`AnotherInstantiationName/FooTest.DoesBlah/0` for `"cat"`
*`AnotherInstantiationName/FooTest.DoesBlah/0` for `"cat"`
*`AnotherInstantiationName/FooTest.DoesBlah/1` for `"dog"`
*`AnotherInstantiationName/FooTest.DoesBlah/1` for `"dog"`
*`AnotherInstantiationName/FooTest.HasBlahBlah/0` for `"cat"`
*`AnotherInstantiationName/FooTest.HasBlahBlah/0` for `"cat"`
*`AnotherInstantiationName/FooTest.HasBlahBlah/1` for `"dog"`
*`AnotherInstantiationName/FooTest.HasBlahBlah/1` for `"dog"`
Please note that `INSTANTIATE_TEST_CASE_P` will instantiate _all_
Please note that `INSTANTIATE_TEST_CASE_P` will instantiate *all* tests in the
tests in the given test case, whether their definitions come before or
given test case, whether their definitions come before or*after* the
_after_ the `INSTANTIATE_TEST_CASE_P` statement.
`INSTANTIATE_TEST_CASE_P` statement.
You can see
You can see sample7_unittest.cc and sample8_unittest.cc for more examples.
[these](../samples/sample7_unittest.cc)
[files](../samples/sample8_unittest.cc) for more examples.
_Availability_: Linux, Windows (requires MSVC 8.0 or above), Mac; since version 1.2.0.
**Availability**: Linux, Windows (requires MSVC 8.0 or above), Mac
## Creating Value-Parameterized Abstract Tests ##
### Creating Value-Parameterized Abstract Tests
In the above, we define and instantiate `FooTest` in the same source
In the above, we define and instantiate `FooTest` in the *same* source file.
file. Sometimes you may want to define value-parameterized tests in a
Sometimes you may want to define value-parameterized tests in a library and let
library and let other people instantiate them later. This pattern is
other people instantiate them later. This pattern is known as *abstract tests*.
known as <i>abstract tests</i>. As an example of its application, when you
As an example of its application, when you are designing an interface you can
are designing an interface you can write a standard suite of abstract
write a standard suite of abstract tests (perhaps using a factory function as
tests (perhaps using a factory function as the test parameter) that
the test parameter) that all implementations of the interface are expected to
all implementations of the interface are expected to pass. When
pass. When someone implements the interface, they can instantiate your suite to
someone implements the interface, they can instantiate your suite to get
get all the interface-conformance tests for free.
all the interface-conformance tests for free.
To define abstract tests, you should organize your code like this:
To define abstract tests, you should organize your code like this:
1. Put the definition of the parameterized test fixture class (e.g. `FooTest`) in a header file, say `foo_param_test.h`. Think of this as _declaring_ your abstract tests.
1. Put the definition of the parameterized test fixture class (e.g. `FooTest`)
1. Put the `TEST_P` definitions in `foo_param_test.cc`, which includes `foo_param_test.h`. Think of this as _implementing_ your abstract tests.
in a header file, say `foo_param_test.h`. Think of this as *declaring* your
abstract tests.
1. Put the `TEST_P` definitions in `foo_param_test.cc`, which includes
`foo_param_test.h`. Think of this as *implementing* your abstract tests.
Once they are defined, you can instantiate them by including `foo_param_test.h`,
invoking `INSTANTIATE_TEST_CASE_P()`, and depending on the library target that
contains `foo_param_test.cc`. You can instantiate the same abstract test case
multiple times, possibly in different source files.
Once they are defined, you can instantiate them by including
### Specifying Names for Value-Parameterized Test Parameters
`foo_param_test.h`, invoking `INSTANTIATE_TEST_CASE_P()`, and linking
with `foo_param_test.cc`. You can instantiate the same abstract test
case multiple times, possibly in different source files.
# Typed Tests #
The optional last argument to `INSTANTIATE_TEST_CASE_P()` allows the user to
specify a function or functor that generates custom test name suffixes based on
the test parameters. The function should accept one argument of type
`testing::TestParamInfo<class ParamType>`, and return `std::string`.
Suppose you have multiple implementations of the same interface and
`testing::PrintToStringParamName` is a builtin test suffix generator that
want to make sure that all of them satisfy some common requirements.
returns the value of `testing::PrintToString(GetParam())`. It does not work for
Or, you may have defined several types that are supposed to conform to
`std::string` or C strings.
the same "concept" and you want to verify it. In both cases, you want
the same test logic repeated for different types.
While you can write one `TEST` or `TEST_F` for each type you want to
NOTE: test names must be non-empty, unique, and may only contain ASCII
test (and you may even factor the test logic into a function template
alphanumeric characters. In particular, they [should not contain
that you invoke from the `TEST`), it's tedious and doesn't scale:
| `$ foo_test --gtest_repeat=-1` | A negative count means repeating forever. |
Repeat foo_test 1000 times and don't stop at failures.
| `$ foo_test --gtest_repeat=1000 --gtest_break_on_failure` | Repeat foo\_test 1000 times, stopping at the first failure. This is especially useful when running under a debugger: when the testfails, it will drop into the debugger and you can then inspect variables and stacks. |
| `$ foo_test --gtest_repeat=1000 --gtest_filter=FooBar` | Repeat the tests whose name matches the filter 1000 times. |
If your test program contains global set-up/tear-down code registered
$ foo_test --gtest_repeat=-1
using `AddGlobalTestEnvironment()`, it will be repeated in each
A negative count means repeating forever.
iteration as well, as the flakiness may be in it. You can also specify
the repeat count by setting the `GTEST_REPEAT` environment variable.
@@ -2053,18 +2287,26 @@ could generate this report:
...
@@ -2053,18 +2287,26 @@ could generate this report:
Things to note:
Things to note:
* The `tests` attribute of a `<testsuites>` or `<testsuite>` element tells how many test functions the Google Test program or test case contains, while the `failures` attribute tells how many of them failed.
* The `tests` attribute of a `<testsuites>` or `<testsuite>` element tells how
* The `time` attribute expresses the duration of the test, test case, or entire test program in milliseconds.
many test functions the googletest program or test case contains, while the
* Each `<failure>` element corresponds to a single failed Google Test assertion.
`failures` attribute tells how many of them failed.
* Some JUnit concepts don't apply to Google Test, yet we have to conform to the DTD. Therefore you'll see some dummy elements and attributes in the report. You can safely ignore these parts.
* The `time` attribute expresses the duration of the test, test case, or
entire test program in seconds.
* The `timestamp` attribute records the local date and time of the test
execution.
_Availability:_ Linux, Windows, Mac.
* Each `<failure>` element corresponds to a single failed googletest
assertion.
#### Generating an JSON Report {#JsonReport}
**Availability**: Linux, Windows, Mac.
#### Generating an JSON Report
gUnit can also emit a JSON report as an alternative format to XML. To generate
googletest can also emit a JSON report as an alternative format to XML. To
the JSON report, set the `GUNIT_OUTPUT` environment variable or the
generate the JSON report, set the `GTEST_OUTPUT` environment variable or the
`--gunit_output` flag to the string `"json:path_to_output_file"`, which will
`--gtest_output` flag to the string `"json:path_to_output_file"`, which will
create the file at the given location. You can also just use the string
create the file at the given location. You can also just use the string
`"json"`, in which case the output can be found in the `test_detail.json` file
`"json"`, in which case the output can be found in the `test_detail.json` file
in the current directory.
in the current directory.
...
@@ -2139,8 +2381,8 @@ The report format conforms to the following JSON Schema:
...
@@ -2139,8 +2381,8 @@ The report format conforms to the following JSON Schema:
}
}
```
```
The report uses the format that conforms to the following Proto3 using the
The report uses the format that conforms to the following Proto3 using the[JSON
@@ -2261,156 +2503,34 @@ IMPORTANT: The exact format of the JSON document is subject to change.
...
@@ -2261,156 +2503,34 @@ IMPORTANT: The exact format of the JSON document is subject to change.
**Availability**: Linux, Windows, Mac.
**Availability**: Linux, Windows, Mac.
## Controlling How Failures Are Reported ##
### Controlling How Failures Are Reported
### Turning Assertion Failures into Break-Points ###
#### Turning Assertion Failures into Break-Points
When running test programs under a debugger, it's very convenient if the
When running test programs under a debugger, it's very convenient if the
debugger can catch an assertion failure and automatically drop into interactive
debugger can catch an assertion failure and automatically drop into interactive
mode. Google Test's _break-on-failure_ mode supports this behavior.
mode. googletest's *break-on-failure* mode supports this behavior.
To enable it, set the `GTEST_BREAK_ON_FAILURE` environment variable to a value
To enable it, set the `GTEST_BREAK_ON_FAILURE` environment variable to a value
other than `0` . Alternatively, you can use the `--gtest_break_on_failure`
other than `0` . Alternatively, you can use the `--gtest_break_on_failure`
command line flag.
command line flag.
_Availability:_ Linux, Windows, Mac.
### Disabling Catching Test-Thrown Exceptions ###
Google Test can be used either with or without exceptions enabled. If
a test throws a C++ exception or (on Windows) a structured exception
(SEH), by default Google Test catches it, reports it as a test
failure, and continues with the next test method. This maximizes the
coverage of a test run. Also, on Windows an uncaught exception will
cause a pop-up window, so catching the exceptions allows you to run
the tests automatically.
When debugging the test failures, however, you may instead want the
exceptions to be handled by the debugger, such that you can examine
the call stack when an exception is thrown. To achieve that, set the
`GTEST_CATCH_EXCEPTIONS` environment variable to `0`, or use the
`--gtest_catch_exceptions=0` flag when running the tests.
**Availability**: Linux, Windows, Mac.
**Availability**: Linux, Windows, Mac.
### Letting Another Testing Framework Drive ###
#### Disabling Catching Test-Thrown Exceptions
If you work on a project that has already been using another testing
framework and is not ready to completely switch to Google Test yet,
you can get much of Google Test's benefit by using its assertions in
your existing tests. Just change your `main()` function to look
like:
```
#include "gtest/gtest.h"
int main(int argc, char** argv) {
::testing::GTEST_FLAG(throw_on_failure) = true;
// Important: Google Test must be initialized.
::testing::InitGoogleTest(&argc, argv);
... whatever your existing testing framework requires ...
}
```
With that, you can use Google Test assertions in addition to the
native assertions your testing framework provides, for example:
```
void TestFooDoesBar() {
Foo foo;
EXPECT_LE(foo.Bar(1), 100); // A Google Test assertion.
CPPUNIT_ASSERT(foo.IsEmpty()); // A native assertion.
}
```
If a Google Test assertion fails, it will print an error message and
throw an exception, which will be treated as a failure by your host
testing framework. If you compile your code with exceptions disabled,
a failed Google Test assertion will instead exit your program with a
non-zero code, which will also signal a test failure to your test
runner.
If you don't write `::testing::GTEST_FLAG(throw_on_failure) = true;` in
your `main()`, you can alternatively enable this feature by specifying
the `--gtest_throw_on_failure` flag on the command-line or setting the
`GTEST_THROW_ON_FAILURE` environment variable to a non-zero value.
Death tests are _not_ supported when other test framework is used to organize tests.
_Availability:_ Linux, Windows, Mac; since v1.3.0.
## Distributing Test Functions to Multiple Machines ##
If you have more than one machine you can use to run a test program,
you might want to run the test functions in parallel and get the
result faster. We call this technique _sharding_, where each machine
is called a _shard_.
Google Test is compatible with test sharding. To take advantage of
this feature, your test runner (not part of Google Test) needs to do
the following:
1. Allocate a number of machines (shards) to run the tests.
googletest can be used either with or without exceptions enabled. If a test
1. On each shard, set the `GTEST_TOTAL_SHARDS` environment variable to the total number of shards. It must be the same for all shards.
throws a C++ exception or (on Windows) a structured exception (SEH), by default
1. On each shard, set the `GTEST_SHARD_INDEX` environment variable to the index of the shard. Different shards must be assigned different indices, which must be in the range `[0, GTEST_TOTAL_SHARDS - 1]`.
googletest catches it, reports it as a test failure, and continues with the next
1. Run the same test program on all shards. When Google Test sees the above two environment variables, it will select a subset of the test functions to run. Across all shards, each test function in the program will be run exactly once.
test method. This maximizes the coverage of a test run. Also, on Windows an
1. Wait for all shards to finish, then collect and report the results.
uncaught exception will cause a pop-up window, so catching the exceptions allows
you to run the tests automatically.
Your project may have tests that were written without Google Test and
When debugging the test failures, however, you may instead want the exceptions
thus don't understand this protocol. In order for your test runner to
to be handled by the debugger, such that you can examine the call stack when an
figure out which test supports sharding, it can set the environment
exception is thrown. To achieve that, set the `GTEST_CATCH_EXCEPTIONS`
variable `GTEST_SHARD_STATUS_FILE` to a non-existent file path. If a
environment variable to `0`, or use the `--gtest_catch_exceptions=0` flag when
test program supports sharding, it will create this file to
running the tests.
acknowledge the fact (the actual contents of the file are not
important at this time; although we may stick some useful information
in it in the future.); otherwise it will not create it.
Here's an example to make it clear. Suppose you have a test program
**Availability**: Linux, Windows, Mac.
`foo_test` that contains the following 5 test functions:
```
TEST(A, V)
TEST(A, W)
TEST(B, X)
TEST(B, Y)
TEST(B, Z)
```
and you have 3 machines at your disposal. To run the test functions in
parallel, you would set `GTEST_TOTAL_SHARDS` to 3 on all machines, and
set `GTEST_SHARD_INDEX` to 0, 1, and 2 on the machines respectively.
Then you would run the same `foo_test` on each machine.
Google Test reserves the right to change how the work is distributed
across the shards, but here's one possible scenario:
* Machine #0 runs `A.V` and `B.X`.
* Machine #1 runs `A.W` and `B.Y`.
* Machine #2 runs `B.Z`.
_Availability:_ Linux, Windows, Mac; since version 1.3.0.
# Fusing Google Test Source Files #
Google Test's implementation consists of ~30 files (excluding its own
tests). Sometimes you may want them to be packaged up in two files (a
`.h` and a `.cc`) instead, such that you can easily copy them to a new
machine and start hacking there. For this we provide an experimental
Python script `fuse_gtest_files.py` in the `scripts/` directory (since release 1.3.0).
Assuming you have Python 2.4 or above installed on your machine, just
go to that directory and run
```
python fuse_gtest_files.py OUTPUT_DIR
```
and you should see an `OUTPUT_DIR` directory being created with files
`gtest/gtest.h` and `gtest/gtest-all.cc` in it. These files contain
everything you need to use Google Test. Just copy them to anywhere
you want and you are ready to write tests. You can use the
[scripts/test/Makefile](../scripts/test/Makefile)
file as an example on how to compile your tests against them.
# Where to Go from Here #
Congratulations! You've now learned more advanced Google Test tools and are
ready to tackle more complex testing tasks. If you want to dive even deeper, you
can read the [Frequently-Asked Questions](faq.md).
If you cannot find the answer to your question here, and you have read
## Why should test case names and test names not contain underscore?
[Primer](primer.md) and [AdvancedGuide](advanced.md), send it to
googletestframework@googlegroups.com.
## Why should I use Google Test instead of my favorite C++ testing framework? ##
Underscore (`_`) is special, as C++ reserves the following to be used by the
compiler and the standard library:
First, let us say clearly that we don't want to get into the debate of
1. any identifier that starts with an `_` followed by an upper-case letter, and
which C++ testing framework is **the best**. There exist many fine
1. any identifier that contains two consecutive underscores (i.e. `__`)
frameworks for writing C++ tests, and we have tremendous respect for
*anywhere* in its name.
the developers and users of them. We don't think there is (or will
be) a single best framework - you have to pick the right tool for the
particular task you are tackling.
We created Google Test because we couldn't find the right combination
User code is *prohibited* from using such identifiers.
of features and conveniences in an existing framework to satisfy _our_
needs. The following is a list of things that _we_ like about Google
Test. We don't claim them to be unique to Google Test - rather, the
combination of them makes Google Test the choice for us. We hope this
list can help you decide whether it is for you too.
* Google Test is designed to be portable: it doesn't require exceptions or RTTI; it works around various bugs in various compilers and environments; etc. As a result, it works on Linux, Mac OS X, Windows and several embedded operating systems.
* Nonfatal assertions (`EXPECT_*`) have proven to be great time savers, as they allow a test to report multiple failures in a single edit-compile-test cycle.
* It's easy to write assertions that generate informative messages: you just use the stream syntax to append any additional information, e.g. `ASSERT_EQ(5, Foo(i)) << " where i = " << i;`. It doesn't require a new set of macros or special functions.
* Google Test automatically detects your tests and doesn't require you to enumerate them in order to run them.
* Death tests are pretty handy for ensuring that your asserts in production code are triggered by the right conditions.
*`SCOPED_TRACE` helps you understand the context of an assertion failure when it comes from inside a sub-routine or loop.
* You can decide which tests to run using name patterns. This saves time when you want to quickly reproduce a test failure.
* Google Test can generate XML test result reports that can be parsed by popular continuous build system like Hudson.
* Simple things are easy in Google Test, while hard things are possible: in addition to advanced features like [global test environments](advanced.md#global-set-up-and-tear-down) and tests parameterized by [values](advanced.md#value-parameterized-tests) or [types](docs/advanced.md#typed-tests), Google Test supports various ways for the user to extend the framework -- if Google Test doesn't do something out of the box, chances are that a user can implement the feature using Google Test's public API, without changing Google Test itself. In particular, you can:
* expand your testing vocabulary by defining [custom predicates](advanced.md#predicate-assertions-for-better-error-messages),
* teach Google Test how to [print your types](advanced.md#teaching-google-test-how-to-print-your-values),
* define your own testing macros or utilities and verify them using Google Test's [Service Provider Interface](advanced.md#catching-failures), and
* reflect on the test cases or change the test output format by intercepting the [test events](advanced.md#extending-google-test-by-handling-test-events).
## I'm getting warnings when compiling Google Test. Would you fix them? ##
We strive to minimize compiler warnings Google Test generates. Before releasing a new version, we test to make sure that it doesn't generate warnings when compiled using its CMake script on Windows, Linux, and Mac OS.
Unfortunately, this doesn't mean you are guaranteed to see no warnings when compiling Google Test in your environment:
* You may be using a different compiler as we use, or a different version of the same compiler. We cannot possibly test for all compilers.
* You may be compiling on a different platform as we do.
* Your project may be using different compiler flags as we do.
It is not always possible to make Google Test warning-free for everyone. Or, it may not be desirable if the warning is rarely enabled and fixing the violations makes the code more complex.
If you see warnings when compiling Google Test, we suggest that you use the `-isystem` flag (assuming your are using GCC) to mark Google Test headers as system headers. That'll suppress warnings from Google Test headers.
## Why should not test case names and test names contain underscore? ##
Underscore (`_`) is special, as C++ reserves the following to be used by
the compiler and the standard library:
1. any identifier that starts with an `_` followed by an upper-case letter, and
1. any identifier that contains two consecutive underscores (i.e. `__`) _anywhere_ in its name.
User code is _prohibited_ from using such identifiers.
Now let's look at what this means for `TEST` and `TEST_F`.
Now let's look at what this means for `TEST` and `TEST_F`.
Currently `TEST(TestCaseName, TestName)` generates a class named
Currently `TEST(TestCaseName, TestName)` generates a class named
`TestCaseName_TestName_Test`. What happens if `TestCaseName` or `TestName`
`TestCaseName_TestName_Test`. What happens if `TestCaseName` or `TestName`
contains `_`?
contains `_`?
1. If `TestCaseName` starts with an `_` followed by an upper-case letter (say, `_Foo`), we end up with `_Foo_TestName_Test`, which is reserved and thus invalid.
1. If `TestCaseName` starts with an `_` followed by an upper-case letter (say,
1. If `TestCaseName` ends with an `_` (say, `Foo_`), we get `Foo__TestName_Test`, which is invalid.
`_Foo`), we end up with `_Foo_TestName_Test`, which is reserved and thus
1. If `TestName` starts with an `_` (say, `_Bar`), we get `TestCaseName__Bar_Test`, which is invalid.
invalid.
1. If `TestName` ends with an `_` (say, `Bar_`), we get `TestCaseName_Bar__Test`, which is invalid.
1. If `TestCaseName` ends with an `_` (say, `Foo_`), we get
`Foo__TestName_Test`, which is invalid.
1. If `TestName` starts with an `_` (say, `_Bar`), we get
`TestCaseName__Bar_Test`, which is invalid.
1. If `TestName` ends with an `_` (say, `Bar_`), we get
`TestCaseName_Bar__Test`, which is invalid.
So clearly `TestCaseName` and `TestName` cannot start or end with `_` (Actually,
`TestCaseName` can start with `_` -- as long as the `_` isn't followed by an
upper-case letter. But that's getting complicated. So for simplicity we just say
that it cannot start with `_`.).
So clearly `TestCaseName` and `TestName` cannot start or end with `_`
It may seem fine for `TestCaseName` and `TestName` to contain `_` in the middle.
(Actually, `TestCaseName` can start with `_` -- as long as the `_` isn't
However, consider this:
followed by an upper-case letter. But that's getting complicated. So
for simplicity we just say that it cannot start with `_`.).
It may seem fine for `TestCaseName` and `TestName` to contain `_` in the
middle. However, consider this:
```c++
```c++
TEST(Time,Flies_Like_An_Arrow){...}
TEST(Time,Flies_Like_An_Arrow){...}
TEST(Time_Flies,Like_An_Arrow){...}
TEST(Time_Flies,Like_An_Arrow){...}
```
```
Now, the two `TEST`s will both generate the same class
Now, the two `TEST`s will both generate the same class
(`Time_Files_Like_An_Arrow_Test`). That's not good.
(`Time_Flies_Like_An_Arrow_Test`). That's not good.
So for simplicity, we just ask the users to avoid `_` in `TestCaseName`
So for simplicity, we just ask the users to avoid `_` in `TestCaseName` and
and `TestName`. The rule is more constraining than necessary, but it's
`TestName`. The rule is more constraining than necessary, but it's simple and
simple and easy to remember. It also gives Google Test some wiggle
easy to remember. It also gives googletest some wiggle room in case its
room in case its implementation needs to change in the future.
implementation needs to change in the future.
If you violate the rule, there may not be immediately consequences,
If you violate the rule, there may not be immediate consequences, but your test
but your test may (just may) break with a new compiler (or a new
may (just may) break with a new compiler (or a new version of the compiler you
version of the compiler you are using) or with a new version of Google
are using) or with a new version of googletest. Therefore it's best to follow
Test. Therefore it's best to follow the rule.
the rule.
## Why is it not recommended to install a pre-compiled copy of Google Test (for example, into /usr/local)? ##
## Why does googletest support `EXPECT_EQ(NULL, ptr)` and `ASSERT_EQ(NULL, ptr)` but not `EXPECT_NE(NULL, ptr)` and `ASSERT_NE(NULL, ptr)`?
In the early days, we said that you could install
First of all you can use `EXPECT_NE(nullptr, ptr)` and `ASSERT_NE(nullptr,
compiled Google Test libraries on `*`nix systems using `make install`.
ptr)`. This is the preferred syntax in the style guide because nullptr does not
Then every user of your machine can write tests without
have the type problems that NULL does. Which is why NULL does not work.
recompiling Google Test.
Due to some peculiarity of C++, it requires some non-trivial template meta
This seemed like a good idea, but it has a
programming tricks to support using `NULL` as an argument of the `EXPECT_XX()`
got-cha: every user needs to compile their tests using the _same_ compiler
and `ASSERT_XX()` macros. Therefore we only do it where it's most needed
flags used to compile the installed Google Test libraries; otherwise
(otherwise we make the implementation of googletest harder to maintain and more
they may run into undefined behaviors (i.e. the tests can behave
error-prone than necessary).
strangely and may even crash for no obvious reasons).
The `EXPECT_EQ()` macro takes the *expected* value as its first argument and the
Why? Because C++ has this thing called the One-Definition Rule: if
*actual* value as the second. It's reasonable that someone wants to write
two C++ source files contain different definitions of the same
`EXPECT_EQ(NULL, some_expression)`, and this indeed was requested several times.
class/function/variable, and you link them together, you violate the
Therefore we implemented it.
rule. The linker may or may not catch the error (in many cases it's
not required by the C++ standard to catch the violation). If it
The need for `EXPECT_NE(NULL, ptr)` isn't nearly as strong. When the assertion
doesn't, you get strange run-time behaviors that are unexpected and
fails, you already know that `ptr` must be `NULL`, so it doesn't add any
hard to debug.
information to print `ptr` in this case. That means `EXPECT_TRUE(ptr != NULL)`
works just as well.
If you compile Google Test and your test code using different compiler
flags, they may see different definitions of the same
If we were to support `EXPECT_NE(NULL, ptr)`, for consistency we'll have to
class/function/variable (e.g. due to the use of `#if` in Google Test).
support `EXPECT_NE(ptr, NULL)` as well, as unlike `EXPECT_EQ`, we don't have a
Therefore, for your sanity, we recommend to avoid installing pre-compiled
convention on the order of the two arguments for `EXPECT_NE`. This means using
Google Test libraries. Instead, each project should compile
the template meta programming tricks twice in the implementation, making it even
Google Test itself such that it can be sure that the same flags are
harder to understand and maintain. We believe the benefit doesn't justify the
used for both Google Test and the tests.
cost.
## How do I generate 64-bit binaries on Windows (using Visual Studio 2008)? ##
Finally, with the growth of the gMock matcher library, we are encouraging people
to use the unified `EXPECT_THAT(value, matcher)` syntax more often in tests. One
(Answered by Trevor Robinson)
significant advantage of the matcher approach is that matchers can be easily
combined to form new matchers, while the `EXPECT_NE`, etc, macros cannot be
Load the supplied Visual Studio solution file, either `msvc\gtest-md.sln` or
easily combined. Therefore we want to invest more in the matchers than in the
`msvc\gtest.sln`. Go through the migration wizard to migrate the
solution and project files to Visual Studio 2008. Select
`Configuration Manager...` from the `Build` menu. Select `<New...>` from
the `Active solution platform` dropdown. Select `x64` from the new
platform dropdown, leave `Copy settings from` set to `Win32` and
`Create new project platforms` checked, then click `OK`. You now have
`Win32` and `x64` platform configurations, selectable from the
`Standard` toolbar, which allow you to toggle between building 32-bit or
64-bit binaries (or both at once using Batch Build).
In order to prevent build output files from overwriting one another,
you'll need to change the `Intermediate Directory` settings for the
newly created platform configuration across all the projects. To do
this, multi-select (e.g. using shift-click) all projects (but not the
solution) in the `Solution Explorer`. Right-click one of them and
select `Properties`. In the left pane, select `Configuration Properties`,
and from the `Configuration` dropdown, select `All Configurations`.
Make sure the selected platform is `x64`. For the
`Intermediate Directory` setting, change the value from
`$(PlatformName)\$(ConfigurationName)` to
`$(OutDir)\$(ProjectName)`. Click `OK` and then build the
solution. When the build is complete, the 64-bit binaries will be in
the `msvc\x64\Debug` directory.
## Can I use Google Test on MinGW? ##
We haven't tested this ourselves, but Per Abrahamsen reported that he
was able to compile and install Google Test successfully when using
MinGW from Cygwin. You'll need to configure it with:
Please contact `googletestframework@googlegroups.com` if you are
interested in improving the support for MinGW.
## Why does Google Test support EXPECT\_EQ(NULL, ptr) and ASSERT\_EQ(NULL, ptr) but not EXPECT\_NE(NULL, ptr) and ASSERT\_NE(NULL, ptr)? ##
Due to some peculiarity of C++, it requires some non-trivial template
meta programming tricks to support using `NULL` as an argument of the
`EXPECT_XX()` and `ASSERT_XX()` macros. Therefore we only do it where
it's most needed (otherwise we make the implementation of Google Test
harder to maintain and more error-prone than necessary).
The `EXPECT_EQ()` macro takes the _expected_ value as its first
argument and the _actual_ value as the second. It's reasonable that
someone wants to write `EXPECT_EQ(NULL, some_expression)`, and this
indeed was requested several times. Therefore we implemented it.
The need for `EXPECT_NE(NULL, ptr)` isn't nearly as strong. When the
assertion fails, you already know that `ptr` must be `NULL`, so it
doesn't add any information to print ptr in this case. That means
`EXPECT_TRUE(ptr != NULL)` works just as well.
If we were to support `EXPECT_NE(NULL, ptr)`, for consistency we'll
have to support `EXPECT_NE(ptr, NULL)` as well, as unlike `EXPECT_EQ`,
we don't have a convention on the order of the two arguments for
`EXPECT_NE`. This means using the template meta programming tricks
twice in the implementation, making it even harder to understand and
maintain. We believe the benefit doesn't justify the cost.
Finally, with the growth of Google Mock's [matcher](../../googlemock/docs/CookBook.md#using-matchers-in-google-test-assertions) library, we are
encouraging people to use the unified `EXPECT_THAT(value, matcher)`
syntax more often in tests. One significant advantage of the matcher
approach is that matchers can be easily combined to form new matchers,
while the `EXPECT_NE`, etc, macros cannot be easily
combined. Therefore we want to invest more in the matchers than in the
`EXPECT_XX()` macros.
`EXPECT_XX()` macros.
## Does Google Test support running tests in parallel? ##
## I need to test that different implementations of an interface satisfy some common requirements. Should I use typed tests or value-parameterized tests?
Test runners tend to be tightly coupled with the build/test
environment, and Google Test doesn't try to solve the problem of
running tests in parallel. Instead, we tried to make Google Test work
nicely with test runners. For example, Google Test's XML report
contains the time spent on each test, and its `gtest_list_tests` and
`gtest_filter` flags can be used for splitting the execution of test
methods into multiple processes. These functionalities can help the
test runner run the tests in parallel.
## Why don't Google Test run the tests in different threads to speed things up? ##
For testing various implementations of the same interface, either typed tests or
value-parameterized tests can get it done. It's really up to you the user to
decide which is more convenient for you, depending on your particular case. Some
rough guidelines:
It's difficult to write thread-safe code. Most tests are not written
* Typed tests can be easier to write if instances of the different
with thread-safety in mind, and thus may not work correctly in a
implementations can be created the same way, modulo the type. For example,
multi-threaded setting.
if all these implementations have a public default constructor (such that
you can write `new TypeParam`), or if their factory functions have the same
form (e.g. `CreateInstance<TypeParam>()`).
* Value-parameterized tests can be easier to write if you need different code
patterns to create different implementations' instances, e.g. `new Foo` vs
`new Bar(5)`. To accommodate for the differences, you can write factory
function wrappers and pass these function pointers to the tests as their
parameters.
* When a typed test fails, the output includes the name of the type, which can
help you quickly identify which implementation is wrong. Value-parameterized
tests cannot do this, so there you'll have to look at the iteration number
to know which implementation the failure is from, which is less direct.
* If you make a mistake writing a typed test, the compiler errors can be
harder to digest, as the code is templatized.
* When using typed tests, you need to make sure you are testing against the
interface type, not the concrete types (in other words, you want to make
sure `implicit_cast<MyInterface*>(my_concrete_impl)` works, not just that
`my_concrete_impl` works). It's less likely to make mistakes in this area
when using value-parameterized tests.
If you think about it, it's already hard to make your code work when
I hope I didn't confuse you more. :-) If you don't mind, I'd suggest you to give
you know what other threads are doing. It's much harder, and
both approaches a try. Practice is a much better way to grasp the subtle
sometimes even impossible, to make your code work when you don't know
differences between the two tools. Once you have some concrete experience, you
what other threads are doing (remember that test methods can be added,
can much more easily decide which one to use the next time.
deleted, or modified after your test was written). If you want to run
the tests in parallel, you'd better run them in different processes.
## Why aren't Google Test assertions implemented using exceptions? ##
## My death tests became very slow - what happened?
Our original motivation was to be able to use Google Test in projects
In August 2008 we had to switch the default death test style from `fast` to
that disable exceptions. Later we realized some additional benefits
`threadsafe`, as the former is no longer safe now that threaded logging is the
of this approach:
default. This caused many death tests to slow down. Unfortunately this change
was necessary.
1. Throwing in a destructor is undefined behavior in C++. Not using exceptions means Google Test's assertions are safe to use in destructors.
1. The `EXPECT_*` family of macros will continue even after a failure, allowing multiple failures in a `TEST` to be reported in a single run. This is a popular feature, as in C++ the edit-compile-test cycle is usually quite long and being able to fixing more than one thing at a time is a blessing.
1. If assertions are implemented using exceptions, a test may falsely ignore a failure if it's caught by user code:
```c++
try{...ASSERT_TRUE(...)...}
catch(...){...}
```
The above code will pass even if the `ASSERT_TRUE` throws. While it's unlikely for someone to write this in a test, it's possible to run into this pattern when you write assertions in callbacks that are called by the code under test.
The downside of not using exceptions is that `ASSERT_*` (implemented
Please read [Fixing Failing Death Tests](death_test_styles.md) for what you can
using `return`) will only abort the current function, not the current
do.
`TEST`.
## Why do we use two different macros for tests with and without fixtures? ##
## I got some run-time errors about invalid proto descriptors when using `ProtocolMessageEquals`. Help!
Unfortunately, C++'s macro system doesn't allow us to use the same
**Note:**`ProtocolMessageEquals` and `ProtocolMessageEquiv` are *deprecated*
macro for both cases. One possibility is to provide only one macro
now. Please use `EqualsProto`, etc instead.
for tests with fixtures, and require the user to define an empty
fixture sometimes:
```c++
`ProtocolMessageEquals` and `ProtocolMessageEquiv` were redefined recently and
classFooTest:public::testing::Test{};
are now less tolerant on invalid protocol buffer definitions. In particular, if
you have a `foo.proto` that doesn't fully qualify the type of a protocol message
it references (e.g. `message<Bar>` where it should be `message<blah.Bar>`), you
will now get run-time errors like:
TEST_F(FooTest,DoesThis){...}
```
```
or
... descriptor.cc:...] Invalid proto descriptor for file "path/to/foo.proto":
```c++
... descriptor.cc:...] blah.MyMessage.my_field: ".Bar" is not defined.
typedef::testing::TestFooTest;
TEST_F(FooTest,DoesThat){...}
```
```
Yet, many people think this is one line toomany. :-) Our goal was to
If you see this, your `.proto` file is broken and needs to be fixed by making
make it really easy to write tests, so we tried to make simple tests
the types fully qualified. The new definition of `ProtocolMessageEquals` and
trivial to create. That means using a separate macro for such tests.
`ProtocolMessageEquiv` just happen to reveal your bug.
We think neither approach is ideal, yet either of them is reasonable.
## My death test modifies some state, but the change seems lost after the death test finishes. Why?
In the end, it probably doesn't matter much either way.
## Why don't we use structs as test fixtures? ##
Death tests (`EXPECT_DEATH`, etc) are executed in a sub-process s.t. the
expected crash won't kill the test program (i.e. the parent process). As a
result, any in-memory side effects they incur are observable in their respective
sub-processes, but not in the parent process. You can think of them as running
in a parallel universe, more or less.
We like to use structs only when representing passive data. This
In particular, if you use [gMock](http://go/gmock) and the death test statement
distinction between structs and classes is good for documenting the
invokes some mock methods, the parent process will think the calls have never
intent of the code's author. Since test fixtures have logic like
occurred. Therefore, you may want to move your `EXPECT_CALL` statements inside
`SetUp()` and `TearDown()`, they are better defined as classes.
the `EXPECT_DEATH` macro.
## Why are death tests implemented as assertions instead of using a test runner? ##
## EXPECT_EQ(htonl(blah), blah_blah) generates weird compiler errors in opt mode. Is this a googletest bug?
Our goal was to make death tests as convenient for a user as C++
Actually, the bug is in `htonl()`.
possibly allows. In particular:
* The runner-style requires to split the information into two pieces: the definition of the death test itself, and the specification for the runner on how to run the death test and what to expect. The death test would be written in C++, while the runner spec may or may not be. A user needs to carefully keep the two in sync. `ASSERT_DEATH(statement, expected_message)` specifies all necessary information in one place, in one language, without boilerplate code. It is very declarative.
According to `'man htonl'`, `htonl()` is a *function*, which means it's valid to
*`ASSERT_DEATH` has a similar syntax and error-reporting semantics as other Google Test assertions, and thus is easy to learn.
use `htonl` as a function pointer. However, in opt mode `htonl()` is defined as
*`ASSERT_DEATH` can be mixed with other assertions and other logic at your will. You are not limited to one death test per test method. For example, you can write something like:
a *macro*, which breaks this usage.
```c++
if(FooCondition()){
ASSERT_DEATH(Bar(),"blah");
}else{
ASSERT_EQ(5,Bar());
}
```
If you prefer one death test per test method, you can write your tests in that style too, but we don't want to impose that on the users. The fewer artificial limitations the better.
*`ASSERT_DEATH` can reference local variables in the current function, and you can decide how many death tests you want based on run-time information. For example,
```c++
constintcount=GetCount();// Only known at run time.
for(inti=1;i<=count;i++){
ASSERT_DEATH({
double*buffer=newdouble[i];
...initializesbuffer...
Foo(buffer,i)
},"blah blah");
}
```
The runner-based approach tends to be more static and less flexible, or requires more user effort to get this kind of flexibility.
Another interesting thing about `ASSERT_DEATH` is that it calls `fork()`
Worse, the macro definition of `htonl()` uses a `gcc` extension and is *not*
to create a child process to run the death test. This is lightening
standard C++. That hacky implementation has some ad hoc limitations. In
fast, as `fork()` uses copy-on-write pages and incurs almost zero
particular, it prevents you from writing `Foo<sizeof(htonl(x))>()`, where `Foo`
overhead, and the child process starts from the user-supplied
is a template that has an integral argument.
statement directly, skipping all global and local initialization and
any code leading to the given statement. If you launch the child
process from scratch, it can take seconds just to load everything and
start running if the test links to many libraries dynamically.
## My death test modifies some state, but the change seems lost after the death test finishes. Why? ##
The implementation of `EXPECT_EQ(a, b)` uses `sizeof(... a ...)` inside a
template argument, and thus doesn't compile in opt mode when `a` contains a call
to `htonl()`. It is difficult to make `EXPECT_EQ` bypass the `htonl()` bug, as
the solution must work with different compilers on various platforms.
Death tests (`EXPECT_DEATH`, etc) are executed in a sub-process s.t. the
`htonl()` has some other problems as described in `//util/endian/endian.h`,
expected crash won't kill the test program (i.e. the parent process). As a
which defines `ghtonl()` to replace it. `ghtonl()` does the same thing `htonl()`
result, any in-memory side effects they incur are observable in their
does, only without its problems. We suggest you to use `ghtonl()` instead of
respective sub-processes, but not in the parent process. You can think of them
`htonl()`, both in your tests and production code.
as running in a parallel universe, more or less.
`//util/endian/endian.h` also defines `ghtons()`, which solves similar problems
in `htons()`.
## The compiler complains about "undefined references" to some static const member variables, but I did define them in the class body. What's wrong? ##
Don't forget to add `//util/endian` to the list of dependencies in the `BUILD`
file wherever `ghtonl()` and `ghtons()` are used. The library consists of a
single header file and will not bloat your binary.
## The compiler complains about "undefined references" to some static const member variables, but I did define them in the class body. What's wrong?
If your class has a static data member:
If your class has a static data member:
...
@@ -343,23 +209,18 @@ class Foo {
...
@@ -343,23 +209,18 @@ class Foo {
};
};
```
```
You also need to define it _outside_ of the class body in `foo.cc`:
You also need to define it *outside* of the class body in `foo.cc`:
```c++
```c++
constintFoo::kBar;// No initializer here.
constintFoo::kBar;// No initializer here.
```
```
Otherwise your code is **invalid C++**, and may break in unexpected ways. In
Otherwise your code is **invalid C++**, and may break in unexpected ways. In
particular, using it in Google Test comparison assertions (`EXPECT_EQ`, etc)
particular, using it in googletest comparison assertions (`EXPECT_EQ`, etc) will
will generate an "undefined reference" linker error.
generate an "undefined reference" linker error. The fact that "it used to work"
doesn't mean it's valid. It just means that you were lucky. :-)
## I have an interface that has several implementations. Can I write a set of tests once and repeat them over all the implementations? ##
Google Test doesn't yet have good support for this kind of tests, or
data-driven tests in general. We hope to be able to make improvements in this
area soon.
## Can I derive a test fixture from another? ##
## Can I derive a test fixture from another?
Yes.
Yes.
...
@@ -369,33 +230,35 @@ cases may want to use the same or slightly different fixtures. For example, you
...
@@ -369,33 +230,35 @@ cases may want to use the same or slightly different fixtures. For example, you
may want to make sure that all of a GUI library's test cases don't leak
may want to make sure that all of a GUI library's test cases don't leak
important system resources like fonts and brushes.
important system resources like fonts and brushes.
In Google Test, you share a fixture among test cases by putting the shared
In googletest, you share a fixture among test cases by putting the shared logic
logic in a base test fixture, then deriving from that base a separate fixture
in a base test fixture, then deriving from that base a separate fixture for each
for each test case that wants to use this common logic. You then use `TEST_F()`
test case that wants to use this common logic. You then use `TEST_F()` to write
to write tests using each derived fixture.
tests using each derived fixture.
Typically, your code looks like this:
Typically, your code looks like this:
```c++
```c++
// Defines a base test fixture.
// Defines a base test fixture.
classBaseTest:public::testing::Test{
classBaseTest:public::testing::Test{
protected:
protected:
...
...
};
};
// Derives a fixture FooTest from BaseTest.
// Derives a fixture FooTest from BaseTest.
classFooTest:publicBaseTest{
classFooTest:publicBaseTest{
protected:
protected:
virtualvoidSetUp(){
voidSetUp()override{
BaseTest::SetUp();// Sets up the base fixture first.
BaseTest::SetUp();// Sets up the base fixture first.
...additionalset-upwork...
...additionalset-upwork...
}
}
virtualvoidTearDown(){
...clean-upworkforFooTest...
voidTearDown()override{
BaseTest::TearDown();// Remember to tear down the base fixture
...clean-upworkforFooTest...
// after cleaning up FooTest!
BaseTest::TearDown();// Remember to tear down the base fixture
## My compiler complains "void value not ignored as it ought to be." What does this mean? ##
## My compiler complains "void value not ignored as it ought to be." What does this mean?
You're probably using an `ASSERT_*()` in a function that doesn't return `void`.
You're probably using an `ASSERT_*()` in a function that doesn't return `void`.
`ASSERT_*()` can only be used in `void` functions.
`ASSERT_*()` can only be used in `void` functions, due to exceptions being
disabled by our build system. Please see more details
[here](advanced.md#assertion-placement).
## My death test hangs (or seg-faults). How do I fix it? ##
## My death test hangs (or seg-faults). How do I fix it?
In Google Test, death tests are run in a child process and the way they work is
In googletest, death tests are run in a child process and the way they work is
delicate. To write death tests you really need to understand how they work.
delicate. To write death tests you really need to understand how they work.
Please make sure you have read this.
Please make sure you have read [this](advanced.md#how-it-works).
In particular, death tests don't like having multiple threads in the parent
In particular, death tests don't like having multiple threads in the parent
process. So the first thing you can try is to eliminate creating threads
process. So the first thing you can try is to eliminate creating threads outside
outside of `EXPECT_DEATH()`.
of `EXPECT_DEATH()`. For example, you may want to use [mocks](http://go/gmock)
or fake objects instead of real ones in your tests.
Sometimes this is impossible as some library you must use may be creating
Sometimes this is impossible as some library you must use may be creating
threads before `main()` is even reached. In this case, you can try to minimize
threads before `main()` is even reached. In this case, you can try to minimize
the chance of conflicts by either moving as many activities as possible inside
the chance of conflicts by either moving as many activities as possible inside
`EXPECT_DEATH()` (in the extreme case, you want to move everything inside), or
`EXPECT_DEATH()` (in the extreme case, you want to move everything inside), or
leaving as few things as possible in it. Also, you can try to set the death
leaving as few things as possible in it. Also, you can try to set the death test
test style to `"threadsafe"`, which is safer but slower, and see if it helps.
style to `"threadsafe"`, which is safer but slower, and see if it helps.
If you go with thread-safe death tests, remember that they rerun the test
If you go with thread-safe death tests, remember that they rerun the test
program from the beginning in the child process. Therefore make sure your
program from the beginning in the child process. Therefore make sure your
...
@@ -441,28 +307,52 @@ In the end, this boils down to good concurrent programming. You have to make
...
@@ -441,28 +307,52 @@ In the end, this boils down to good concurrent programming. You have to make
sure that there is no race conditions or dead locks in your program. No silver
sure that there is no race conditions or dead locks in your program. No silver
bullet - sorry!
bullet - sorry!
## Should I use the constructor/destructor of the test fixture or the set-up/tear-down function? ##
## Should I use the constructor/destructor of the test fixture or SetUp()/TearDown()?
The first thing to remember is that Google Test does not reuse the
The first thing to remember is that googletest does **not** reuse the same test
same test fixture object across multiple tests. For each `TEST_F`,
fixture object across multiple tests. For each `TEST_F`, googletest will create
Google Test will create a fresh test fixture object, _immediately_
a **fresh** test fixture object, immediately call `SetUp()`, run the test body,
call `SetUp()`, run the test body, call `TearDown()`, and then
call `TearDown()`, and then delete the test fixture object.
_immediately_ delete the test fixture object.
When you need to write per-test set-up and tear-down logic, you have
When you need to write per-test set-up and tear-down logic, you have the choice
the choice between using the test fixture constructor/destructor or
between using the test fixture constructor/destructor or `SetUp()/TearDown()`.
`SetUp()/TearDown()`. The former is usually preferred, as it has the
The former is usually preferred, as it has the following benefits:
following benefits:
* By initializing a member variable in the constructor, we have the option to make it `const`, which helps prevent accidental changes to its value and makes the tests more obviously correct.
* By initializing a member variable in the constructor, we have the option to
* In case we need to subclass the test fixture class, the subclass' constructor is guaranteed to call the base class' constructor first, and the subclass' destructor is guaranteed to call the base class' destructor afterward. With `SetUp()/TearDown()`, a subclass may make the mistake of forgetting to call the base class' `SetUp()/TearDown()` or call them at the wrong moment.
make it `const`, which helps prevent accidental changes to its value and
makes the tests more obviously correct.
* In case we need to subclass the test fixture class, the subclass'
constructor is guaranteed to call the base class' constructor *first*, and
the subclass' destructor is guaranteed to call the base class' destructor
*afterward*. With `SetUp()/TearDown()`, a subclass may make the mistake of
forgetting to call the base class' `SetUp()/TearDown()` or call them at the
wrong time.
You may still want to use `SetUp()/TearDown()` in the following rare cases:
You may still want to use `SetUp()/TearDown()` in the following rare cases:
* If the tear-down operation could throw an exception, you must use `TearDown()` as opposed to the destructor, as throwing in a destructor leads to undefined behavior and usually will kill your program right away. Note that many standard libraries (like STL) may throw when exceptions are enabled in the compiler. Therefore you should prefer `TearDown()` if you want to write portable tests that work with or without exceptions.
* The assertion macros throw an exception when flag `--gtest_throw_on_failure` is specified. Therefore, you shouldn't use Google Test assertions in a destructor if you plan to run your tests with this flag.
* In a constructor or destructor, you cannot make a virtual function call on this object. (You can call a method declared as virtual, but it will be statically bound.) Therefore, if you need to call a method that will be overridden in a derived class, you have to use `SetUp()/TearDown()`.
## The compiler complains "no matching function to call" when I use ASSERT\_PREDn. How do I fix it? ##
* In the body of a constructor (or destructor), it's not possible to use the
`ASSERT_xx` macros. Therefore, if the set-up operation could cause a fatal
test failure that should prevent the test from running, it's necessary to
use a `CHECK` macro or to use `SetUp()` instead of a constructor.
* If the tear-down operation could throw an exception, you must use
`TearDown()` as opposed to the destructor, as throwing in a destructor leads
to undefined behavior and usually will kill your program right away. Note
that many standard libraries (like STL) may throw when exceptions are
enabled in the compiler. Therefore you should prefer `TearDown()` if you
want to write portable tests that work with or without exceptions.
* The googletest team is considering making the assertion macros throw on
platforms where exceptions are enabled (e.g. Windows, Mac OS, and Linux
client-side), which will eliminate the need for the user to propagate
failures from a subroutine to its caller. Therefore, you shouldn't use
googletest assertions in a destructor if your code could run on such a
platform.
* In a constructor or destructor, you cannot make a virtual function call on
this object. (You can call a method declared as virtual, but it will be
statically bound.) Therefore, if you need to call a method that will be
overridden in a derived class, you have to use `SetUp()/TearDown()`.
## The compiler complains "no matching function to call" when I use ASSERT_PRED*. How do I fix it?
If the predicate function you use in `ASSERT_PRED*` or `EXPECT_PRED*` is
If the predicate function you use in `ASSERT_PRED*` or `EXPECT_PRED*` is
overloaded or a template, the compiler will have trouble figuring out which
overloaded or a template, the compiler will have trouble figuring out which
(The stuff inside the angled brackets for the `static_cast` operator is the
(The stuff inside the angled brackets for the `static_cast` operator is the type
type of the function pointer for the `int`-version of `IsPositive()`.)
of the function pointer for the `int`-version of `IsPositive()`.)
As another example, when you have a template function
As another example, when you have a template function
...
@@ -522,72 +413,76 @@ following won't compile:
...
@@ -522,72 +413,76 @@ following won't compile:
ASSERT_PRED2(GreaterThan<int,int>,5,0);
ASSERT_PRED2(GreaterThan<int,int>,5,0);
```
```
as the C++ pre-processor thinks you are giving `ASSERT_PRED2` 4 arguments, which
as the C++ pre-processor thinks you are giving `ASSERT_PRED2` 4 arguments,
is one more than expected. The workaround is to wrap the predicate function in
which is one more than expected. The workaround is to wrap the predicate
parentheses:
function in parentheses:
```c++
```c++
ASSERT_PRED2((GreaterThan<int,int>),5,0);
ASSERT_PRED2((GreaterThan<int,int>),5,0);
```
```
## My compiler complains about "ignoring return value" when I call RUN\_ALL\_TESTS(). Why? ##
## My compiler complains about "ignoring return value" when I call RUN_ALL_TESTS(). Why?
Some people had been ignoring the return value of `RUN_ALL_TESTS()`. That is,
Some people had been ignoring the return value of `RUN_ALL_TESTS()`. That is,
instead of
instead of
```c++
```c++
returnRUN_ALL_TESTS();
returnRUN_ALL_TESTS();
```
```
they write
they write
```c++
```c++
RUN_ALL_TESTS();
RUN_ALL_TESTS();
```
```
This is wrong and dangerous. A test runner needs to see the return value of
This is **wrong and dangerous**. The testing services needs to see the return
`RUN_ALL_TESTS()` in order to determine if a test has passed. If your`main()`
value of `RUN_ALL_TESTS()` in order to determine if a test has passed. If your
function ignores it, your test will be considered successful even if it has a
`main()`function ignores it, your test will be considered successful even if it
Google Test assertion failure. Very bad.
has a googletest assertion failure. Very bad.
To help the users avoid this dangerous bug, the implementation of
We have decided to fix this (thanks to Michael Chastain for the idea). Now, your
`RUN_ALL_TESTS()` causes gcc to raise this warning, when the return value is
code will no longer be able to ignore `RUN_ALL_TESTS()` when compiled with
ignored. If you see this warning, the fix is simple: just make sure its value
`gcc`. If you do so, you'll get a compiler error.
is used as the return value of `main()`.
## My compiler complains that a constructor (or destructor) cannot return a value. What's going on? ##
If you see the compiler complaining about you ignoring the return value of
`RUN_ALL_TESTS()`, the fix is simple: just make sure its value is used as the
return value of `main()`.
But how could we introduce a change that breaks existing tests? Well, in this
case, the code was already broken in the first place, so we didn't break it. :-)
## My compiler complains that a constructor (or destructor) cannot return a value. What's going on?
Due to a peculiarity of C++, in order to support the syntax for streaming
Due to a peculiarity of C++, in order to support the syntax for streaming
messages to an `ASSERT_*`, e.g.
messages to an `ASSERT_*`, e.g.
```c++
```c++
ASSERT_EQ(1,Foo())<<"blah blah"<<foo;
ASSERT_EQ(1,Foo())<<"blah blah"<<foo;
```
```
we had to give up using `ASSERT*` and `FAIL*` (but not `EXPECT*` and
we had to give up using `ASSERT*` and `FAIL*` (but not `EXPECT*` and
`ADD_FAILURE*`) in constructors and destructors. The workaround is to move the
`ADD_FAILURE*`) in constructors and destructors. The workaround is to move the
content of your constructor/destructor to a private void member function, or
content of your constructor/destructor to a private void member function, or
switch to `EXPECT_*()` if that works. This section in the user's guide explains
switch to `EXPECT_*()` if that works. This
it.
[section](advanced.md#assertion-placement) in the user's guide explains it.
## My set-up function is not called. Why? ##
## My SetUp() function is not called. Why?
C++ is case-sensitive. It should be spelled as `SetUp()`. Did you
C++ is case-sensitive. Did you spell it as `Setup()`?
spell it as `Setup()`?
Similarly, sometimes people spell `SetUpTestCase()` as `SetupTestCase()` and
Similarly, sometimes people spell `SetUpTestCase()` as `SetupTestCase()` and
wonder why it's never called.
wonder why it's never called.
## How do I jump to the line of a failure in Emacs directly? ##
## How do I jump to the line of a failure in Emacs directly?
googletest's failure message format is understood by Emacs and many other IDEs,
like acme and XCode. If a googletest message is in a compilation buffer in
Emacs, then it's clickable.
Google Test's failure message format is understood by Emacs and many other
IDEs, like acme and XCode. If a Google Test message is in a compilation buffer
in Emacs, then it's clickable. You can now hit `enter` on a message to jump to
the corresponding source code, or use `C-x `` to jump to the next failure.
## I have several test cases which share the same test fixture logic, do I have to define a new test fixture class for each of them? This seems pretty tedious. ##
## I have several test cases which share the same test fixture logic, do I have to define a new test fixture class for each of them? This seems pretty tedious.
## The Google Test output is buried in a whole bunch of log messages. What do I do? ##
## googletest output is buried in a whole bunch of LOG messages. What do I do?
The Google Test output is meant to be a concise and human-friendly report. If
The googletest output is meant to be a concise and human-friendly report. If
your test generates textual output itself, it will mix with the Google Test
your test generates textual output itself, it will mix with the googletest
output, making it hard to read. However, there is an easy solution to this
output, making it hard to read. However, there is an easy solution to this
problem.
problem.
Since most log messages go to stderr, we decided to let Google Test output go
Since `LOG` messages go to stderr, we decided to let googletest output go to
to stdout. This way, you can easily separate the two using redirection. For
stdout. This way, you can easily separate the two using redirection. For
example:
example:
```
./my_test > googletest_output.txt
```
## Why should I prefer test fixtures over global variables? ##
There are several good reasons:
1. It's likely your test needs to change the states of its global variables. This makes it difficult to keep side effects from escaping one test and contaminating others, making debugging difficult. By using fixtures, each test has a fresh set of variables that's different (but with the same names). Thus, tests are kept independent of each other.
1. Global variables pollute the global namespace.
1. Test fixtures can be reused via subclassing, which cannot be done easily with global variables. This is useful if many test cases have something in common.
## How do I test private class members without writing FRIEND\_TEST()s? ##
You should try to write testable code, which means classes should be easily
```shell
tested from their public interface. One way to achieve this is the Pimpl idiom:
$ ./my_test > gtest_output.txt
you move all private members of a class into a helper class, and make all
members of the helper class public.
You have several other options that don't require using `FRIEND_TEST`:
* Write the tests as members of the fixture class:
```c++
class Foo {
friend class FooTest;
...
};
class FooTest : public ::testing::Test {
protected:
...
void Test1() {...} // This accesses private members of class Foo.
void Test2() {...} // So does this one.
};
TEST_F(FooTest, Test1) {
Test1();
}
TEST_F(FooTest, Test2) {
Test2();
}
```
```
* In the fixture class, write accessors for the tested class' private members, then use the accessors in your tests:
```c++
class Foo {
friend class FooTest;
...
};
class FooTest : public ::testing::Test {
protected:
...
T1 get_private_member1(Foo* obj) {
return obj->private_member1_;
}
};
TEST_F(FooTest, Test1) {
## Why should I prefer test fixtures over global variables?
...
get_private_member1(x)
...
}
```
* If the methods are declared **protected**, you can change their access level in a test-only subclass:
```c++
class YourClass {
...
protected: // protected access for testability.
int DoSomethingReturningInt();
...
};
// in the your_class_test.cc file:
class TestableYourClass : public YourClass {
...
public: using YourClass::DoSomethingReturningInt; // changes access rights
## I have a fixture class Foo, but TEST\_F(Foo, Bar) gives me error "no matching function for call to Foo::Foo()". Why? ##
Googletest needs to be able to create objects of your test fixture class, so it
must have a default constructor. Normally the compiler will define one for you.
However, there are cases where you have to define your own:
Google Test needs to be able to create objects of your test fixture class, so
* If you explicitly declare a non-default constructor for class `FooTest`
it must have a default constructor. Normally the compiler will define one for
(`DISALLOW_EVIL_CONSTRUCTORS()` does this), then you need to define a
you. However, there are cases where you have to define your own:
default constructor, even if it would be empty.
* If you explicitly declare a non-default constructor for class `Foo`, then you need to define a default constructor, even if it would be empty.
* If `FooTest` has a const non-static data member, then you have to define the
* If `Foo` has a const non-static data member, then you have to define the default constructor _and_ initialize the const member in the initializer list of the constructor. (Early versions of `gcc` doesn't force you to initialize the const member. It's a bug that has been fixed in `gcc 4`.)
default constructor *and* initialize the const member in the initializer
list of the constructor. (Early versions of `gcc` doesn't force you to
initialize the const member. It's a bug that has been fixed in `gcc 4`.)
## Why does ASSERT\_DEATH complain about previous threads that were already joined? ##
## Why does ASSERT_DEATH complain about previous threads that were already joined?
With the Linux pthread library, there is no turning back once you cross the
With the Linux pthread library, there is no turning back once you cross the line
line from single thread to multiple threads. The first time you create a
from single thread to multiple threads. The first time you create a thread, a
thread, a manager thread is created in addition, so you get 3, not 2, threads.
manager thread is created in addition, so you get 3, not 2, threads. Later when
Later when the thread you create joins the main thread, the thread count
the thread you create joins the main thread, the thread count decrements by 1,
decrements by 1, but the manager thread will never be killed, so you still have
but the manager thread will never be killed, so you still have 2 threads, which
2 threads, which means you cannot safely run a death test.
means you cannot safely run a death test.
The new NPTL thread library doesn't suffer from this problem, as it doesn't
The new NPTL thread library doesn't suffer from this problem, as it doesn't
create a manager thread. However, if you don't control which machine your test
create a manager thread. However, if you don't control which machine your test
runs on, you shouldn't depend on this.
runs on, you shouldn't depend on this.
## Why does Google Test require the entire test case, instead of individual tests, to be named FOODeathTest when it uses ASSERT\_DEATH? ##
## Why does googletest require the entire test case, instead of individual tests, to be named *DeathTest when it uses ASSERT_DEATH?
Google Test does not interleave tests from different test cases. That is, it
googletest does not interleave tests from different test cases. That is, it runs
runs all tests in one test case first, and then runs all tests in the next test
all tests in one test case first, and then runs all tests in the next test case,
case, and so on. Google Test does this because it needs to set up a test case
and so on. googletest does this because it needs to set up a test case before
before the first test in it is run, and tear it down afterwords. Splitting up
the first test in it is run, and tear it down afterwords. Splitting up the test
the test case would require multiple set-up and tear-down processes, which is
case would require multiple set-up and tear-down processes, which is inefficient
inefficient and makes the semantics unclean.
and makes the semantics unclean.
If we were to determine the order of tests based on test name instead of test
If we were to determine the order of tests based on test name instead of test
case name, then we would have a problem with the following situation:
case name, then we would have a problem with the following situation:
...
@@ -897,7 +646,7 @@ interleave tests from different test cases, we need to run all tests in the
...
@@ -897,7 +646,7 @@ interleave tests from different test cases, we need to run all tests in the
`FooTest` case before running any test in the `BarTest` case. This contradicts
`FooTest` case before running any test in the `BarTest` case. This contradicts
with the requirement to run `BarTest.DefDeathTest` before `FooTest.Uvw`.
with the requirement to run `BarTest.DefDeathTest` before `FooTest.Uvw`.
## But I don't like calling my entire test case FOODeathTest when it contains both death tests and non-death tests. What do I do? ##
## But I don't like calling my entire test case \*DeathTest when it contains both death tests and non-death tests. What do I do?
You don't have to, but if you like, you may split up the test case into
You don't have to, but if you like, you may split up the test case into
`FooTest` and `FooDeathTest`, where the names make it clear that they are
`FooTest` and `FooDeathTest`, where the names make it clear that they are
...
@@ -909,119 +658,81 @@ class FooTest : public ::testing::Test { ... };
...
@@ -909,119 +658,81 @@ class FooTest : public ::testing::Test { ... };
TEST_F(FooTest,Abc){...}
TEST_F(FooTest,Abc){...}
TEST_F(FooTest,Def){...}
TEST_F(FooTest,Def){...}
typedef FooTest FooDeathTest;
usingFooDeathTest=FooTest;
TEST_F(FooDeathTest,Uvw){...EXPECT_DEATH(...)...}
TEST_F(FooDeathTest,Uvw){...EXPECT_DEATH(...)...}
TEST_F(FooDeathTest,Xyz){...ASSERT_DEATH(...)...}
TEST_F(FooDeathTest,Xyz){...ASSERT_DEATH(...)...}
```
```
## The compiler complains about "no match for 'operator<<'" when I use an assertion. What gives? ##
## googletest prints the LOG messages in a death test's child process only when the test fails. How can I see the LOG messages when the death test succeeds?
Printing the LOG messages generated by the statement inside `EXPECT_DEATH()`
makes it harder to search for real problems in the parent's log. Therefore,
googletest only prints them when the death test has failed.
If you really need to see such LOG messages, a workaround is to temporarily
break the death test (e.g. by changing the regex pattern it is expected to
match). Admittedly, this is a hack. We'll consider a more permanent solution
after the fork-and-exec-style death tests are implemented.
## The compiler complains about "no match for 'operator<<'" when I use an assertion. What gives?
If you use a user-defined type `FooType` in an assertion, you must make sure
If you use a user-defined type `FooType` in an assertion, you must make sure
there is an `std::ostream& operator<<(std::ostream&, const FooType&)` function
there is an `std::ostream& operator<<(std::ostream&, const FooType&)` function
defined such that we can print a value of `FooType`.
defined such that we can print a value of `FooType`.
In addition, if `FooType` is declared in a name space, the `<<` operator also
In addition, if `FooType` is declared in a name space, the `<<` operator also
needs to be defined in the _same_ name space.
needs to be defined in the *same* name space. See go/totw/49 for details.
## How do I suppress the memory leak messages on Windows? ##
## How do I suppress the memory leak messages on Windows?
Since the statically initialized Google Test singleton requires allocations on
Since the statically initialized googletest singleton requires allocations on
the heap, the Visual C++ memory leak detector will report memory leaks at the
the heap, the Visual C++ memory leak detector will report memory leaks at the
end of the program run. The easiest way to avoid this is to use the
end of the program run. The easiest way to avoid this is to use the
`_CrtMemCheckpoint` and `_CrtMemDumpAllObjectsSince` calls to not report any
`_CrtMemCheckpoint` and `_CrtMemDumpAllObjectsSince` calls to not report any
statically initialized heap objects. See MSDN for more details and additional
statically initialized heap objects. See MSDN for more details and additional
heap check/debug routines.
heap check/debug routines.
## I am building my project with Google Test in Visual Studio and all I'm getting is a bunch of linker errors (or warnings). Help! ##
You may get a number of the following linker error or warnings if you
attempt to link your test project with the Google Test library when
your project and the are not built using the same compiler settings.
* LNK2005: symbol already defined in object
* LNK4217: locally defined symbol 'symbol' imported in function 'function'
* LNK4049: locally defined symbol 'symbol' imported
The Google Test project (gtest.vcproj) has the Runtime Library option
set to /MT (use multi-threaded static libraries, /MTd for debug). If
your project uses something else, for example /MD (use multi-threaded
DLLs, /MDd for debug), you need to change the setting in the Google
Test project to match your project's.
To update this setting open the project properties in the Visual
Studio IDE then select the branch Configuration Properties | C/C++ |
Code Generation and change the option "Runtime Library". You may also try
using gtest-md.vcproj instead of gtest.vcproj.
## I put my tests in a library and Google Test doesn't run them. What's happening? ##
Have you read a
[warning](primer.md#important-note-for-visual-c-users) on
the Google Test Primer page?
## I want to use Google Test with Visual Studio but don't know where to start. ##
Many people are in your position and one of them posted his solution to our mailing list.
## I am seeing compile errors mentioning std::type\_traits when I try to use Google Test on Solaris. ##
Google Test uses parts of the standard C++ library that SunStudio does not support.
Our users reported success using alternative implementations. Try running the build after running this command:
Therefore we strongly advise against the practice, and Google Test doesn't
provide a way to do it.
In general, the recommended way to cause the code to behave
differently under test is [dependency injection](http://jamesshore.com/Blog/Dependency-Injection-Demystified.html).
You can inject different functionality from the test and from the
production code. Since your production code doesn't link in the
for-test logic at all, there is no danger in accidentally running it.
However, if you _really_, _really_, _really_ have no choice, and if
you follow the rule of ending your test program names with `_test`,
you can use the _horrible_ hack of sniffing your executable name
(`argv[0]` in `main()`) to know whether the code is under test.
## Google Test defines a macro that clashes with one defined by another library. How do I deal with that? ##
In C++, macros don't obey namespaces. Therefore two libraries that
both define a macro of the same name will clash if you `#include` both
definitions. In case a Google Test macro clashes with another
library, you can force Google Test to rename its macro to avoid the
conflict.
Specifically, if both Google Test and some other code define macro
`FOO`, you can add
```
-DGTEST_DONT_DEFINE_FOO=1
```
to the compiler flags to tell Google Test to change the macro's name
from `FOO` to `GTEST_FOO`. For example, with `-DGTEST_DONT_DEFINE_TEST=1`, you'll need to write
```c++
GTEST_TEST(SomeTest, DoesThis) { ... }
```
instead of
```c++
TEST(SomeTest, DoesThis) { ... }
```
in order to define a test.
Currently, the following `TEST`, `FAIL`, `SUCCEED`, and the basic comparison assertion macros can have . You can see the full list of covered macros [here](../include/gtest/gtest.h). More information can be found in the "Avoiding Macro Name Clashes" section of the README file.
## How can my code detect if it is running in a test?
If you write code that sniffs whether it's running in a test and does different
things accordingly, you are leaking test-only logic into production code and
there is no easy way to ensure that the test-only code paths aren't run by
mistake in production. Such cleverness also leads to
[Heisenbugs](https://en.wikipedia.org/wiki/Heisenbug). Therefore we strongly
advise against the practice, and googletest doesn't provide a way to do it.
In general, the recommended way to cause the code to behave differently under
test is [Dependency Injection](http://go/dependency-injection). You can inject
different functionality from the test and from the production code. Since your
production code doesn't link in the for-test logic at all (the
[`testonly`](http://go/testonly) attribute for BUILD targets helps to ensure
that), there is no danger in accidentally running it.
However, if you *really*, *really*, *really* have no choice, and if you follow
the rule of ending your test program names with `_test`, you can use the
*horrible* hack of sniffing your executable name (`argv[0]` in `main()`) to know
whether the code is under test.
## Is it OK if I have two separate `TEST(Foo, Bar)` test methods defined in different namespaces? ##
## How do I temporarily disable a test?
If you have a broken test that you cannot fix right away, you can add the
DISABLED_ prefix to its name. This will exclude it from execution. This is
better than commenting out the code or using #if 0, as disabled tests are still
compiled (and thus won't rot).
To include disabled tests in test execution, just invoke the test program with
the --gtest_also_run_disabled_tests flag.
## Is it OK if I have two separate `TEST(Foo, Bar)` test methods defined in different namespaces?
Yes.
Yes.
The rule is **all test methods in the same test case must use the same fixture class**. This means that the following is **allowed** because both tests use the same fixture class (`::testing::Test`).
The rule is **all test methods in the same test case must use the same fixture
class.** This means that the following is **allowed** because both tests use the
However, the following code is **not allowed** and will produce a runtime error from Google Test because the test methods are using different test fixture classes with the same test case name.
However, the following code is **not allowed** and will produce a runtime error
from googletest because the test methods are using different test fixture
## How do I build Google Testing Framework with Xcode 4? ##
If you try to build Google Test's Xcode project with Xcode 4.0 or later, you may encounter an error message that looks like
"Missing SDK in target gtest\_framework: /Developer/SDKs/MacOSX10.4u.sdk". That means that Xcode does not support the SDK the project is targeting. See the Xcode section in the [README](../README.md) file on how to resolve this.
## How do I easily discover the flags needed for GoogleTest? ##
GoogleTest (and GoogleMock) now support discovering all necessary flags using pkg-config.
See the [pkg-config guide](Pkgconfig.md) on how you can easily discover all compiler and
linker flags using pkg-config.
## My question is not covered in your FAQ! ##
If you cannot find the answer to your question in this FAQ, there are
some other resources you can use:
1. read other [wiki pages](../docs),
1. search the mailing list [archive](https://groups.google.com/forum/#!forum/googletestframework),
1. ask it on [googletestframework@googlegroups.com](mailto:googletestframework@googlegroups.com) and someone will answer it (to prevent spam, we require you to join the [discussion group](http://groups.google.com/group/googletestframework) before you can post.).
Please note that creating an issue in the
[issue tracker](https://github.com/google/googletest/issues) is _not_
a good way to get your answer, as it is monitored infrequently by a
very small number of people.
When asking a question, it's helpful to provide as much of the
following information as possible (people cannot help you if there's
not enough information in your question):
* the version (or the commit hash if you check out from Git directly) of Google Test you use (Google Test is under active development, so it's possible that your problem has been solved in a later version),
* your operating system,
* the name and version of your compiler,
* the complete command line flags you give to your compiler,
* the complete compiler error messages (if the question is about compilation),
* the _actual_ code (ideally, a minimal but complete program) that has the problem you encounter.
@@ -197,7 +198,7 @@ objects, you should use `ASSERT_EQ`.
...
@@ -197,7 +198,7 @@ objects, you should use `ASSERT_EQ`.
When doing pointer comparisons use `*_EQ(ptr, nullptr)` and `*_NE(ptr, nullptr)`
When doing pointer comparisons use `*_EQ(ptr, nullptr)` and `*_NE(ptr, nullptr)`
instead of `*_EQ(ptr, NULL)` and `*_NE(ptr, NULL)`. This is because `nullptr` is
instead of `*_EQ(ptr, NULL)` and `*_NE(ptr, NULL)`. This is because `nullptr` is
typed while `NULL` is not. See [FAQ](faq#Why_does_googletest_support_EXPECT_EQ)
typed while `NULL` is not. See [FAQ](faq.md#why-does-google-test-support-expect_eqnull-ptr-and-assert_eqnull-ptr-but-not-expect_nenull-ptr-and-assert_nenull-ptr)
for more details.
for more details.
If you're working with floating point numbers, you may want to use the floating
If you're working with floating point numbers, you may want to use the floating
...
@@ -322,7 +323,7 @@ To create a fixture:
...
@@ -322,7 +323,7 @@ To create a fixture:
1. If necessary, write a destructor or `TearDown()` function to release any
1. If necessary, write a destructor or `TearDown()` function to release any
resources you allocated in `SetUp()` . To learn when you should use the
resources you allocated in `SetUp()` . To learn when you should use the
constructor/destructor and when you should use `SetUp()/TearDown()`, read
constructor/destructor and when you should use `SetUp()/TearDown()`, read
this [FAQ](faq#CtorVsSetUp) entry.
this [FAQ](faq.md#should-i-use-the-constructordestructor-of-the-test-fixture-or-the-set-uptear-down-function) entry.
1. If needed, define subroutines for your tests to share.
1. If needed, define subroutines for your tests to share.
When using a fixture, use `TEST_F()` instead of `TEST()` as it allows you to
When using a fixture, use `TEST_F()` instead of `TEST()` as it allows you to
...
@@ -436,6 +437,7 @@ When these tests run, the following happens:
...
@@ -436,6 +437,7 @@ When these tests run, the following happens:
**Availability**: Linux, Windows, Mac.
**Availability**: Linux, Windows, Mac.
## Invoking the Tests
## Invoking the Tests
`TEST()` and `TEST_F()` implicitly register their tests with googletest. So,
`TEST()` and `TEST_F()` implicitly register their tests with googletest. So,
...
@@ -544,6 +546,7 @@ int main(int argc, char **argv) {
...
@@ -544,6 +546,7 @@ int main(int argc, char **argv) {
}
}
```
```
The `::testing::InitGoogleTest()` function parses the command line for
The `::testing::InitGoogleTest()` function parses the command line for
googletest flags, and removes all recognized flags. This allows the user to
googletest flags, and removes all recognized flags. This allows the user to
control a test program's behavior via various flags, which we'll cover in
control a test program's behavior via various flags, which we'll cover in
...
@@ -560,6 +563,7 @@ gtest\_main library and you are good to go.
...
@@ -560,6 +563,7 @@ gtest\_main library and you are good to go.
NOTE: `ParseGUnitFlags()` is deprecated in favor of `InitGoogleTest()`.
NOTE: `ParseGUnitFlags()` is deprecated in favor of `InitGoogleTest()`.
## Known Limitations
## Known Limitations
* Google Test is designed to be thread-safe. The implementation is thread-safe
* Google Test is designed to be thread-safe. The implementation is thread-safe
