| `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_NO_THROW(`_statement_`);`| `EXPECT_NO_THROW(`_statement_`);`| _statement_ doesn't throw any exception |
| `ASSERT_PRED1(pred1, | `EXPECT_PRED1(pred1, | `pred1(val1)` is true |
: val1);` : val1);` : :
| `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
_val1_, _val2_, ..., and _valn_ are its arguments. The assertion succeeds
if the predicate returns `true` when applied to the given arguments, and fails
In the above, `predn` is an `n`-ary predicate function or functor, where`val1`,
`val2`, ..., and `valn` are its arguments. The assertion succeeds if the
predicate returns `true` when applied to the given arguments, and fails
otherwise. When the assertion fails, it prints the value of each argument. In
either case, the arguments are evaluated exactly once.
Here's an example. Given
```
```c++
// Returns true iff m and n have no common divisors except 1.
boolMutuallyPrime(intm,intn){...}
constinta=3;
constintb=4;
constintc=10;
```
the assertion `EXPECT_PRED2(MutuallyPrime, a, b);` will succeed, while the
assertion `EXPECT_PRED2(MutuallyPrime, b, c);` will fail with the message
the assertion
<pre>
!MutuallyPrime(b, c) is false, where<br>
b is 4<br>
c is 10<br>
</pre>
```c++
EXPECT_PRED2(MutuallyPrime,a,b);
```
**Notes:**
will succeed, while the assertion
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.
1. Currently we only provide predicate assertions of arity <= 5. If you need a higher-arity assertion, let us know.
```c++
EXPECT_PRED2(MutuallyPrime,b,c);
```
_Availability_: Linux, Windows, Mac.
will fail with the message
### Using a Function That Returns an AssertionResult ###
```none
MutuallyPrime(b, c) is false, where
b is 4
c is 10
```
While `EXPECT_PRED*()` and friends are handy for a quick job, the
syntax is not satisfactory: you have to use different macros for
different arities, and it feels more like Lisp than C++. The
`::testing::AssertionResult` class solves this problem.
> NOTE:
>
> 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.
An `AssertionResult` object represents the result of an assertion
(whether it's a success or a failure, and an associated message). You
can create an `AssertionResult` using one of these factory
functions:
**Availability**: Linux, Windows, Mac.
```
#### Using a Function That Returns an AssertionResult
While `EXPECT_PRED*()` and friends are handy for a quick job, the syntax is not
satisfactory: you have to use different macros for different arities, and it
feels more like Lisp than C++. The `::testing::AssertionResult` class solves
this problem.
An `AssertionResult` object represents the result of an assertion (whether it's
a success or a failure, and an associated message). You can create an
`AssertionResult` using one of these factory functions:
```c++
namespacetesting{
// 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_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_EXIT(`_statement, predicate, regex_`);` | `EXPECT_EXIT(`_statement, predicate, regex_`);`|_statement_ exits with the given error and its exit code matches _predicate_ |
`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_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
die, _predicate_ is a function or function object that evaluates an integer
exit status, and _regex_ is a regular expression that the stderr output of
_statement_ is expected to match. Note that _statement_ can be _any valid
statement_ (including _compound statement_) and doesn't have to be an
where `statement` is a statement that is expected to cause the process to die,
`predicate` is a function or function object that evaluates an integer exit
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* (including *compound statement*) and doesn't have to be an
expression.
As usual, the `ASSERT` variants abort the current test function, while the
`EXPECT` variants do not.
**Note:** We use the word "crash" here to mean that the process
terminates with a _non-zero_ exit status code. There are two
possibilities: either the process has called `exit()` or `_exit()`
with a non-zero value, or it may be killed by a signal.
This means that if _statement_ terminates the process with a 0 exit
code, it is _not_ considered a crash by `EXPECT_DEATH`. Use
`EXPECT_EXIT` instead if this is the case, or if you want to restrict
the exit code more precisely.
> NOTE: We use the word "crash" here to mean that the process terminates with a
> *non-zero* exit status code. There are two possibilities: either the process
> has called `exit()` or `_exit()` with a non-zero value, or it may be killed by
> a signal.
>
> This means that if `*statement*` terminates the process with a 0 exit code, it
> is *not* considered a crash by `EXPECT_DEATH`. Use `EXPECT_EXIT` instead if
> this is the case, or if you want to restrict the exit code more precisely.
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:
```
```c++
::testing::ExitedWithCode(exit_code)
```
This expression is `true` if the program exited normally with the given exit
code.
```
```c++
::testing::KilledBySignal(signal_number)// Not available on Windows.
```
...
...
@@ -573,49 +714,63 @@ that verifies the process' exit code is non-zero.
Note that a death test only cares about three things:
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
1. does the stderr output match _regex_?
1. does `statement` abort or exit the process?
2. (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
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
function. For example,
```
```c++
TEST(MyDeathTest,Foo){
// 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).
On Windows, Google Test uses its own simple regular expression
implementation. It lacks many features you can find in POSIX extended
regular expressions. For example, we don't support union (`"x|y"`),
grouping (`"(xy)"`), brackets (`"[xy]"`), and repetition count
(`"x{5,7}"`), among others. Below is what we do support (Letter `A` denotes a
literal character, period (`.`), or a single `\\` escape sequence; `x`
and `y` denote regular expressions.):
| `c` | matches any literal character `c` |
|:----|:----------------------------------|
| `\\d` | matches any decimal digit |
| `\\D` | matches any character that's not a decimal digit |
| `\\f` | matches `\f` |
| `\\n` | matches `\n` |
| `\\r` | matches `\r` |
| `\\s` | matches any ASCII whitespace, including `\n` |
| `\\S` | matches any character that's not a whitespace |
| `\\t` | matches `\t` |
| `\\v` | matches `\v` |
| `\\w` | matches any letter, `_`, or decimal digit |
| `\\W` | matches any character that `\\w` doesn't match |
| `\\c` | matches any literal character `c`, which must be a punctuation |
| `\\.` | matches the `.` character |
| `.` | matches any single character except `\n` |
| `A?` | matches 0 or 1 occurrences of `A` |
| `A*` | matches 0 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 end of a string (not that of each line) |
| `xy` | matches `x` followed by `y` |
To help you determine which capability is available on your system,
Google Test defines macro `GTEST_USES_POSIX_RE=1` when it uses POSIX
extended regular expressions, or `GTEST_USES_SIMPLE_RE=1` when it uses
the simple version. If you want your death tests to work in both
cases, you can either `#if` on these macros or use the more limited
syntax only.
## How It Works ##
Under the hood, `ASSERT_EXIT()` spawns a new process and executes the
death test statement in that process. The details of how precisely
that happens depend on the platform and the variable
`::testing::GTEST_FLAG(death_test_style)` (which is initialized from the
command-line flag `--gtest_death_test_style`).
* On POSIX systems, `fork()` (or `clone()` on Linux) is used to spawn the child, after which:
* If the variable's value is `"fast"`, the death test statement is immediately executed.
* 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.
* 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.
Other values for the variable are illegal and will cause the death test to
fail. Currently, the flag's default value is `"fast"`. However, we reserve the
right to change it in the future. Therefore, your tests should not depend on
this.
In either case, the parent process waits for the child process to complete, and checks that
1. the child's exit status satisfies the predicate, and
1. 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 ##
syntax. To learn about this syntax, you may want to read this
`\\D` | matches any character that's not a decimal digit
`\\f` | matches `\f`
`\\n` | matches `\n`
`\\r` | matches `\r`
`\\s` | matches any ASCII whitespace, including `\n`
`\\S` | matches any character that's not a whitespace
`\\t` | matches `\t`
`\\v` | matches `\v`
`\\w` | matches any letter, `_`, or decimal digit
`\\W` | matches any character that `\\w` doesn't match
`\\c` | matches any literal character `c`, which must be a punctuation
`.` | matches any single character except `\n`
`A?` | matches 0 or 1 occurrences of `A`
`A*` | matches 0 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 end of a string (not that of each line)
`xy` | matches `x` followed by `y`
To help you determine which capability is available on your system, googletest
defines macros to govern which regular expression it is using. The macros are:
<!--absl:google3-begin(google3-only)-->`GTEST_USES_PCRE=1`, or
<!--absl:google3-end-->`GTEST_USES_SIMPLE_RE=1` or `GTEST_USES_POSIX_RE=1`. If
you want your death tests to work in all cases, you can either `#if` on these
macros or use the more limited syntax only.
### How It Works
Under the hood, `ASSERT_EXIT()` spawns a new process and executes the death test
statement in that process. The details of how precisely that happens depend on
the platform and the variable ::testing::GTEST_FLAG(death_test_style) (which is
initialized from the command-line flag `--gtest_death_test_style`).
* On POSIX systems, `fork()` (or `clone()` on Linux) is used to spawn the
child, after which:
* If the variable's value is `"fast"`, the death test statement is
immediately executed.
* 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.
* 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.
Other values for the variable are illegal and will cause the death test to fail.
Currently, the flag's default value is
"fast". However, we reserve
the right to change it in the future. Therefore, your tests should not depend on
this. In either case, the parent process waits for the child process to
complete, and checks that
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
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
may start threads before main is ever reached. Once threads have been created,
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. Test cases with a name ending in "DeathTest" are run before all other tests.
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.
1. A warning is emitted if multiple threads are running when a death test is
encountered.
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
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
risks of testing in a possibly multithreaded environment. It trades increased
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
programmatically:
The automated testing framework does not set the style flag. You can choose a
particular style of death tests by setting the flag programmatically:
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
...
...
@@ -801,7 +970,7 @@ will be undone when the control leaves the current lexical scope.
For example,
```
```c++
10:voidSub1(intn){
11:EXPECT_EQ(1,Bar(n));
12:EXPECT_EQ(2,Bar(n+1));
...
...
@@ -820,7 +989,7 @@ For example,
could result in messages like these:
```
```none
path/to/foo_test.cc:11: Failure
Value of: Bar(n)
Expected: 1
...
...
@@ -834,45 +1003,56 @@ Expected: 2
Actual: 3
```
Without the trace, it would've been difficult to know which invocation
of `Sub1()` the two failures come from respectively. (You could add an
extra message to each assertion in `Sub1()` to indicate the value of
`n`, but that's tedious.)
Without the trace, it would've been difficult to know which invocation of
`Sub1()` the two failures come from respectively. (You could add
an extra message to each assertion in `Sub1()` to indicate the value of `n`, but
that's tedious.)
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. 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.
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 `""`.
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.
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!
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.
2. 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.
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
when they fail they only abort the _current function_, not the entire test. For
example, the following test will segfault:
```
```c++
voidSubroutine(){
// Generates a fatal failure and aborts the current function.
ASSERT_EQ(1,2);
// The following won't be executed.
...
}
TEST(FooTest,Bar){
Subroutine();
// The intended behavior is for the fatal failure
Subroutine();// The intended behavior is for the fatal failure
// in Subroutine() to abort the entire test.
// The actual behavior: the function goes on after Subroutine() returns.
int*p=NULL;
*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
`HasFatalFailure()` function. They are described in the following two
subsections.
...
...
@@ -899,26 +1079,26 @@ int main(int argc, char** argv) {
This listener should be added after other listeners if you have any, otherwise
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_*`
failure in it, the test will continue after the subroutine
returns. This may not be what you want.
As shown above, if your test calls a subroutine that has an `ASSERT_*` failure
in it, the test will continue after the subroutine returns. This may not be what
you want.
Often people want fatal failures to propagate like exceptions. For
that Google Test offers the following macros:
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
determine the result of this type of assertions. If _statement_
creates new threads, failures in these threads are ignored.
Only failures in the thread that executes the assertion are checked to determine
the result of this type of assertions. If `statement` creates new threads,
failures in these threads are ignored.
Examples:
```
```c++
ASSERT_NO_FATAL_FAILURE(Foo());
inti;
...
...
@@ -927,17 +1107,16 @@ EXPECT_NO_FATAL_FAILURE({
});
```
_Availability:_ Linux, Windows, Mac. Assertions from multiple threads
are currently not supported.
**Availability**: Linux, Windows, Mac. Assertions from multiple threads are
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
assertion in the current test has suffered a fatal failure. This
allows functions to catch fatal failures in a sub-routine and return
early.
assertion in the current test has suffered a fatal failure. This allows
functions to catch fatal failures in a sub-routine and return early.
```
```c++
classTest{
public:
...
...
...
@@ -945,15 +1124,15 @@ class Test {
};
```
The typical usage, which basically simulates the behavior of a thrown
exception, is:
The typical usage, which basically simulates the behavior of a thrown exception,
is:
```
```c++
TEST(FooTest,Bar){
Subroutine();
// Aborts if Subroutine() had a fatal failure.
if (HasFatalFailure())
return;
if(HasFatalFailure())return;
// The following won't be executed.
...
}
...
...
@@ -962,25 +1141,24 @@ TEST(FooTest, Bar) {
If `HasFatalFailure()` is used outside of `TEST()` , `TEST_F()` , or a test
fixture, you must add the `::testing::Test::` prefix, as in:
```
if (::testing::Test::HasFatalFailure())
return;
```c++
if(::testing::Test::HasFatalFailure())return;
```
Similarly, `HasNonfatalFailure()` returns `true` if the current test
has at least one non-fatal failure, and `HasFailure()` returns `true`
if the current test has at least one failure of either kind.
Similarly, `HasNonfatalFailure()` returns `true` if the current test has at
least one non-fatal failure, and `HasFailure()` returns `true` if the current
test has at least one failure of either kind.
_Availability:_ Linux, Windows, Mac. `HasNonfatalFailure()` and
`HasFailure()` are available since version 1.4.0.
**Availability**: Linux, Windows, Mac.
# Logging Additional Information #
## Logging Additional Information
In your test code, you can call `RecordProperty("key", value)` to log
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
if you specify one. For example, the test
In your test code, you can call `RecordProperty("key", value)` to log 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](#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
that are expensive to set up, making the one-copy-per-test model prohibitively
expensive.
If the tests don't change the resource, there's no harm in them sharing a
single resource copy. So, in addition to per-test set-up/tear-down, Google Test
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, googletest
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 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.
That's it! Google Test 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.
1. In your test fixture class (say `FooTest` ), declare as `static` some member
variables to hold the shared resources.
1. Outside your test fixture class (typically just below it), define those
member variables, optionally giving them initial values.
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.
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
preceding or following another. Also, the tests must either not modify the
state of any shared resource, or, if they do modify the state, they must
restore the state to its original value before passing control to the next
test.
preceding or following another. Also, the tests must either not modify the state
of any shared resource, or, if they do modify the state, they must restore the
state to its original value before passing control to the next test.
Here's an example of per-test-case set-up and tear-down:
```
```c++
classFooTest:public::testing::Test{
protected:
// Per-test-case set-up.
...
...
@@ -1051,8 +1241,10 @@ class FooTest : public ::testing::Test {
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(){...}
// You can define per-test tear-down logic as usual.
virtualvoidTearDown(){...}
// Some expensive resource shared by all tests.
...
...
@@ -1062,16 +1254,21 @@ class FooTest : public ::testing::Test {
T*FooTest::shared_resource_=NULL;
TEST_F(FooTest,Test1){
... you can refer to shared_resource here ...
...youcanrefertoshared_resource_here...
}
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`.
# Global Set-Up and Tear-Down #
**Availability**: Linux, Windows, Mac.
## Global Set-Up and Tear-Down
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.
...
...
@@ -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
environment, which knows how to set-up and tear-down:
```
```c++
classEnvironment{
public:
virtual~Environment(){}
// Override this to define how to set up the environment.
virtualvoidSetUp(){}
// Override this to define how to tear down the environment.
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:
However, we strongly recommend you to write your own `main()` and call
`AddGlobalTestEnvironment()` there, as relying on initialization of global
variables makes the code harder to read and may cause problems when you
register multiple environments from different translation units and the
environments have dependencies among them (remember that the compiler doesn't
guarantee the order in which global variables from different translation units
are initialized).
_Availability:_ Linux, Windows, Mac.
# Value Parameterized Tests #
_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.
variables makes the code harder to read and may cause problems when you register
multiple environments from different translation units and the environments have
dependencies among them (remember that the compiler doesn't guarantee the order
in which global variables from different translation units are initialized).
## Value-Parameterized Tests
*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`.
```
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*> {
```c++
classFooTest:
public::testing::TestWithParam<constchar*>{
// You can implement all the usual fixture class members here.
// To access the test parameter, call GetParam() from class
// TestWithParam<T>.
...
...
@@ -1193,11 +1371,11 @@ class BarTest : public BaseTest,
};
```
Then, use the `TEST_P` macro to define as many test patterns using
this fixture as you want. The `_P` suffix is for "parameterized" or
"pattern", whichever you prefer to think.
Then, use the `TEST_P` macro to define as many test patterns using this fixture
as you want. The `_P` suffix is for "parameterized" or "pattern", whichever you
prefer to think.
```
```c++
TEST_P(FooTest,DoesBlah){
// 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. |
| `ValuesIn(container)` and | Yields values from a C-style array, an |
: `ValuesIn(begin,end)` : STL-style container, or an iterator range :
: : `[begin, end)`. :
| `Bool()` | Yields sequence `{false, true}`. |
| `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:
*`AnotherInstantiationName/FooTest.DoesBlah/0` for `"cat"`
*`AnotherInstantiationName/FooTest.DoesBlah/1` for `"dog"`
*`AnotherInstantiationName/FooTest.HasBlahBlah/0` for `"cat"`
*`AnotherInstantiationName/FooTest.HasBlahBlah/1` for `"dog"`
*`AnotherInstantiationName/FooTest.DoesBlah/0` for `"cat"`
*`AnotherInstantiationName/FooTest.DoesBlah/1` for `"dog"`
*`AnotherInstantiationName/FooTest.HasBlahBlah/0` for `"cat"`
*`AnotherInstantiationName/FooTest.HasBlahBlah/1` for `"dog"`
Please note that `INSTANTIATE_TEST_CASE_P` will instantiate _all_
tests in the given test case, whether their definitions come before or
_after_ the `INSTANTIATE_TEST_CASE_P` statement.
Please note that `INSTANTIATE_TEST_CASE_P` will instantiate *all* tests in the
given test case, whether their definitions come before or*after* the
`INSTANTIATE_TEST_CASE_P` statement.
You can see
[these](../samples/sample7_unittest.cc)
[files](../samples/sample8_unittest.cc) for more examples.
You can see sample7_unittest.cc and 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
file. Sometimes you may want to define value-parameterized tests in a
library and let other people instantiate them later. This pattern is
known as <i>abstract tests</i>. As an example of its application, when you
are designing an interface you can write a standard suite of abstract
tests (perhaps using a factory function as the test parameter) that
all implementations of the interface are expected to pass. When
someone implements the interface, they can instantiate your suite to get
all the interface-conformance tests for free.
In the above, we define and instantiate `FooTest` in the *same* source file.
Sometimes you may want to define value-parameterized tests in a library and let
other people instantiate them later. This pattern is known as *abstract tests*.
As an example of its application, when you are designing an interface you can
write a standard suite of abstract tests (perhaps using a factory function as
the test parameter) that all implementations of the interface are expected to
pass. When someone implements the interface, they can instantiate your suite to
get all the interface-conformance tests for free.
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 `TEST_P` definitions in `foo_param_test.cc`, which includes `foo_param_test.h`. Think of this as _implementing_ your abstract tests.
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 `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 linking
with`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`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.
# Typed Tests #
### Specifying Names for Value-Parameterized Test Parameters
Suppose you have multiple implementations of the same interface and
want to make sure that all of them satisfy some common requirements.
Or, you may have defined several types that are supposed to conform to
the same "concept" and you want to verify it. In both cases, you want
the same test logic repeated for different types.
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`.
While you can write one `TEST` or `TEST_F` for each type you want to
test (and you may even factor the test logic into a function template
that you invoke from the `TEST`), it's tedious and doesn't scale:
if you want _m_ tests over _n_ types, you'll end up writing _m\*n_
`TEST`s.
`testing::PrintToStringParamName` is a builtin test suffix generator that
returns the value of `testing::PrintToString(GetParam())`. It does not work for
`std::string` or C strings.
_Typed tests_ allow you to repeat the same test logic over a list of
types. You only need to write the test logic once, although you must
know the type list when writing typed tests. Here's how you do it:
NOTE: test names must be non-empty, unique, and may only contain ASCII
alphanumeric characters. In particular, they [should not contain
| `$ foo_test --gtest_repeat=-1` | A negative count means repeating forever. |
| `$ 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. |
@@ -2053,18 +2287,26 @@ could generate this report:
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 `time` attribute expresses the duration of the test, test case, or entire test program in milliseconds.
* Each `<failure>` element corresponds to a single failed Google Test assertion.
* 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 `tests` attribute of a `<testsuites>` or `<testsuite>` element tells how
many test functions the googletest program or test case contains, while the
`failures` attribute tells how many of them failed.
* The `time` attribute expresses the duration of the test, test case, or
entire test program in seconds.
_Availability:_ Linux, Windows, Mac.
* The `timestamp` attribute records the local date and time of the test
execution.
* Each `<failure>` element corresponds to a single failed googletest
assertion.
**Availability**: Linux, Windows, Mac.
#### Generating an JSON Report {#JsonReport}
#### Generating an JSON Report
gUnit can also emit a JSON report as an alternative format to XML. To generate
the JSON report, set the `GUNIT_OUTPUT` environment variable or the
`--gunit_output` flag to the string `"json:path_to_output_file"`, which will
googletest can also emit a JSON report as an alternative format to XML. To
generate the JSON report, set the `GTEST_OUTPUT` environment variable or the
`--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
`"json"`, in which case the output can be found in the `test_detail.json` file
in the current directory.
...
...
@@ -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
@@ -2261,156 +2503,34 @@ IMPORTANT: The exact format of the JSON document is subject to change.
**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
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
other than `0` . Alternatively, you can use the `--gtest_break_on_failure`
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.
### 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:
googletest 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
googletest 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.
```
#include "gtest/gtest.h"
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.
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.
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.
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]`.
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.
1. Wait for all shards to finish, then collect and report the results.
Your project may have tests that were written without Google Test and
thus don't understand this protocol. In order for your test runner to
figure out which test supports sharding, it can set the environment
variable `GTEST_SHARD_STATUS_FILE` to a non-existent file path. If a
test program supports sharding, it will create this file to
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
`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 #
**Availability**: Linux, Windows, Mac.
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
[Primer](primer.md) and [AdvancedGuide](advanced.md), send it to
googletestframework@googlegroups.com.
## Why should test case names and test names not contain underscore?
## 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
which C++ testing framework is **the best**. There exist many fine
frameworks for writing C++ tests, and we have tremendous respect for
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.
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.
We created Google Test because we couldn't find the right combination
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.
User code is *prohibited* from using such identifiers.
Now let's look at what this means for `TEST` and `TEST_F`.
...
...
@@ -64,274 +18,186 @@ Currently `TEST(TestCaseName, TestName)` generates a class named
`TestCaseName_TestName_Test`. What happens if `TestCaseName` or `TestName`
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` 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.
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` 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 `_`
(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 `_`.).
It may seem fine for `TestCaseName` and `TestName` to contain `_` in the middle.
However, consider this:
It may seem fine for `TestCaseName` and `TestName` to contain `_` in the
middle. However, consider this:
```c++
TEST(Time,Flies_Like_An_Arrow){...}
TEST(Time_Flies,Like_An_Arrow){...}
```
Now, the two `TEST`s will both generate the same class
(`Time_Files_Like_An_Arrow_Test`). That's not good.
So for simplicity, we just ask the users to avoid `_` in `TestCaseName`
and `TestName`. The rule is more constraining than necessary, but it's
simple and easy to remember. It also gives Google Test some wiggle
room in case its implementation needs to change in the future.
If you violate the rule, there may not be immediately consequences,
but your test may (just may) break with a new compiler (or a new
version of the compiler you are using) or with a new version of Google
Test. Therefore it's best to follow the rule.
## Why is it not recommended to install a pre-compiled copy of Google Test (for example, into /usr/local)? ##
In the early days, we said that you could install
compiled Google Test libraries on `*`nix systems using `make install`.
Then every user of your machine can write tests without
recompiling Google Test.
This seemed like a good idea, but it has a
got-cha: every user needs to compile their tests using the _same_ compiler
flags used to compile the installed Google Test libraries; otherwise
they may run into undefined behaviors (i.e. the tests can behave
strangely and may even crash for no obvious reasons).
Why? Because C++ has this thing called the One-Definition Rule: if
two C++ source files contain different definitions of the same
class/function/variable, and you link them together, you violate the
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
doesn't, you get strange run-time behaviors that are unexpected and
hard to debug.
If you compile Google Test and your test code using different compiler
flags, they may see different definitions of the same
class/function/variable (e.g. due to the use of `#if` in Google Test).
Therefore, for your sanity, we recommend to avoid installing pre-compiled
Google Test libraries. Instead, each project should compile
Google Test itself such that it can be sure that the same flags are
used for both Google Test and the tests.
## How do I generate 64-bit binaries on Windows (using Visual Studio 2008)? ##
(Answered by Trevor Robinson)
Load the supplied Visual Studio solution file, either `msvc\gtest-md.sln` or
`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
(`Time_Flies_Like_An_Arrow_Test`). That's not good.
So for simplicity, we just ask the users to avoid `_` in `TestCaseName` and
`TestName`. The rule is more constraining than necessary, but it's simple and
easy to remember. It also gives googletest some wiggle room in case its
implementation needs to change in the future.
If you violate the rule, there may not be immediate consequences, but your test
may (just may) break with a new compiler (or a new version of the compiler you
are using) or with a new version of googletest. Therefore it's best to follow
the rule.
## Why does googletest support `EXPECT_EQ(NULL, ptr)` and `ASSERT_EQ(NULL, ptr)` but not `EXPECT_NE(NULL, ptr)` and `ASSERT_NE(NULL, ptr)`?
First of all you can use `EXPECT_NE(nullptr, ptr)` and `ASSERT_NE(nullptr,
ptr)`. This is the preferred syntax in the style guide because nullptr does not
have the type problems that NULL does. Which is why NULL does not work.
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 googletest 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 the gMock matcher 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.
## Does Google Test support running tests in parallel? ##
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.
## I need to test that different implementations of an interface satisfy some common requirements. Should I use typed tests or value-parameterized tests?
## 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
with thread-safety in mind, and thus may not work correctly in a
multi-threaded setting.
* Typed tests can be easier to write if instances of the different
implementations can be created the same way, modulo the type. For example,
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
you know what other threads are doing. It's much harder, and
sometimes even impossible, to make your code work when you don't know
what other threads are doing (remember that test methods can be added,
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.
I hope I didn't confuse you more. :-) If you don't mind, I'd suggest you to give
both approaches a try. Practice is a much better way to grasp the subtle
differences between the two tools. Once you have some concrete experience, you
can much more easily decide which one to use the next time.
## 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
that disable exceptions. Later we realized some additional benefits
of this approach:
In August 2008 we had to switch the default death test style from `fast` to
`threadsafe`, as the former is no longer safe now that threaded logging is the
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.
Please read [Fixing Failing Death Tests](death_test_styles.md) for what you can
do.
The downside of not using exceptions is that `ASSERT_*` (implemented
using `return`) will only abort the current function, not the current
`TEST`.
## I got some run-time errors about invalid proto descriptors when using `ProtocolMessageEquals`. Help!
## Why do we use two different macros for tests with and without fixtures? ##
**Note:**`ProtocolMessageEquals` and `ProtocolMessageEquiv` are *deprecated*
now. Please use `EqualsProto`, etc instead.
Unfortunately, C++'s macro system doesn't allow us to use the same
macro for both cases. One possibility is to provide only one macro
for tests with fixtures, and require the user to define an empty
fixture sometimes:
`ProtocolMessageEquals` and `ProtocolMessageEquiv` were redefined recently and
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:
```c++
classFooTest:public::testing::Test{};
TEST_F(FooTest,DoesThis){...}
```
or
```c++
typedef::testing::TestFooTest;
TEST_F(FooTest,DoesThat){...}
... descriptor.cc:...] Invalid proto descriptor for file "path/to/foo.proto":
... descriptor.cc:...] blah.MyMessage.my_field: ".Bar" is not defined.
```
Yet, many people think this is one line toomany. :-) Our goal was to
make it really easy to write tests, so we tried to make simple tests
trivial to create. That means using a separate macro for such tests.
If you see this, your `.proto` file is broken and needs to be fixed by making
the types fully qualified. The new definition of `ProtocolMessageEquals` and
`ProtocolMessageEquiv` just happen to reveal your bug.
We think neither approach is ideal, yet either of them is reasonable.
In the end, it probably doesn't matter much either way.
## My death test modifies some state, but the change seems lost after the death test finishes. Why?
## 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
distinction between structs and classes is good for documenting the
intent of the code's author. Since test fixtures have logic like
`SetUp()` and `TearDown()`, they are better defined as classes.
In particular, if you use [gMock](http://go/gmock) and the death test statement
invokes some mock methods, the parent process will think the calls have never
occurred. Therefore, you may want to move your `EXPECT_CALL` statements inside
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++
possibly allows. In particular:
Actually, the bug is in `htonl()`.
* 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.
*`ASSERT_DEATH` has a similar syntax and error-reporting semantics as other Google Test assertions, and thus is easy to learn.
*`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:
```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.
According to `'man htonl'`, `htonl()` is a *function*, which means it's valid to
use `htonl` as a function pointer. However, in opt mode `htonl()` is defined as
a *macro*, which breaks this usage.
Another interesting thing about `ASSERT_DEATH` is that it calls `fork()`
to create a child process to run the death test. This is lightening
fast, as `fork()` uses copy-on-write pages and incurs almost zero
overhead, and the child process starts from the user-supplied
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.
Worse, the macro definition of `htonl()` uses a `gcc` extension and is *not*
standard C++. That hacky implementation has some ad hoc limitations. In
particular, it prevents you from writing `Foo<sizeof(htonl(x))>()`, where `Foo`
is a template that has an integral argument.
## 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
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.
`htonl()` has some other problems as described in `//util/endian/endian.h`,
which defines `ghtonl()` to replace it. `ghtonl()` does the same thing `htonl()`
does, only without its problems. We suggest you to use `ghtonl()` instead of
`htonl()`, both in your tests and production code.
`//util/endian/endian.h` also defines `ghtons()`, which solves similar problems
in `htons()`.
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? ##
## 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:
...
...
@@ -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++
constintFoo::kBar;// No initializer here.
```
Otherwise your code is **invalid C++**, and may break in unexpected ways. In
particular, using it in Google Test comparison assertions (`EXPECT_EQ`, etc)
will generate an "undefined reference" linker error.
## 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.
particular, using it in googletest comparison assertions (`EXPECT_EQ`, etc) will
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. :-)
## Can I derive a test fixture from another? ##
## Can I derive a test fixture from another?
Yes.
...
...
@@ -369,10 +230,10 @@ 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
important system resources like fonts and brushes.
In Google Test, you share a fixture among test cases by putting the shared
logic in a base test fixture, then deriving from that base a separate fixture
for each test case that wants to use this common logic. You then use `TEST_F()`
to write tests using each derived fixture.
In googletest, you share a fixture among test cases by putting the shared logic
in a base test fixture, then deriving from that base a separate fixture for each
test case that wants to use this common logic. You then use `TEST_F()` to write
tests using each derived fixture.
Typically, your code looks like this:
...
...
@@ -386,15 +247,17 @@ class BaseTest : public ::testing::Test {
// Derives a fixture FooTest from BaseTest.
classFooTest:publicBaseTest{
protected:
virtualvoidSetUp(){
voidSetUp()override{
BaseTest::SetUp();// Sets up the base fixture first.
...additionalset-upwork...
}
virtualvoidTearDown(){
voidTearDown()override{
...clean-upworkforFooTest...
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`.
`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.
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
process. So the first thing you can try is to eliminate creating threads
outside of `EXPECT_DEATH()`.
process. So the first thing you can try is to eliminate creating threads outside
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
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
`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
test style to `"threadsafe"`, which is safer but slower, and see if it helps.
leaving as few things as possible in it. Also, you can try to set the death test
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
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
sure that there is no race conditions or dead locks in your program. No silver
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
same test fixture object across multiple tests. For each `TEST_F`,
Google Test will create a fresh test fixture object, _immediately_
call `SetUp()`, run the test body, call `TearDown()`, and then
_immediately_ delete the test fixture object.
The first thing to remember is that googletest does **not** reuse the same test
fixture object across multiple tests. For each `TEST_F`, googletest will create
a **fresh** test fixture object, immediately call `SetUp()`, run the test body,
call `TearDown()`, and then delete the test fixture object.
When you need to write per-test set-up and tear-down logic, you have
the choice between using the test fixture constructor/destructor or
`SetUp()/TearDown()`. The former is usually preferred, as it has the
following benefits:
When you need to write per-test set-up and tear-down logic, you have the choice
between using the test fixture constructor/destructor or `SetUp()/TearDown()`.
The former is usually preferred, as it has the 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.
* 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.
* 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.
* 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:
* 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
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
type of the function pointer for the `int`-version of `IsPositive()`.)
(The stuff inside the angled brackets for the `static_cast` operator is the type
of the function pointer for the `int`-version of `IsPositive()`.)
As another example, when you have a template function
...
...
@@ -522,72 +413,76 @@ following won't compile:
ASSERT_PRED2(GreaterThan<int,int>,5,0);
```
as the C++ pre-processor thinks you are giving `ASSERT_PRED2` 4 arguments,
which is one more than expected. The workaround is to wrap the predicate
function in parentheses:
as the C++ pre-processor thinks you are giving `ASSERT_PRED2` 4 arguments, which
is one more than expected. The workaround is to wrap the predicate function in
parentheses:
```c++
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,
instead of
```c++
returnRUN_ALL_TESTS();
returnRUN_ALL_TESTS();
```
they write
```c++
RUN_ALL_TESTS();
RUN_ALL_TESTS();
```
This is wrong and dangerous. A test runner needs to see the return value of
`RUN_ALL_TESTS()` in order to determine if a test has passed. If your`main()`
function ignores it, your test will be considered successful even if it has a
Google Test assertion failure. Very bad.
This is **wrong and dangerous**. The testing services needs to see the return
value of `RUN_ALL_TESTS()` in order to determine if a test has passed. If your
`main()`function ignores it, your test will be considered successful even if it
has a googletest assertion failure. Very bad.
To help the users avoid this dangerous bug, the implementation of
`RUN_ALL_TESTS()` causes gcc to raise this warning, when the return value is
ignored. If you see this warning, the fix is simple: just make sure its value
is used as the return value of `main()`.
We have decided to fix this (thanks to Michael Chastain for the idea). Now, your
code will no longer be able to ignore `RUN_ALL_TESTS()` when compiled with
`gcc`. If you do so, you'll get a compiler error.
## 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
messages to an `ASSERT_*`, e.g.
```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
`ADD_FAILURE*`) in constructors and destructors. The workaround is to move the
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
it.
switch to `EXPECT_*()` if that works. This
[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
spell it as `Setup()`?
C++ is case-sensitive. Did you spell it as `Setup()`?
Similarly, sometimes people spell `SetUpTestCase()` as `SetupTestCase()` and
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
your test generates textual output itself, it will mix with the Google Test
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 googletest
output, making it hard to read. However, there is an easy solution to this
problem.
Since most log messages go to stderr, we decided to let Google Test output go
to stdout. This way, you can easily separate the two using redirection. For
Since `LOG` messages go to stderr, we decided to let googletest output go to
stdout. This way, you can easily separate the two using redirection. For
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
tested from their public interface. One way to achieve this is the Pimpl idiom:
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();
}
```shell
$ ./my_test > gtest_output.txt
```
* 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) {
...
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
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:
## I have a fixture class Foo, but TEST\_F(Foo, Bar) gives me error "no matching function for call to Foo::Foo()". Why? ##
* If you explicitly declare a non-default constructor for class `FooTest`
(`DISALLOW_EVIL_CONSTRUCTORS()` does this), 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
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`.)
Google Test 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:
* 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 `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`.)
## 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
line from single thread to multiple threads. The first time you create a
thread, a manager thread is created in addition, so you get 3, not 2, threads.
Later when the thread you create joins the main thread, the thread count
decrements by 1, but the manager thread will never be killed, so you still have
2 threads, which means you cannot safely run a death test.
With the Linux pthread library, there is no turning back once you cross the line
from single thread to multiple threads. The first time you create a thread, a
manager thread is created in addition, so you get 3, not 2, threads. Later when
the thread you create joins the main thread, the thread count decrements by 1,
but the manager thread will never be killed, so you still have 2 threads, which
means you cannot safely run a death test.
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
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
runs all tests in one test case first, and then runs all tests in the next test
case, and so on. Google Test does this because it needs to set up a test case
before the first test in it is run, and tear it down afterwords. Splitting up
the test case would require multiple set-up and tear-down processes, which is
inefficient and makes the semantics unclean.
googletest does not interleave tests from different test cases. That is, it runs
all tests in one test case first, and then runs all tests in the next test case,
and so on. googletest does this because it needs to set up a test case before
the first test in it is run, and tear it down afterwords. Splitting up the test
case would require multiple set-up and tear-down processes, which is inefficient
and makes the semantics unclean.
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:
...
...
@@ -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
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
`FooTest` and `FooDeathTest`, where the names make it clear that they are
...
...
@@ -909,119 +658,81 @@ class FooTest : public ::testing::Test { ... };
TEST_F(FooTest,Abc){...}
TEST_F(FooTest,Def){...}
typedef FooTest FooDeathTest;
usingFooDeathTest=FooTest;
TEST_F(FooDeathTest,Uvw){...EXPECT_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
there is an `std::ostream& operator<<(std::ostream&, const FooType&)` function
defined such that we can print a value of `FooType`.
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
end of the program run. The easiest way to avoid this is to use the
`_CrtMemCheckpoint` and `_CrtMemDumpAllObjectsSince` calls to not report any
statically initialized heap objects. See MSDN for more details and additional
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.
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.
