GitLab

https://github.com/sphinx-doc/sphinx/issues/3212

A flake8 configuration is included in setup.cfg and the checks are
executed automatically on Travis:

* Ensures a consistent PEP8 code style
* Does basic linting to prevent possible bugs

- Try to update and upgrade twice (with a brief pause between attempts)
  to deal with occassional spurious server failures or repository race
  conditions.  Do the same for the main package install.
- Use dist-upgrade instead of upgrade for updating the image
- Add -q to the upgrade and install commands to make apt less verbose.

This adds a tool that checks style (currently just for tabs instead of
spaces in files under include/tests/docs) and produces a travis-ci build
failure if any problems are found.

Installing something outside the project directory from a cmake
invocation is overly intrusive; this changes tests/CMakeLists.txt to
just fail with an informative message instead, and changes the
travis-ci builds to install pytest via pip or apt-get.

ccache on Travis was never configured properly so the setting never
actually did anything. Enabling ccache for real brings other issues:
due to the way the preprocessor is handled, some of the Python header
macros produce bogus compiler warnings (which in turn produce errors
with -Werror). ccache also requires additional configuration on OS X
and docker. It would reduce compile time by ~30 seconds at best, so
it's not worth the trouble.

[skip appveyor]

This build makes sure everything still works without optional
dependencies (numpy/scipy/eigen) and also tests the automatic
discovery functions in CMake (Python version, C++ standard).

[skip appveyor]

Pytest is a development dependency but we can make it painless by
automating the install using CMake.

Use simple asserts and pytest's powerful introspection to make testing
simpler. This merges the old .py/.ref file pairs into simple .py files
where the expected values are right next to the code being tested.

This commit does not touch the C++ part of the code and replicates the
Python tests exactly like the old .ref-file-based approach.

Rather than adding an `if [ -n "$DOCS" ]` as a separate install
instruction, this simplifies the travis-ci logic to do the pip/venv
setup in the `before_install` hook, leaving the install hook to just
install the needed packages.

This makes the default install script simpler: it doesn't need to check
NATIVE_DEPS or DOCS because both of those now override `install`
anyway, so the top-level `install` is really just the install for the
gcc-4.8 and osx builds; the docker builds and docs build override
install completely.

This switches the travis-ci build to build the docs in a dedicated
build rather than as part of the regular linux/osx builds.

The current linux/g++ testing (using a backported g++-4.8 on a
4-year-old Ubuntu) is quite ancient.  It's good as a baseline level of
support, but it means we aren't testing g++'s C++14 support at all
(which is why #334 happened).

This commit adds a docker-based travis-ci build using the debian
"testing" distribution, which will give us both another test system
(with different versions of build tools), while, more importantly, also
adding a build and test run using g++ in C++14 mode.