This library is free, and will stay free but needs your support to sustain its development. There are lots of new features and maintenance to do. If you work for a company using doctest or have the means to do so, please consider financial support.
Consider opening an issue for a discussion before making a pull request to make sure the contribution goes smoothly.
All pull requests should be made against the dev branch because the master is the stable one with the latest release.
If you're going to change something in the library itself - make sure you don't modify doctest/doctest.h because it's generated from doctest/parts/doctest_fwd.h and doctest/parts/doctest_impl.h - they get concatenated by CMake - so make sure you do a CMake build after you modify them so the assemble_single_header target gets built. Also take into consideration how the change affects the code coverage - based on the project in examples/all_features. Also update any relevant examples in the examples folder.
This framework has some design goals which must be kept. Make sure you have read the features and design goals page.
If your changes also change the output of the library - you should also update the reference output for the tests or otherwise the CI builds (travis and appveyor) will fail when they compare the latest output to the outdated reference output (which is committed in the repository). To do this run CMake with the DOCTEST_TEST_MODE variable set to COLLECT (making the new reference output) and then run ctest and commit the changed (or newly created) .txt files in the test_output folders too. The default DOCTEST_TEST_MODE is COMPARE.
Example: cmake -DDOCTEST_TEST_MODE=COLLECT path/to/sources && cmake --build . && ctest
Code should be formatted with a recent-enough clang-format using the config file in the root of the repo (or I will do it...)
Testing with compilers different from GCC/Clang/MSVC (and more platforms) is something the project would benefit from.