1<a id="top"></a>
2# Contributing to Catch
3
4So you want to contribute something to Catch? That's great! Whether it's a bug fix, a new feature, support for
5additional compilers - or just a fix to the documentation - all contributions are very welcome and very much appreciated.
6Of course so are bug reports and other comments and questions.
7
8If you are contributing to the code base there are a few simple guidelines to keep in mind. This also includes notes to
9help you find your way around. As this is liable to drift out of date please raise an issue or, better still, a pull
10request for this file, if you notice that.
11
12## Branches
13
14Ongoing development is currently on _master_. At some point an integration branch will be set-up and PRs should target
15 that - but for now it's all against master. You may see feature branches come and go from time to time, too.
16
17## Directory structure
18
19_Users_ of Catch primarily use the single header version. _Maintainers_ should work with the full source (which is still,
20primarily, in headers). This can be found in the `include` folder. There are a set of test files, currently under
21`projects/SelfTest`. The test app can be built via CMake from the `CMakeLists.txt` file in the root, or you can generate
22project files for Visual Studio, XCode, and others (instructions in the `projects` folder). If you have access to CLion,
23it can work with the CMake file directly.
24
25As well as the runtime test files you'll also see a `SurrogateCpps` directory under `projects/SelfTest`.
26This contains a set of .cpp files that each `#include` a single header.
27While these files are not essential to compilation they help to keep the implementation headers self-contained.
28At time of writing this set is not complete but has reasonable coverage.
29If you add additional headers please try to remember to add a surrogate cpp for it.
30
31The other directories are `scripts` which contains a set of python scripts to help in testing Catch as well as
32generating the single include, and `docs`, which contains the documentation as a set of markdown files.
33
34__When submitting a pull request please do not include changes to the single include, or to the version number file
35as these are managed by the scripts!__
36
37
38## Testing your changes
39
40Obviously all changes to Catch's code should be tested. If you added new
41functionality, you should add tests covering and showcasing it. Even if you have
42only made changes to Catch internals (i.e. you implemented some performance
43improvements), you should still test your changes.
44
45This means 2 things
46
47* Compiling Catch's SelfTest project:
48```
49$ cd Catch2
50$ cmake -Bdebug-build -H. -DCMAKE_BUILD_TYPE=Debug
51$ cmake --build debug-build
52```
53because code that does not compile is evidently incorrect. Obviously,
54you are not expected to have access to all the compilers and platforms
55supported by Catch2, but you should at least smoke test your changes
56on your platform. Our CI pipeline will check your PR against most of
57the supported platforms, but it takes an hour to finish -- compiling
58locally takes just a few minutes.
59
60
61* Running the tests via CTest:
62```
63$ cd debug-build
64$ ctest -j 2 --output-on-failure
65```
66If you added new tests, approval tests are very likely to fail. If they
67do not, it means that your changes weren't run as part of them. This
68_might_ be intentional, but usually is not.
69
70The approval tests compare current output of the SelfTest binary in various
71configurations against known good outputs. The reason it fails is,
72_usually_, that you've added new tests but have not yet approved the changes
73they introduce. This is done with the `scripts/approve.py` script, but
74before you do so, you need to check that the introduced changes are indeed
75intentional.
76
77
78
79 *this document is still in-progress...*
80
81---
82
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