[RFC PATCH 0/2] add an external testing library for unit tests

In our current testing environment, we spend a significant amount of effort crafting end-to-end tests for error conditions that could easily be captured by unit tests (or we simply forgo some hard-to-setup and rare error conditions). Unit tests additionally provide stability to the codebase and can simplify debugging through isolation. Turning parts of Git into libraries[1] gives us the ability to run unit tests on the libraries and to write unit tests in C. Writing unit tests in pure C, rather than with our current shell/test-tool helper setup, simplifies test setup, simplifies passing data around (no shell-isms required), and reduces testing runtime by not spawning a separate process for every test invocation.

Unit testing in C requires a separate testing harness that we ideally would like to be TAP-style and to come with a non-restrictive license. Fortunately, there already exists a C TAP harness library[2] with an MIT license (at least for the files included in this series).

This first patch introduces the C TAP harness and includes only the necessary files. The second patch showcases a basic example of it. As an RFC, I am wondering what the list thinks about using a second testing library for unit testing? Are there any problems with this particular external testing library and does it provide the necessary functionality we would want for unit testing Git libraries? How should the folders be structured and how should the new Makefile rules be written? Ultimately, this will help us determine the setup of our unit tests in future libification patches.

[1] https://lore.kernel.org/git/CAJoAoZ=Cig_kLocxKGax31sU7Xe4==BGzC__Bg2_pr7krNq6MA@mail.gmail.com/ [2] https://github.com/rra/c-tap-harness/

Calvin Wan (2):
  Add C TAP harness
  unit test: add basic example

 Makefile       |   11 +
 t/TESTS        |    1 +
 t/runtests.c   | 1789 ++++++++++++++++++++++++++++++++++++++++++++++++
 t/tap/basic.c  | 1029 ++++++++++++++++++++++++++++
 t/tap/basic.h  |  198 ++++++
 t/tap/macros.h |  109 +++
 t/unit-test.c  |   14 +
 7 files changed, 3151 insertions(+)
 create mode 100644 t/TESTS
 create mode 100644 t/runtests.c
 create mode 100644 t/tap/basic.c
 create mode 100644 t/tap/basic.h
 create mode 100644 t/tap/macros.h
 create mode 100644 t/unit-test.c