Writing Clar tests for libgit2

For information on the Clar testing framework and a detailed introduction please visit:

https://github.com/vmg/clar

• Write your modules and tests. Use good, meaningful names.

• Make sure you actually build the tests by setting:

    cmake -DBUILD_CLAR=ON build/
  

• Test:

    ./build/libgit2_clar
  

• Make sure everything is fine.

• Send your pull request. That's it.

Memory leak checks

These are automatically run as part of CI, but if you want to check locally:

Linux

Uses valgrind:

$ cmake -DBUILD_CLAR=ON -DVALGRIND=ON ..
$ cmake --build .
$ valgrind --leak-check=full --show-reachable=yes --num-callers=50 --suppressions=../libgit2_clar.supp \
  ./libgit2_clar

macOS

Uses leaks, which requires XCode installed:

$ MallocStackLogging=1 MallocScribble=1 MallocLogFile=/dev/null CLAR_AT_EXIT="leaks -quiet \$PPID" \
  ./libgit2_clar