[libcxx-commits] [libcxx] Update testing documentation with testing guidelines. (PR #87928)

[Louis Dionne via libcxx-commits]

================
@@ -180,6 +180,42 @@ The tests of libc++ are stored in libc++'s testing related subdirectories:
   ``libcxx/test/libcxx``. The structure of this directories follows the
   structure of ``libcxx/test/std``.
 
+Principles of testing
----------------
ldionne wrote:

I think I might move this before the "structure of the testing related directories" since it's more general?

https://github.com/llvm/llvm-project/pull/87928