See discussion here:
https://github.com/llvm/llvm-project/issues/55982
We don't generally expect test files to be formatted according to the
style guide. Indeed, some tests may require specific formatting for the
purposes of the test.
When tests intentionally do not conform to the "correct" formatting,
this causes errors in the CI, which can drown out real errors and causes
people to stop trusting the CI over time.
From the history of the clang/test/.clang-format file, it looks as if
there have been attempts to make clang-format do a subset of formatting
that would be useful for tests. However, it looks as if it's hard to
make clang-format do exactly the right thing -- see the back-and-forth
between
13316a7
and
7b5bddf.
Instead, I think the best choice is to entirely disable clang-format on
the clang/test directory.