Fix tests utils to make --directory work correctly.

[robinwnv]

Currently, when cwd is not cunumeric dir where test.py is located, if we use default root_dir or specify the directory, no test files would be found and zero division error is reported in summary.

In this change, we do two enhancements:

1. In test_files method in config.py, use absolute path of test file which includes root_dir
2. Fix total=0 in summary to avoid zero division error

[bryevdv]

@robinw0928 Your changes have broken the handling of SKIPPED_EXAMPLES:

cunumeric/tests/_utils/__init__.py

Lines 64 to 69 in bf3e6da

	SKIPPED_EXAMPLES = {
	"examples/ingest.py",
	"examples/kmeans_sort.py",
	"examples/lstm_full.py",
	"examples/wgrad.py",
	}

There are four failing tests, exactly these four, that should not be run at all. You will need to update your changes to make sure that the SKIPPED_EXAMPLES set is still respected. The current handling is here, and you can see why it no longer works since the paths are absolute now:

cunumeric/tests/_utils/config.py

Lines 103 to 107 in bf3e6da

	examples = (
	path
	for path in Path("examples").glob("*.py")
	if str(path) not in SKIPPED_EXAMPLES
	)

Also, FYI I wrote tests for the test driver itself:

bldtest ❯ pytest tests/_utils/tests
================================ test session starts =================================
platform linux -- Python 3.9.13, pytest-7.1.2, pluggy-1.0.0
rootdir: /home/bryan/build_test/cunumeric, configfile: pyproject.toml
plugins: mock-3.8.2, cov-3.0.0, lazy-fixture-0.6.3
collected 153 items                                                                  

tests/_utils/tests/test___init__.py ...........                                [  7%]
tests/_utils/tests/test_args.py ........................                       [ 22%]
tests/_utils/tests/test_config.py ................................             [ 43%]
tests/_utils/tests/test_logger.py ........                                     [ 49%]
tests/_utils/tests/test_system.py .....                                        [ 52%]
tests/_utils/tests/test_types.py ..                                            [ 53%]
tests/_utils/tests/test_ui.py .............                                    [ 62%]
tests/_utils/tests/stages/test_test_stage.py ......                            [ 66%]
tests/_utils/tests/stages/test_util.py ..........                              [ 72%]
tests/_utils/tests/stages/_linux/test_cpu.py ............                      [ 80%]
tests/_utils/tests/stages/_linux/test_eager.py .......                         [ 84%]
tests/_utils/tests/stages/_linux/test_gpu.py .........                         [ 90%]
tests/_utils/tests/stages/_linux/test_omp.py ..............                    [100%]

================================ 153 passed in 1.49s =================================

They aren't yet run in CI. I plan to figure out how to add them to CI when the test driver code moves down to legate-core. I would appreciate if you try to make sure these test-driver tests are also updated for any changes you make. They can be run manually at the top level of cunumeric with pytest tests/_utils/tests

[robinwnv]

Thanks @bryevdv
I choose to use relative path in test_file. In this way, we can support specifying --files using relative path.
"They can be run manually at the top level of cunumeric with pytest tests/_utils/tests" I have verified on my local machine. It pass.

[bryevdv]

@robinw0928 can you look in to installing the pre-commit hooks for this repo, so that the black formatting happens automatically? Alternatively, you can run black and isort manually before pushing, ot avoid all the pre-commit autofix noise in PRs.

[bryevdv]

@robinw0928 The now unused PurePath import needs to be removed. This is another good reason to make sure the pre-commit hooks are installed, this would have been caught locally, before you could push changes:

tests/_utils/config.py:22:1: F401 'pathlib.PurePath' imported but unused