I find some aspects of the way that `PhutilUnitTestEngine` works to be counter-intuitive (this might extend to other `ArcanistUnitTestEngine` subclasses as well). Specifically, it is not possible to execute a single test path. I would expect that `arc unit -- src/lint/linter/__tests__/ArcanistChmodLinterTestCase.php` would execute only the tests in the `ArcanistChmodLinterTestCase` class, but instead it executes all tests in the `src/lint/linter/__tests__/` directory. This can be annoying when writing new tests (especially tests for linters) because it slows down the ability of running the tests.