def METHOD_NAME(self) -> None:
    self.make_file("bar.py")
    self.make_file("pkg/sub_package/__init__.py")
    self.make_file("pkg/sub_package/foo.py")
    # Run twice to test both cached and non-cached code paths.
    for i in range(2):
        assert self.isfile_case("bar.py")
        assert self.isfile_case("pkg/sub_package/__init__.py")
        assert self.isfile_case("pkg/sub_package/foo.py")
        assert not self.isfile_case("non_existent.py")
        assert not self.isfile_case("pkg/non_existent.py")
        assert not self.isfile_case("pkg/")
        assert not self.isfile_case("bar.py/")
    for i in range(2):
        assert not self.isfile_case("Bar.py")
        assert not self.isfile_case("pkg/sub_package/__init__.PY")
        assert not self.isfile_case("pkg/Sub_Package/foo.py")
        assert not self.isfile_case("Pkg/sub_package/foo.py")