Use lru_cache clear fixture at test module level

src/darker/tests/conftest.py

@@ -129,6 +129,10 @@ def git_repo(tmp_path, monkeypatch):
 def find_project_root_cache_clear():
     """Clear LRU caching in :func:`black.find_project_root` before each test
 
+    To use this on all test cases in a test module, add this to the top::
+
+        pytestmark = pytest.mark.usefixtures("find_project_root_cache_clear")
+
     NOTE: We use `darker.black_compat.find_project_root` to wrap Black's original
     function since its signature has changed along the way. However, clearing the cache
     needs to be done on the original of course.

src/darker/tests/test_config.py

@@ -23,6 +23,8 @@
 )
 from darker.tests.helpers import raises_if_exception
 
+pytestmark = pytest.mark.usefixtures("find_project_root_cache_clear")
+
 
 @pytest.mark.kwparametrize(
     dict(list_value=[], expect="[\n]"),
@@ -376,7 +378,7 @@ def test_output_mode_from_args(diff, stdout, expect):
     expect={"CONFIG_PATH": "."},
 )
 def test_load_config(  # pylint: disable=too-many-arguments
-    find_project_root_cache_clear, tmp_path, monkeypatch, srcs, cwd, confpath, expect
+    tmp_path, monkeypatch, srcs, cwd, confpath, expect
 ):
     """``load_config()`` finds and loads configuration based on source file paths"""
     (tmp_path / ".git").mkdir()

src/darker/tests/test_import_sorting.py

@@ -16,6 +16,8 @@
 ORIGINAL_SOURCE = ("import sys", "import os", "", "print(42)")
 ISORTED_SOURCE = ("import os", "import sys", "", "print(42)")
 
+pytestmark = pytest.mark.usefixtures("find_project_root_cache_clear")
+
 
 @pytest.mark.parametrize("present", [True, False])
 def test_import_sorting_importable_with_and_without_isort(present):
@@ -132,14 +134,7 @@ def test_apply_isort_exclude(git_repo, encoding, newline, content, exclude, expe
         ),
     ),
 )
-def test_isort_config(
-    monkeypatch,
-    tmpdir,
-    find_project_root_cache_clear,
-    line_length,
-    settings_file,
-    expect,
-):
+def test_isort_config(monkeypatch, tmpdir, line_length, settings_file, expect):
     """``apply_isort()`` parses ``pyproject.toml``correctly"""
     monkeypatch.chdir(tmpdir)
     (tmpdir / "pyproject.toml").write(

src/darker/tests/test_main.py

@@ -25,6 +25,8 @@
 from darker.utils import TextDocument, joinlines
 from darker.verification import NotEquivalentError
 
+pytestmark = pytest.mark.usefixtures("find_project_root_cache_clear")
+
 
 def _replace_diff_timestamps(text, replacement="<timestamp>"):
     return re.sub(r"\d{4}-\d\d-\d\d \d\d:\d\d:\d\d\.\d\d\d\d\d\d", replacement, text)
@@ -45,7 +47,7 @@ def test_isort_option_without_isort(git_repo, caplog):
 
 
 @pytest.fixture
-def run_isort(git_repo, monkeypatch, caplog, request, find_project_root_cache_clear):
+def run_isort(git_repo, monkeypatch, caplog, request):
     """Fixture for running Darker with requested arguments and a patched `isort`
 
     Provides an `run_isort.isort_code` mock object which allows checking whether and how
@@ -470,7 +472,6 @@ def test_main(
     git_repo,
     monkeypatch,
     capsys,
-    find_project_root_cache_clear,
     arguments,
     newline,
     pyproject_toml,
@@ -573,9 +574,7 @@ def test_main_in_plain_directory(tmp_path, capsys):
     "encoding, text", [(b"utf-8", b"touch\xc3\xa9"), (b"iso-8859-1", b"touch\xe9")]
 )
 @pytest.mark.parametrize("newline", [b"\n", b"\r\n"])
-def test_main_encoding(
-    git_repo, find_project_root_cache_clear, encoding, text, newline
-):
+def test_main_encoding(git_repo, encoding, text, newline):
     """Encoding and newline of the file is kept unchanged after reformatting"""
     paths = git_repo.add({"a.py": newline.decode("ascii")}, commit="Initial commit")
     edited = [b"# coding: ", encoding, newline, b's="', text, b'"', newline]