Add unit tests for LintModuleOutputUpdate

tests/testutils/test_lint_module_output_update.py

@@ -0,0 +1,63 @@
+# Licensed under the GPL: https://www.gnu.org/licenses/old-licenses/gpl-2.0.html
+# For details: https://github.com/PyCQA/pylint/blob/main/LICENSE
+
+# pylint: disable=redefined-outer-name
+from pathlib import Path
+from typing import Callable, Tuple
+
+import pytest
+
+from pylint.testutils import FunctionalTestFile
+from pylint.testutils.functional import LintModuleOutputUpdate
+
+
+@pytest.fixture()
+def lint_module_fixture(
+    tmp_path: Path,
+) -> Callable[[str], Tuple[Path, Path, LintModuleOutputUpdate]]:
+    def inner(base: str) -> Tuple[Path, Path, LintModuleOutputUpdate]:
+        filename = tmp_path / f"{base}.py"
+        expected_output_file = tmp_path / f"{base}.txt"
+        lmou = LintModuleOutputUpdate(
+            test_file=FunctionalTestFile(str(tmp_path), str(filename))
+        )
+        return filename, expected_output_file, lmou
+
+    return inner
+
+
+def test_lint_module_output_update_fail_before(
+    lint_module_fixture: Callable[[str], Tuple[Path, Path, LintModuleOutputUpdate]]
+) -> None:
+    """There is a fail before the output need to be updated."""
+    filename, expected_output_file, lmou = lint_module_fixture("foo")
+    filename.write_text("", encoding="utf8")
+    assert not expected_output_file.exists()
+    with pytest.raises(AssertionError, match="1: disallowed-name"):
+        lmou.runTest()
+    assert not expected_output_file.exists()
+
+
+def test_lint_module_output_update_effective(
+    lint_module_fixture: Callable[[str], Tuple[Path, Path, LintModuleOutputUpdate]]
+) -> None:
+    """The file is updated following a successful tests with wrong output."""
+    filename, expected_output_file, lmou = lint_module_fixture("foo")
+    filename.write_text("# [disallowed-name]\n", encoding="utf8")
+    lmou.runTest()
+    assert (expected_output_file).exists()
+    assert (
+        expected_output_file.read_text(encoding="utf8")
+        == 'disallowed-name:1:0:None:None::"Disallowed name ""foo""":UNDEFINED\n'
+    )
+
+
+def test_lint_module_output_update_remove_useless_txt(
+    lint_module_fixture: Callable[[str], Tuple[Path, Path, LintModuleOutputUpdate]]
+) -> None:
+    """The file is updated following a successful tests with wrong output."""
+    filename, expected_output_file, lmou = lint_module_fixture("fine_name")
+    expected_output_file.write_text("", encoding="utf8")
+    filename.write_text("", encoding="utf8")
+    lmou.runTest()
+    assert not (expected_output_file).exists()