Adds warning when invalid error codes are parsed for ignore or extend-ignore from config file

tests/unit/plugins/finder_test.py

@@ -31,37 +31,6 @@ def _loaded(plugin=None, obj=None, parameters=None):
     return finder.LoadedPlugin(plugin, obj, parameters)
 
 
-@pytest.mark.parametrize(
-    "s",
-    (
-        "E",
-        "E1",
-        "E123",
-        "ABC",
-        "ABC1",
-        "ABC123",
-    ),
-)
-def test_valid_plugin_prefixes(s):
-    assert finder.VALID_CODE.match(s)
-
-
-@pytest.mark.parametrize(
-    "s",
-    (
-        "",
-        "A1234",
-        "ABCD",
-        "abc",
-        "a-b",
-        "☃",
-        "A𝟗",
-    ),
-)
-def test_invalid_plugin_prefixes(s):
-    assert finder.VALID_CODE.match(s) is None
-
-
 def test_loaded_plugin_entry_name_vs_display_name():
     loaded = _loaded(_plugin(package="package-name", ep=_ep(name="Q")))
     assert loaded.entry_name == "Q"

tests/unit/test_defaults.py

@@ -0,0 +1,36 @@
+from __future__ import annotations
+
+import pytest
+
+from flake8.defaults import VALID_CODE_PREFIX
+
+
+@pytest.mark.parametrize(
+    "s",
+    (
+        "E",
+        "E1",
+        "E123",
+        "ABC",
+        "ABC1",
+        "ABC123",
+    ),
+)
+def test_valid_plugin_prefixes(s):
+    assert VALID_CODE_PREFIX.match(s)
+
+
+@pytest.mark.parametrize(
+    "s",
+    (
+        "",
+        "A1234",
+        "ABCD",
+        "abc",
+        "a-b",
+        "☃",
+        "A𝟗",
+    ),
+)
+def test_invalid_plugin_prefixes(s):
+    assert VALID_CODE_PREFIX.match(s) is None

tests/unit/test_options_config.py

@@ -220,3 +220,35 @@ def test_parse_config_ignores_unknowns(tmp_path, opt_manager, caplog):
 def test_load_config_missing_file_raises_exception(capsys):
     with pytest.raises(exceptions.ExecutionError):
         config.load_config("foo.cfg", [])
+
+
+def test_invalid_ignore_codes_raise_error(tmpdir, opt_manager):
+    tmpdir.join("setup.cfg").write("[flake8]\nignore = E203, //comment")
+    with tmpdir.as_cwd():
+        cfg, _ = config.load_config("setup.cfg", [], isolated=False)
+
+    with pytest.raises(ValueError) as excinfo:
+        config.parse_config(opt_manager, cfg, tmpdir)
+
+    expected = (
+        "Error code '//comment' supplied to 'ignore' option "
+        "does not match '^[A-Z]{1,3}[0-9]{0,3}$'"
+    )
+    (msg,) = excinfo.value.args
+    assert msg == expected
+
+
+def test_invalid_extend_ignore_codes_raise_error(tmpdir, opt_manager):
+    tmpdir.join("setup.cfg").write("[flake8]\nextend-ignore = E203, //comment")
+    with tmpdir.as_cwd():
+        cfg, _ = config.load_config("setup.cfg", [], isolated=False)
+
+    with pytest.raises(ValueError) as excinfo:
+        config.parse_config(opt_manager, cfg, tmpdir)
+
+    expected = (
+        "Error code '//comment' supplied to 'extend-ignore' option "
+        "does not match '^[A-Z]{1,3}[0-9]{0,3}$'"
+    )
+    (msg,) = excinfo.value.args
+    assert msg == expected