Make functional tests always go through config initialization (#5594)

Co-authored-by: Pierre Sassoulas <pierre.sassoulas@gmail.com>

3 files changed, 30 insertions, 11 deletions

diff --git a/pylint/config/config_initialization.py b/pylint/config/config_initialization.py
index 46031bae3..d03822030 100644
--- a/pylint/config/config_initialization.py
+++ b/pylint/config/config_initialization.py
@@ -2,6 +2,7 @@
 # For details: https://github.com/PyCQA/pylint/blob/main/LICENSE
 
 import sys
+from pathlib import Path
 from typing import TYPE_CHECKING, List, Optional, Union
 
 from pylint import reporters
@@ -15,7 +16,7 @@ def _config_initialization(
     linter: "PyLinter",
     args_list: List[str],
     reporter: Union[reporters.BaseReporter, reporters.MultiReporter, None] = None,
-    config_file: Optional[str] = None,
+    config_file: Union[None, str, Path] = None,
     verbose_mode: Optional[bool] = None,
 ) -> List[str]:
     """Parse all available options, read config files and command line arguments and
diff --git a/pylint/testutils/lint_module_test.py b/pylint/testutils/lint_module_test.py
index e89f82ace..8dbf5e60b 100644
--- a/pylint/testutils/lint_module_test.py
+++ b/pylint/testutils/lint_module_test.py
@@ -7,8 +7,9 @@ import platform
 import sys
 from collections import Counter
 from io import StringIO
+from pathlib import Path
 from typing import Counter as CounterType
-from typing import Dict, List, Optional, TextIO, Tuple
+from typing import Dict, List, Optional, TextIO, Tuple, Union
 
 import pytest
 from _pytest.config import Config
@@ -28,6 +29,8 @@ from pylint.testutils.reporter_for_tests import FunctionalTestReporter
 
 MessageCounter = CounterType[Tuple[int, str]]
 
+PYLINTRC = Path(__file__).parent / "testing_pylintrc"
+
 
 class LintModuleTest:
     maxDiff = None
@@ -37,21 +40,27 @@ class LintModuleTest:
     ) -> None:
         _test_reporter = FunctionalTestReporter()
         self._linter = PyLinter()
-        self._linter.set_reporter(_test_reporter)
         self._linter.config.persistent = 0
         checkers.initialize(self._linter)
-        self._linter.disable("suppressed-message")
-        self._linter.disable("locally-disabled")
-        self._linter.disable("useless-suppression")
+
+        # See if test has its own .rc file, if so we use that one
+        rc_file: Union[Path, str] = PYLINTRC
         try:
-            _config_initialization(
-                self._linter,
-                [test_file.source],
-                config_file=test_file.option_file,
-            )
+            rc_file = test_file.option_file
+            self._linter.disable("suppressed-message")
+            self._linter.disable("locally-disabled")
+            self._linter.disable("useless-suppression")
         except NoFileError:
             pass
 
+        try:
+            args = [test_file.source]
+        except NoFileError:
+            # If we're still raising NoFileError the actual source file doesn't exist
+            args = [""]
+        _config_initialization(
+            self._linter, args_list=args, config_file=rc_file, reporter=_test_reporter
+        )
         self._test_file = test_file
         self._config = config
         self._check_end_position = (
diff --git a/pylint/testutils/testing_pylintrc b/pylint/testutils/testing_pylintrc
new file mode 100644
index 000000000..ba5318b51
--- /dev/null
+++ b/pylint/testutils/testing_pylintrc
@@ -0,0 +1,9 @@
+# A bare minimum pylintrc used for the functional tests that don't specify
+# their own settings.
+
+[MESSAGES CONTROL]
+
+disable=
+    suppressed-message,
+    locally-disabled,
+    useless-suppression,