Improve coverage of ``argparse`` (#6332)

* Fix coverage of ``pylint/config/config_file_parser.py``
* Fix coverage of ``pylint/config/argument.py``

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

3 files changed, 47 insertions, 0 deletions

diff --git a/tests/config/functional/toml/toml_without_pylint.toml b/tests/config/functional/toml/toml_without_pylint.toml
new file mode 100644
index 000000000..ede9086e4
--- /dev/null
+++ b/tests/config/functional/toml/toml_without_pylint.toml
@@ -0,0 +1,6 @@
+# Check that we do nothing if there is no pylint configuration
+
+[tool.othertool]
+disable = "logging-not-lazy,logging-format-interpolation"
+jobs = "10"
+reports = "yes"
diff --git a/tests/config/test_config.py b/tests/config/test_config.py
index 89b6198a4..10e3fa4c1 100644
--- a/tests/config/test_config.py
+++ b/tests/config/test_config.py
@@ -7,6 +7,7 @@ from __future__ import annotations
 import os
 from pathlib import Path
 
+import pytest
 from pytest import CaptureFixture
 
 from pylint.lint import Run
@@ -58,3 +59,27 @@ def test_unknown_message_id(capsys: CaptureFixture) -> None:
     Run([str(EMPTY_MODULE), "--disable=12345"], exit=False)
     output = capsys.readouterr()
     assert "Command line:1:0: E0012: Bad option value for --disable." in output.out
+
+
+def test_unknown_confidence(capsys: CaptureFixture) -> None:
+    """Check that we correctly error an unknown confidence value."""
+    with pytest.raises(SystemExit):
+        Run([str(EMPTY_MODULE), "--confidence=UNKNOWN_CONFIG"], exit=False)
+    output = capsys.readouterr()
+    assert "argument --confidence: UNKNOWN_CONFIG should be in" in output.err
+
+
+def test_unknown_yes_no(capsys: CaptureFixture) -> None:
+    """Check that we correctly error on an unknown yes/no value."""
+    with pytest.raises(SystemExit):
+        Run([str(EMPTY_MODULE), "--reports=maybe"], exit=False)
+    output = capsys.readouterr()
+    assert "Invalid yn value 'maybe', should be in " in output.err
+
+
+def test_unknown_py_version(capsys: CaptureFixture) -> None:
+    """Check that we correctly error on an unknown python-version."""
+    with pytest.raises(SystemExit):
+        Run([str(EMPTY_MODULE), "--py-version=the-newest"], exit=False)
+    output = capsys.readouterr()
+    assert "the-newest has an invalid format, should be a version string." in output.err
diff --git a/tests/config/test_find_default_config_files.py b/tests/config/test_find_default_config_files.py
index 7d25b4e8b..373099f08 100644
--- a/tests/config/test_find_default_config_files.py
+++ b/tests/config/test_find_default_config_files.py
@@ -14,9 +14,11 @@ from collections.abc import Iterator
 from pathlib import Path
 
 import pytest
+from pytest import CaptureFixture
 
 from pylint import config, testutils
 from pylint.config.find_default_config_files import _cfg_has_config, _toml_has_config
+from pylint.lint.run import Run
 
 
 @pytest.fixture
@@ -143,6 +145,20 @@ def test_pylintrc_parentdir_no_package() -> None:
                 assert next(config.find_default_config_files(), None) == expected
 
 
+@pytest.mark.usefixtures("pop_pylintrc")
+def test_verbose_output_no_config(capsys: CaptureFixture) -> None:
+    """Test that we print a log message in verbose mode with no file."""
+    with tempdir() as chroot:
+        with fake_home():
+            chroot_path = Path(chroot)
+            testutils.create_files(["a/b/c/d/__init__.py"])
+            os.chdir(chroot_path / "a/b/c")
+            with pytest.raises(SystemExit):
+                Run(["--verbose"])
+            out = capsys.readouterr()
+            assert "No config file found, using default configuration" in out.err
+
+
 @pytest.mark.parametrize(
     "content,expected",
     [