1 files changed, 127 insertions, 0 deletions
diff --git a/tests/config/test_config.py b/tests/config/test_config.py
new file mode 100644
index 000000000..7a4b09639
--- /dev/null
+++ b/tests/config/test_config.py
@@ -0,0 +1,127 @@
+# pylint: disable=missing-module-docstring, missing-function-docstring, protected-access
+import os
+import unittest.mock
+from pathlib import PosixPath
+
+import pytest
+
+import pylint.lint
+from pylint.config import OptionsManagerMixIn
+from pylint.lint.run import Run
+
+
+def check_configuration_file_reader(config_file: PosixPath) -> Run:
+    """Initialize pylint with the given configuration file and check that
+    what we initialized the linter with what was expected.
+    """
+    args = ["--rcfile", str(config_file), __file__]
+    # If we used `pytest.raises(SystemExit)`, the `runner` variable
+    # would not be accessible outside the `with` block.
+    with unittest.mock.patch("sys.exit") as mocked_exit:
+        # Do not actually run checks, that could be slow. Do not mock
+        # `Pylinter.check`: it calls `Pylinter.initialize` which is
+        # needed to properly set up messages inclusion/exclusion
+        # in `_msg_states`, used by `is_message_enabled`.
+        with unittest.mock.patch("pylint.lint.pylinter.check_parallel"):
+            runner = pylint.lint.Run(args)
+
+    # "logging-not-lazy" and "logging-format-interpolation"
+    expected_disabled = {"W1201", "W1202"}
+    for msgid in expected_disabled:
+        assert not runner.linter.is_message_enabled(msgid)
+    assert runner.linter.config.jobs == 10
+    assert runner.linter.config.reports
+
+    mocked_exit.assert_called_once_with(0)
+    return runner
+
+
+def test_can_read_ini(tmp_path: PosixPath) -> None:
+    # Check that we can read the "regular" INI .pylintrc file
+    config_file = tmp_path / ".pylintrc"
+    config_file.write_text(
+        """
+[messages control]
+disable = logging-not-lazy,logging-format-interpolation
+jobs = 10
+reports = yes
+"""
+    )
+    check_configuration_file_reader(config_file)
+
+
+def test_can_read_setup_cfg(tmp_path: PosixPath) -> None:
+    # Check that we can read a setup.cfg (which is an INI file where
+    # section names are prefixed with "pylint."
+    config_file = tmp_path / "setup.cfg"
+    config_file.write_text(
+        """
+[pylint.messages control]
+disable = logging-not-lazy,logging-format-interpolation
+jobs = 10
+reports = yes
+"""
+    )
+    check_configuration_file_reader(config_file)
+
+
+def test_can_read_toml(tmp_path: PosixPath) -> None:
+    # Check that we can read a TOML file where lists and integers are
+    # expressed as strings.
+    config_file = tmp_path / "pyproject.toml"
+    config_file.write_text(
+        """
+[tool.pylint."messages control"]
+disable = "logging-not-lazy,logging-format-interpolation"
+jobs = "10"
+reports = "yes"
+"""
+    )
+    check_configuration_file_reader(config_file)
+
+
+def test_can_read_toml_rich_types(tmp_path: PosixPath) -> None:
+    # Check that we can read a TOML file where lists, integers and
+    # booleans are expressed as such (and not as strings), using TOML
+    # type system.
+    config_file = tmp_path / "pyproject.toml"
+    config_file.write_text(
+        """
+[tool.pylint."messages control"]
+disable = [
+    "logging-not-lazy",
+    "logging-format-interpolation",
+]
+jobs = 10
+reports = true
+"""
+    )
+    check_configuration_file_reader(config_file)
+
+
+def test_can_read_env_variable(tmp_path: PosixPath) -> None:
+    # Check that we can read the "regular" INI .pylintrc file
+    # if it has an environment variable.
+    config_file = tmp_path / "pyproject.toml"
+    config_file.write_text(
+        """
+[tool.pylint."messages control"]
+disable = "logging-not-lazy,logging-format-interpolation"
+jobs = "10"
+reports = "yes"
+"""
+    )
+    os.environ["tmp_path_env"] = str(tmp_path / "pyproject.toml")
+    options_manager_mix_in = OptionsManagerMixIn("", "${tmp_path_env}")
+    options_manager_mix_in.read_config_file("${tmp_path_env}")
+
+    def test_read_config_file() -> None:
+        with pytest.raises(OSError):
+            options_manager_mix_in.read_config_file("${tmp_path_en}")
+
+    test_read_config_file()
+    options_manager_mix_in.load_config_file()
+    section = options_manager_mix_in.cfgfile_parser.sections()[0]
+    jobs, jobs_nr = options_manager_mix_in.cfgfile_parser.items(section)[1]
+    assert jobs == "jobs"
+    assert jobs_nr == "10"