DEVX-140: feat: make check_test_isolation configurable via pyproject.toml

tests/unit/test_check_test_isolation.py

@@ -8,14 +8,19 @@ import textwrap
 from pathlib import Path
 from unittest.mock import MagicMock
 
+import pytest
 from click.testing import CliRunner
 
 from devx.tools.check_test_isolation import (
+    HEAVY_MODULE_IMPORTS,
     HELPER_INTERNAL_CALLS,
+    IO_INTERNAL_CALLS,
+    KNOWN_IO_FUNCTIONS,
     KNOWN_SUBPROCESS_HELPERS,
     CallGraph,
     _extract_patch_targets,
     _is_integration_test,
+    _load_test_isolation_config,
     _SubprocessAudit,
     analyze_file,
     analyze_test_files,
@@ -1667,3 +1672,110 @@ class TestIsIntegrationTest:
         item.keywords = {}
         item.fspath = "tests/unit/test_foo.py"
         assert _is_integration_test(item) is False
+
+
+class TestLoadTestIsolationConfig:
+    """Tests for _load_test_isolation_config — project-specific rule merging."""
+
+    def test_merges_io_functions(self, tmp_path: Path, monkeypatch: pytest.MonkeyPatch) -> None:
+        """Project-specific io_functions are added to KNOWN_IO_FUNCTIONS."""
+        pyproject = tmp_path / "pyproject.toml"
+        pyproject.write_text(
+            '[tool.devx.check_test_isolation]\nio_functions = { "my_custom_io" = "reads from disk" }\n'
+        )
+        monkeypatch.chdir(tmp_path)
+        _load_test_isolation_config()
+        assert "my_custom_io" in KNOWN_IO_FUNCTIONS
+        assert KNOWN_IO_FUNCTIONS["my_custom_io"] == "reads from disk"
+
+    def test_merges_subprocess_helpers(self, tmp_path: Path, monkeypatch: pytest.MonkeyPatch) -> None:
+        """Project-specific subprocess_helpers are added."""
+        pyproject = tmp_path / "pyproject.toml"
+        pyproject.write_text(
+            '[tool.devx.check_test_isolation]\nsubprocess_helpers = { "my_sp_helper" = "calls subprocess.run" }\n'
+        )
+        monkeypatch.chdir(tmp_path)
+        _load_test_isolation_config()
+        assert "my_sp_helper" in KNOWN_SUBPROCESS_HELPERS
+
+    def test_merges_helper_internal_calls(self, tmp_path: Path, monkeypatch: pytest.MonkeyPatch) -> None:
+        """Project-specific helper_internal_calls are merged."""
+        pyproject = tmp_path / "pyproject.toml"
+        pyproject.write_text(
+            '[tool.devx.check_test_isolation]\nhelper_internal_calls = { "my_helper" = ["subprocess", "run_cmd"] }\n'
+        )
+        monkeypatch.chdir(tmp_path)
+        _load_test_isolation_config()
+        assert "my_helper" in HELPER_INTERNAL_CALLS
+        assert HELPER_INTERNAL_CALLS["my_helper"] == {"subprocess", "run_cmd"}
+
+    def test_merges_io_internal_calls(self, tmp_path: Path, monkeypatch: pytest.MonkeyPatch) -> None:
+        """Project-specific io_internal_calls are merged."""
+        pyproject = tmp_path / "pyproject.toml"
+        pyproject.write_text(
+            '[tool.devx.check_test_isolation]\nio_internal_calls = { "my_io_func" = ["open", "yaml"] }\n'
+        )
+        monkeypatch.chdir(tmp_path)
+        _load_test_isolation_config()
+        assert "my_io_func" in IO_INTERNAL_CALLS
+        assert IO_INTERNAL_CALLS["my_io_func"] == {"open", "yaml"}
+
+    def test_merges_heavy_module_imports(self, tmp_path: Path, monkeypatch: pytest.MonkeyPatch) -> None:
+        """Project-specific heavy_module_imports are merged."""
+        pyproject = tmp_path / "pyproject.toml"
+        pyproject.write_text('[tool.devx.check_test_isolation]\nheavy_module_imports = { "mymodule" = 150.0 }\n')
+        monkeypatch.chdir(tmp_path)
+        _load_test_isolation_config()
+        assert "mymodule" in HEAVY_MODULE_IMPORTS
+        assert HEAVY_MODULE_IMPORTS["mymodule"] == 150.0
+
+    def test_no_config_section_is_noop(self, tmp_path: Path, monkeypatch: pytest.MonkeyPatch) -> None:
+        """Missing [tool.devx.check_test_isolation] section is a no-op."""
+        pyproject = tmp_path / "pyproject.toml"
+        pyproject.write_text('[tool.devx]\nother_key = "value"\n')
+        monkeypatch.chdir(tmp_path)
+        before_io = dict(KNOWN_IO_FUNCTIONS)
+        _load_test_isolation_config()
+        assert before_io == KNOWN_IO_FUNCTIONS
+
+    def test_no_pyproject_is_noop(self, tmp_path: Path, monkeypatch: pytest.MonkeyPatch) -> None:
+        """No pyproject.toml at all is a no-op."""
+        monkeypatch.chdir(tmp_path)
+        before = dict(KNOWN_SUBPROCESS_HELPERS)
+        _load_test_isolation_config()
+        assert before == KNOWN_SUBPROCESS_HELPERS
+
+    def test_non_dict_config_is_noop(self, tmp_path: Path, monkeypatch: pytest.MonkeyPatch) -> None:
+        """A non-dict check_test_isolation section is a no-op."""
+        pyproject = tmp_path / "pyproject.toml"
+        pyproject.write_text('[tool.devx]\ncheck_test_isolation = "not_a_dict"\n')
+        monkeypatch.chdir(tmp_path)
+        before = dict(HEAVY_MODULE_IMPORTS)
+        _load_test_isolation_config()
+        assert before == HEAVY_MODULE_IMPORTS
+
+    def test_invalid_entry_types_are_skipped(self, tmp_path: Path, monkeypatch: pytest.MonkeyPatch) -> None:
+        """Entries with wrong types (non-str values) are silently skipped."""
+        pyproject = tmp_path / "pyproject.toml"
+        pyproject.write_text(
+            "[tool.devx.check_test_isolation]\n"
+            'io_functions = { "good_func" = "desc", "bad_func" = 123 }\n'
+            'heavy_module_imports = { "good_mod" = 100.0, "bad_mod" = "fast" }\n'
+        )
+        monkeypatch.chdir(tmp_path)
+        _load_test_isolation_config()
+        assert "good_func" in KNOWN_IO_FUNCTIONS
+        assert "bad_func" not in KNOWN_IO_FUNCTIONS
+        assert "good_mod" in HEAVY_MODULE_IMPORTS
+        assert "bad_mod" not in HEAVY_MODULE_IMPORTS
+
+    def test_extends_without_replacing_defaults(self, tmp_path: Path, monkeypatch: pytest.MonkeyPatch) -> None:
+        """Project config adds to defaults without removing them."""
+        pyproject = tmp_path / "pyproject.toml"
+        pyproject.write_text('[tool.devx.check_test_isolation]\nio_functions = { "project_func" = "project I/O" }\n')
+        monkeypatch.chdir(tmp_path)
+        _load_test_isolation_config()
+        # Default entries still present
+        assert "get_pat" in KNOWN_IO_FUNCTIONS
+        # Project entry added
+        assert "project_func" in KNOWN_IO_FUNCTIONS