learningcircuit--local-deep-research/tests/hooks/test_check_shadow_tests.py

"""Tests for the check-shadow-tests pre-commit hook.

Verifies that the hook flags test modules with no ``local_deep_research``
import (shadow tests) while allowing real tests, the ``# allow:
no-sut-import`` opt-out, and non-test modules.
"""

import subprocess
import sys
import tempfile
from pathlib import Path

HOOK_SCRIPT = (
    Path(__file__).parent.parent.parent
    / ".pre-commit-hooks"
    / "check-shadow-tests.py"
)


def _run_hook(content: str, filename: str = "test_sample.py"):
    """Write content to a temp file named `filename` and run the hook."""
    with tempfile.TemporaryDirectory() as d:
        path = Path(d) / filename
        path.write_text(content, encoding="utf-8")
        return subprocess.run(
            [sys.executable, str(HOOK_SCRIPT), str(path)],
            capture_output=True,
            text=True,
        )


class TestFlagsShadowTests:
    """Test modules that exercise no SUT must be flagged."""

    def test_inline_logic_no_sut_import(self):
        result = _run_hook(
            "import datetime\n\n"
            "def test_year():\n"
            "    assert datetime.date(2020, 1, 1).year == 2020\n"
        )
        assert result.returncode == 1
        assert "Shadow tests detected" in result.stdout

    def test_only_stdlib_imports(self):
        result = _run_hook(
            "import json\n\ndef test_roundtrip():\n"
            '    assert json.loads(json.dumps({"a": 1})) == {"a": 1}\n'
        )
        assert result.returncode == 1

    def test_type_checking_only_import_flagged(self):
        # SUT imported only for type hints never runs, so it's still a shadow.
        result = _run_hook(
            "from typing import TYPE_CHECKING\n\n"
            "if TYPE_CHECKING:\n"
            "    from local_deep_research.config import Thing\n\n"
            "def test_x():\n    assert 1 == 1\n"
        )
        assert result.returncode == 1


class TestAllowsRealTests:
    """Files that import the SUT — or are exempt — must pass."""

    def test_from_import_passes(self):
        result = _run_hook(
            "from local_deep_research.config import x\n\n"
            "def test_x():\n    assert x\n"
        )
        assert result.returncode == 0

    def test_src_prefixed_import_passes(self):
        result = _run_hook(
            "from src.local_deep_research import app\n\n"
            "def test_app():\n    assert app\n"
        )
        assert result.returncode == 0

    def test_plain_import_passes(self):
        result = _run_hook(
            "import local_deep_research\n\n"
            "def test_pkg():\n    assert local_deep_research\n"
        )
        assert result.returncode == 0

    def test_type_checking_plus_runtime_import_passes(self):
        # A type-only import under TYPE_CHECKING is ignored, but the runtime
        # import at module level still counts.
        result = _run_hook(
            "from typing import TYPE_CHECKING\n\n"
            "if TYPE_CHECKING:\n"
            "    from local_deep_research.config import Thing\n\n"
            "from local_deep_research.config import run\n\n"
            "def test_x():\n    assert run\n"
        )
        assert result.returncode == 0

    def test_allow_marker_exempts(self):
        result = _run_hook(
            "# allow: no-sut-import — guardian test asserting repo structure\n"
            "import os\n\ndef test_repo():\n    assert os.path.exists('.')\n"
        )
        assert result.returncode == 0

    def test_marker_without_reason_does_not_exempt(self):
        # The reason text after the marker is mandatory.
        result = _run_hook(
            "# allow: no-sut-import\n"
            "import os\n\ndef test_repo():\n    assert os.path.exists('.')\n"
        )
        assert result.returncode == 1


class TestScope:
    """Only pytest test modules are inspected."""

    def test_non_test_module_ignored(self):
        result = _run_hook("import datetime\n", filename="helpers.py")
        assert result.returncode == 0

    def test_conftest_ignored(self):
        result = _run_hook("import datetime\n", filename="conftest.py")
        assert result.returncode == 0

    def test_underscore_test_suffix_inspected(self):
        result = _run_hook(
            "import datetime\n\ndef test_x():\n    assert datetime\n",
            filename="sample_test.py",
        )
        assert result.returncode == 1