diff --git a/tests/test_categorizer.py b/tests/test_categorizer.py
new file mode 100644
index 00000000..7b10b9b5
--- /dev/null
+++ b/tests/test_categorizer.py
@@ -0,0 +1,38 @@
+from pathlib import Path
+import pytest
+from categorizer import FixtureClass, Speed, auto_classify
+
+def _write(tmp_path: Path, name: str, content: str) -> Path:
+ p = tmp_path / name
+ p.write_text(content, encoding="utf-8")
+ return p
+
+def test_auto_classify_clean_install_filename(tmp_path: Path) -> None:
+ p = _write(tmp_path, "test_clean_install.py", "def test_x(): pass\n")
+ r = auto_classify(p)
+ assert r.fixture_class == FixtureClass.OPT_IN
+
+def test_auto_classify_docker_build_filename(tmp_path: Path) -> None:
+ p = _write(tmp_path, "test_docker_build.py", "def test_x(): pass\n")
+ r = auto_classify(p)
+ assert r.fixture_class == FixtureClass.OPT_IN
+
+def test_auto_classify_live_gui_fixture_in_source(tmp_path: Path) -> None:
+ p = _write(tmp_path, "test_x.py", "def test_x(live_gui): pass\n")
+ r = auto_classify(p)
+ assert r.fixture_class == FixtureClass.LIVE_GUI
+
+def test_auto_classify_mock_app_fixture_in_source(tmp_path: Path) -> None:
+ p = _write(tmp_path, "test_x.py", "def test_x(mock_app): pass\n")
+ r = auto_classify(p)
+ assert r.fixture_class == FixtureClass.MOCK_APP
+
+def test_auto_classify_perf_keyword_in_filename(tmp_path: Path) -> None:
+ p = _write(tmp_path, "test_xyz_stress.py", "def test_x(): pass\n")
+ r = auto_classify(p)
+ assert r.fixture_class == FixtureClass.PERFORMANCE
+
+def test_auto_classify_default_to_unit(tmp_path: Path) -> None:
+ p = _write(tmp_path, "test_command_palette.py", "def test_x(): pass\n")
+ r = auto_classify(p)
+ assert r.fixture_class == FixtureClass.UNIT