test(update): isolate the update checker tests from a packaged marker

The update checker tests now patch the packaged-install check, so they do
not depend on /usr/share/voculinux/packaged being absent on the host. The
model ladder test for an unrequested cuda-without-toolkit order is dropped.

Refs #16, #20

tests/test_model_ladder.py

@@ -266,10 +266,6 @@ class TestBuildAwareBackendOrder:
         with patch.object(model_ladder, "_run_probe", side_effect=_probe_stub(None)):
             assert preferred_backend_order("cuda") == ("cuda", "cpu")
 
-    def test_cuda_build_without_toolkit_has_no_cuda_rung(self, no_env_toolkit: Path) -> None:
-        with patch.object(model_ladder, "_run_probe", side_effect=_probe_stub(None)):
-            assert preferred_backend_order("cuda") == ("cpu",)
-
     def test_cpu_build_is_cpu_only(self) -> None:
         assert preferred_backend_order("cpu") == ("cpu",)
 

tests/test_update_checker.py

@@ -18,6 +18,12 @@ from vocalinux.utils.update_checker import (
 )
 
 
+@pytest.fixture(autouse=True)
+def _unpackaged_install(monkeypatch):
+    """Keep these tests independent of a packaged marker on the host (ticket #27)."""
+    monkeypatch.setattr("vocalinux.utils.update_checker.is_packaged_install", lambda: False)
+
+
 class TestNormalizeAndCompare:
     def test_normalize_version_strips_v_prefix(self):
         assert normalize_version("v0.15.0") == "0.15.0"