More complete testing of code that runs stitching subprocess.

tests/mock_things/mock_camera.py

@@ -11,18 +11,24 @@ from openflexure_microscope_server.background_detect import (
     BackgroundDetectorStatus,
     ColourChannelDetectSettings,
 )
+from unittest.mock import Mock, PropertyMock
 
 
-class MockCameraThing:
+class MockCameraThing(Mock):
     """A mock camera Thing that imports no code from ``BaseCamera``.
 
     The class needs functionality added to it over time as more complex
-    mocking is needed. It imports no code from ``BaseCamera or any other
+    mocking is needed. It imports no code from ``BaseCamera`` or any other
     camera Thing, so that coverage is not artificially inflated.
     """
 
-    background_detector_status = BackgroundDetectorStatus(
-        ready=True,
-        settings=ColourChannelDetectSettings().model_dump(),
-        settings_schema={"fake": "schema"},
-    )
+    def __init__(self, *args, **kwargs):
+        super().__init__(*args, **kwargs)
+
+        self.background_detector_status = PropertyMock(
+            return_value=BackgroundDetectorStatus(
+                ready=True,
+                settings=ColourChannelDetectSettings().model_dump(),
+                settings_schema={"fake": "schema"},
+            )
+        )