Add runtime checkable protocol for checking gallery compatibility.

tests/unit_tests/test_gallery.py

@@ -1,5 +1,81 @@
 """Tests that captures have the expected metadata."""
 
+import logging
+
+from pydantic import BaseModel
+
+from labthings_fastapi.testing import create_thing_without_server
+
+from openflexure_microscope_server.things import OFMThing
+from openflexure_microscope_server.things.gallery import (
+    GalleryCompatibleThing,
+    GalleryThing,
+)
+
+from ..shared_utils.lt_test_utils import LabThingsTestEnv
+
+
+class MockGalleryData(BaseModel):
+    """Mock gallery data."""
+
+    mock: str
+    foobar: int
+
+
+class MinimalGalleryClass:
+    """A class that provides data to the gallery needs but is NOT a thing.
+
+    This should fail the protocol check as it is not an OFMThing
+    """
+
+    gallery_data_name: str = "Mock"
+
+    gallery_data_schema: type[BaseModel] = MockGalleryData
+
+    def get_gallery_data(self) -> list[BaseModel]:
+        """Return a list of Mock Gallery Data."""
+        return [MockGalleryData(mock="mock", foobar="foobar")]
+
+
+class MinimalGallerySource(OFMThing, MinimalGalleryClass):
+    """Minimal example of a Thing that can show in the gallery.
+
+    Mixes MinimalGalleryClass into OFMThing to be recognised by the protocol.
+    """
+
+    show_in_gallery = True
+
+
+class BadGallerySource(OFMThing):
+    """An OFMThing that almost defines enough to show in the gallery.
+
+    Shouldn't math the protocol as ``gallery_data_name`` is missing.
+    """
+
+    show_in_gallery = True
+
+    gallery_data_schema: type[BaseModel] = MockGalleryData
+
+    def get_gallery_data(self) -> list[BaseModel]:
+        """Return a list of Mock Gallery Data."""
+        return [MockGalleryData(mock="mock", foobar="foobar")]
+
+
+def test_gallery_compatible_protocol():
+    """Check the gallery compatible protocol detects compatible classes only."""
+    # Minimal class has the gallery specific methods but is not an OFMThing.
+    assert not isinstance(MinimalGalleryClass(), GalleryCompatibleThing)
+
+    # BadGallerySource is an OFM Thing but is missing one of the required properties.
+    assert not isinstance(
+        create_thing_without_server(BadGallerySource), GalleryCompatibleThing
+    )
+
+    # MinimalGallerySource should match!
+    assert isinstance(
+        create_thing_without_server(MinimalGallerySource), GalleryCompatibleThing
+    )
+
 
 def test_gallery_thing_finds_all_providers(simulation_test_env):
     """Check the gallery identifies the correct Things that will provide data."""
@@ -15,3 +91,32 @@ def test_gallery_thing_finds_all_providers(simulation_test_env):
     assert snake_workflow not in gallery.gallery_providing_things.values()
     assert camera not in gallery.gallery_providing_things.values()
     assert smart_scan in gallery.gallery_providing_things.values()
+
+    assert not isinstance(snake_workflow, GalleryCompatibleThing)
+    assert isinstance(smart_scan, GalleryCompatibleThing)
+
+
+def test_gallery_logs_for_bad_providers(caplog):
+    """Test that an error is logged if a gallery source doesn't match the protocol."""
+    # Create a config with the minimal and the bad thing
+    things = {
+        "minimal_thing": MinimalGallerySource,
+        "bad_thing": BadGallerySource,
+        "gallery": GalleryThing,
+    }
+    with caplog.at_level(logging.INFO):
+        # Start the server
+        with LabThingsTestEnv(
+            things=things, application_config={"data_folder": "./openflexure/data/"}
+        ) as env:
+            gallery = env.get_thing_by_name("gallery")
+            # Minimal thing is listed as a gallery provider
+            assert "minimal_thing" in gallery.gallery_providing_things
+            # Bad thing isn't as the protocol doesn't match
+            assert "bad_thing" not in gallery.gallery_providing_things
+
+        # There is an error logged about bad_thing
+        assert len(caplog.records) == 1
+        record = caplog.records[0]
+        assert "Data from bad_thing cannot be shown in gallery" in record.message
+        assert record.levelname == "ERROR"