ML-192: add high value missing tests

- Record editing + cover search
- Barcode scan errors + cart editing
- Notes
- Scrobble rules application over set of tracks
- Image conversion

test/music_library/assets/image_test.exs

@@ -11,4 +11,23 @@ defmodule MusicLibrary.Assets.ImageTest do
       assert cover_data !== resized_cover
     end
   end
+
+  describe "convert/3" do
+    test "same-format passthrough returns original binary unchanged" do
+      data = Image.fallback_data()
+      assert {:ok, result} = Image.convert(data, "image/jpeg", "image/jpeg")
+      assert result == data
+    end
+
+    test "converts JPEG to WebP successfully" do
+      data = Image.fallback_data()
+      assert {:ok, webp_data} = Image.convert(data, "image/jpeg", "image/webp")
+      assert webp_data != data
+      assert byte_size(webp_data) > 0
+    end
+
+    test "returns error tuple for invalid image data" do
+      assert {:error, _reason} = Image.convert("not an image", "image/jpeg", "image/webp")
+    end
+  end
 end

test/music_library/scrobble_rules_test.exs

@@ -421,6 +421,43 @@ defmodule MusicLibrary.ScrobbleRulesTest do
       assert {:ok, 0} = ScrobbleRules.apply_all_artist_rules([])
     end
 
+    test "apply_all_rules/1 only updates supplied track subset and leaves other matching tracks unchanged" do
+      rule =
+        scrobble_rule_fixture(%{
+          match_value: "Test Subset Album",
+          target_musicbrainz_id: "99999999-9999-9999-9999-999999999999"
+        })
+
+      # Use explicit scrobbled_at_uts values (SQLite second precision requires this for ordering)
+      now = System.system_time(:second)
+
+      supplied_track =
+        scrobbled_track_fixture(%{
+          scrobbled_at_uts: now,
+          album: %{title: "Test Subset Album"},
+          artist: %{name: "Test Artist"}
+        })
+
+      non_supplied_matching_track =
+        scrobbled_track_fixture(%{
+          scrobbled_at_uts: now + 1,
+          album: %{title: "Test Subset Album"},
+          artist: %{name: "Test Artist"}
+        })
+
+      results = ScrobbleRules.apply_all_rules([supplied_track])
+      assert results != []
+
+      # The supplied track should have been updated
+      updated_supplied = Repo.get(Track, supplied_track.scrobbled_at_uts)
+      assert updated_supplied.album.musicbrainz_id == rule.target_musicbrainz_id
+
+      # The non-supplied matching track should NOT have been updated
+      # (musicbrainz_id remains as stored, which is nil for unset embedded fields)
+      updated_non_supplied = Repo.get(Track, non_supplied_matching_track.scrobbled_at_uts)
+      assert updated_non_supplied.album.musicbrainz_id == nil
+    end
+
     test "apply_all_rules/0 batches rules by type" do
       # Create multiple rules of each type
       _album_rule1 = scrobble_rule_fixture(@valid_album_attrs)