Simplify frame number extraction test by splitting it

tests/test_unit/test_load_bboxes.py

@@ -456,38 +456,77 @@ def test_extract_confidence_from_via_tracks_df(
         ),
     ],
 )
+def test_extract_frame_number_from_via_tracks_df_filenames(
+    create_df_input_via_tracks,
+    via_file_path,
+    expected_frame_array,
+):
+    """Test that the function correctly extracts the frame number values from
+    the images' filenames.
+    """
+    # create the dataframe with the frame number
+    df = create_df_input_via_tracks(
+        via_file_path,
+        small=True,
+    )
+
+    # the VIA tracks .csv files have no frames defined under the
+    # "file_attributes" so the frame numbers should be extracted
+    # from the filenames
+    assert not all(["frame" in row for row in df["file_attributes"]])
+
+    # extract frame number from df
+    frame_array = load_bboxes._extract_frame_number_from_via_tracks_df(df)
+
+    assert np.array_equal(frame_array, expected_frame_array)
+
+
 @pytest.mark.parametrize(
-    "attribute_column_additions",
+    "via_file_path, attribute_column_additions, expected_frame_array",
     [
-        (None),  # taking "frame" from the images' filenames
-        ({"file_attributes": []}),  # taking "frame" from the "file_attributes"
+        (
+            pytest.DATA_PATHS.get("VIA_multiple-crabs_5-frames_labels.csv"),
+            {"file_attributes": [{"frame": 222}]},
+            np.ones(
+                3,
+            )
+            * 222,
+        ),
+        (
+            pytest.DATA_PATHS.get("VIA_single-crab_MOCA-crab-1.csv"),
+            {
+                "file_attributes": [
+                    {"frame": 218},
+                    {"frame": 219},
+                    {"frame": 220},
+                ]
+            },
+            np.array([218, 219, 220]),
+        ),
     ],
 )
-def test_extract_frame_number_from_via_tracks_df(
+def test_extract_frame_number_from_via_tracks_df_file_attributes(
     create_df_input_via_tracks,
     via_file_path,
     attribute_column_additions,
     expected_frame_array,
 ):
     """Test that the function correctly extracts the frame number values from
-    the VIA dataframe.
-    """
-    # If required: define the list of frames
-    # to append to the dataframe as file attributes
-    if attribute_column_additions:
-        attribute_column_additions["file_attributes"] = [
-            {"frame": f.item()} for f in expected_frame_array
-        ]
+    the file attributes column.
 
-    # create the dataframe with the frame number
-    # (either from the file name or from the file attributes)
+    The frame number defined under the "file_attributes" column
+    should take precedence over the frame numbers encoded in the filenames.
+    """
+    # Create the dataframe with the frame number stored in
+    # the file_attributes column
     df = create_df_input_via_tracks(
         via_file_path,
         small=True,
         attribute_column_additions=attribute_column_additions,
     )
 
-    # extract frame number from df
+    # extract frame number from the dataframe
+    # (should take precedence over the frame numbers in the filenames)
     frame_array = load_bboxes._extract_frame_number_from_via_tracks_df(df)
 
     assert np.array_equal(frame_array, expected_frame_array)