test: add TestVideoActivityFEFunctional

Tests VAFE using a manually-created 30 seconds video with activity between
15 and 20 seconds.

Relatively quick!

test/test_feature_extractors_functional.py

@@ -0,0 +1,44 @@
+"""test_feature_extractors_functional.py -- functional tests for feature extractors
+
+This module contains functional tests for FEs using crafted and/or generated media files
+to verify that the FEs are working as expected:
+
+ - laughter detection -- uses videos with laughs at known times
+ - video activity -- uses videos with visual activity at known times
+ - audio loudness -- uses videos with audio at known times
+
+etc.
+
+These tests are marked slow to avoid running them during normal test runs.
+"""
+
+import unittest
+import pipeline.feature_extractors as extractors
+import test.mocks as mocks
+class TestVideoActivityFEFunctional(unittest.TestCase):
+    """TestVisualActivityFEFunctional -- functional tests for visual activity feature extractor
+    """
+
+    def test_visual_activity_functional(self):
+        """Test visual activity feature extractor
+
+        use:
+         - sample_videos/sample-manual-visualactivity.mp4 :: activity at 15-20s -- pass if activity detected anywhere in this range
+        """
+        SAMPLE_VIDEO = "/home/robert/code/softdev2023-24/summerproject/highlights/test/sample_videos/sample-manual-visualactivity.mp4"
+
+        START_TIME = 15
+        END_TIME = 20
+        # create mock source with the video
+        source = mocks.MockSource(path=SAMPLE_VIDEO)
+
+        # create the feature extractor
+        testfe = extractors.VideoActivityFeatureExtractor(input_files=[source])
+        testfe.setup()
+        testfe.run()
+        testfe.teardown()
+
+        # check if the feature was extracted:
+        self.assertTrue(testfe.features)
+        # check if the feature interval is within the expected range
+        self.assertTrue(testfe.features[0].interval.start >= START_TIME)