test: add TestLaughterFEFunctional

Uses a manually-crafted video with laughters between 15-20s.

Test takes LaughFE's internal Feature time adjustment into account (see related
commit).

Note: very slow test

@see: df3c559

test/test_feature_extractors_functional.py

@@ -21,6 +21,41 @@ class FEFunctionalTest(unittest.TestCase):
     """
     SAMPLE_DIR = "/home/robert/code/softdev2023-24/summerproject/highlights/test/sample_videos"
 
+
+class TestLaughterFEFunctional(FEFunctionalTest):
+    """TestLaughterFEFunctional -- functional tests for laughter detection feature extractor"""
+
+    def test_laughter_detection(self):
+        """Test laughter detection feature extractor
+
+        Uses:
+            - sample_videos/sample-manual-audio-laughs-video-colours.mp4
+              :: laughters at 15-20s
+                 -- pass iff laughter features extracted in this range, *but*
+                    NOTE: LaughFE subtracts from start time to capture what preceded the laughter
+                    so we need to subtract this time (and adds a little after too)
+                    FE 'exposes' these as _PREPEND_TIME and _APPEND_TIME
+        """
+        SAMPLE_VIDEO = f"{self.SAMPLE_DIR}/sample-manual-audio-laughs-video-colours.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.LaughterFeatureExtractor(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 - testfe._PREPEND_TIME))
+        self.assertTrue(testfe.features[0].interval.end <= (END_TIME + testfe._APPEND_TIME))
+
+
 class TestVideoActivityFEFunctional(FEFunctionalTest):
     """TestVisualActivityFEFunctional -- functional tests for visual activity feature extractor
     """