Update: Refactored the code

tests/test_file_manager.py

@@ -0,0 +1,33 @@
+import os
+import unittest
+
+from src.file_manager import FileManager
+
+
+class FileManagerTest(unittest.TestCase):
+    def setUp(self):
+        self.file_manager = FileManager()
+        self.dir = '<Your file directory>'  # replace with your directory
+
+    def test_download_youtube_audio(self):
+        youtube_link = '<Your YouTube link>'  # replace with a YouTube link
+        filename = f'{self.dir}/audio.mp4'
+        self.file_manager.download_youtube_audio(youtube_link, filename)
+        self.assertTrue(os.path.exists(filename))
+        os.remove(filename)  # clean up after test
+
+    def test_convert_to_wav(self):
+        mp4_file = '<Your mp4 filename>'  # replace with an MP4 file in your directory
+        wav_file = mp4_file.replace('.mp4', '.wav')
+        self.file_manager.convert_to_wav(mp4_file, wav_file)
+        self.assertTrue(os.path.exists(wav_file))
+        os.remove(wav_file)  # clean up after test
+
+    def test_load_local_file(self):
+        local_file_path = '<Your mp4 filename>'  # replace with a file in your directory
+        result_path = self.file_manager.load_local_file(local_file_path)
+        self.assertEqual(result_path, local_file_path.replace('.mp4', '.wav'))
+
+
+if __name__ == "__main__":
+    unittest.main()