def METHOD_NAME(self):
    """Checks the duration when mixing an echo longer than the capture."""
    mix_filepath = input_mixer.ApmInputMixer.Mix(
        self._tmp_path, self._audio_tracks['capture']['filepath'],
        self._audio_tracks['longer']['filepath'])
    self.assertTrue(os.path.exists(mix_filepath))
    mix = signal_processing.SignalProcessingUtils.LoadWav(mix_filepath)
    self.assertEqual(
        self._audio_tracks['capture']['num_samples'],
        signal_processing.SignalProcessingUtils.CountSamples(mix))