🐛 fix AUTO backend support

spleeter/__main__.py

@@ -37,7 +37,7 @@ from typer import Exit, Typer
 # pylint: enable=import-error
 
 spleeter: Typer = Typer()
-""" """
+""" CLI application. """
 
 
 @spleeter.command()

spleeter/separator.py

@@ -333,6 +333,11 @@ class Separator(object):
                     (Optional) string describing the waveform (e.g. filename).
         """
         backend: str = self._params['stft_backend']
+        if backend == STFTBackend.AUTO:
+            if len(tf.config.list_physical_devices('GPU')):
+                backend = STFTBackend.TENSORFLOW
+            else:
+                backend = STFTBackend.LIBROSA
         if backend == STFTBackend.TENSORFLOW:
             return self._separate_tensorflow(waveform, audio_descriptor)
         elif backend == STFTBackend.LIBROSA:

tests/test_train.py

@@ -93,7 +93,7 @@ def test_train():
         TRAIN_CONFIG['model_dir'] = join(path, 'model')
         TRAIN_CONFIG['training_cache'] = join(path, 'cache', 'training')
         TRAIN_CONFIG['validation_cache'] = join(path, 'cache', 'validation')
-        with open('useless_config.json') as stream:
+        with open('useless_config.json', 'w') as stream:
             json.dump(TRAIN_CONFIG, stream)
         # execute training
         result = runner.invoke(spleeter, [