Add client credentials flow

tests/client_credentials_tests.py

@@ -0,0 +1,27 @@
+# -*- coding: latin-1 -*-
+
+import spotipy
+from  spotipy.oauth2 import SpotifyClientCredentials
+import unittest
+
+'''
+    Client Credentials Requests Tests
+'''
+
+class ClientCredentialsTestSpotipy(unittest.TestCase):
+    '''
+        These tests require user authentication
+    '''
+
+    muse_urn = 'spotify:artist:12Chz98pHFMPJEknJQMWvI'
+
+    def test_request_with_token(self):
+        artist = spotify.artist(self.muse_urn)
+        self.assertTrue(artist['name'] == u'Muse')
+
+
+if __name__ == '__main__':
+    spotify_cc = SpotifyClientCredentials()
+    spotify = spotipy.Spotify(client_credentials_manager=spotify_cc)
+    spotify.trace = False
+    unittest.main()