'Test that only one filename starts with 000.'

def test_static_content_write_js(self):

    output_root = path(u'common/static/xmodule/descriptors/js')
    js_file_paths = _write_js(output_root, _list_descriptors())
    js_file_paths = [file_path for file_path in js_file_paths if os.path.basename(file_path).startswith('000-')]
    self.assertEqual(len(js_file_paths), 1)
    self.assertIn('XModule.Descriptor    =    (function()    {', open(js_file_paths[0]).read())
