Add unversioned client constructor

It's a very common pattern in OpenStack to have a base level client
file that has a client constructor that takes a version as the first
parameter. This allows developers to write code that just imports the
client, rather than relying on python import paths for version
selection, which in turn allows for future version autodetection with
things like microversions.

Closes-Bug: #1514732

Change-Id: Ibf8df9c8dbdfe27d9a387304e05afe95d3e33f49

magnumclient/client.py

@@ -0,0 +1,24 @@
+# Copyright (c) 2015 IBM Corp.
+#
+# Licensed under the Apache License, Version 2.0 (the "License"); you may
+# not use this file except in compliance with the License. You may obtain
+# a copy of the License at
+#
+#      http://www.apache.org/licenses/LICENSE-2.0
+#
+# Unless required by applicable law or agreed to in writing, software
+# distributed under the License is distributed on an "AS IS" BASIS, WITHOUT
+# WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See the
+# License for the specific language governing permissions and limitations
+# under the License.
+
+from magnumclient.v1 import client
+
+
+def Client(version='1', **kwargs):
+    """Factory function to create a new container service client."""
+    if version != '1':
+        raise ValueError(
+            "magnum only has one API version. Valid values for 'version'"
+            " are '1'")
+    return client.Client(**kwargs)

magnumclient/tests/test_client.py

@@ -0,0 +1,38 @@
+# Copyright (c) 2015 IBM Corp.
+#
+# Licensed under the Apache License, Version 2.0 (the "License"); you may
+# not use this file except in compliance with the License. You may obtain
+# a copy of the License at
+#
+#      http://www.apache.org/licenses/LICENSE-2.0
+#
+# Unless required by applicable law or agreed to in writing, software
+# distributed under the License is distributed on an "AS IS" BASIS, WITHOUT
+# WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See the
+# License for the specific language governing permissions and limitations
+# under the License.
+
+import mock
+import testtools
+
+from magnumclient import client
+
+
+class ClientTest(testtools.TestCase):
+
+    @mock.patch('magnumclient.v1.client.Client')
+    def test_no_version_argument(self, mock_magnum_client):
+        client.Client(input_auth_token='mytoken', magnum_url='http://myurl/')
+        mock_magnum_client.assert_called_with(
+            input_auth_token='mytoken', magnum_url='http://myurl/')
+
+    @mock.patch('magnumclient.v1.client.Client')
+    def test_valid_version_argument(self, mock_magnum_client):
+        client.Client(version='1', magnum_url='http://myurl/')
+        mock_magnum_client.assert_called_with(magnum_url='http://myurl/')
+
+    @mock.patch('magnumclient.v1.client.Client')
+    def test_invalid_version_argument(self, mock_magnum_client):
+        self.assertRaises(
+            ValueError,
+            client.Client, version='2', magnum_url='http://myurl/')