Do not pass both port-id and fixed-ip to create server

Nova doesn't allow specify port-id and fixed-ip at the same
time when create server. This patch to avoid this problem
when create internal port by subnet.

Also, this change adds integration test for create server
with subnet and fixed_ip.

Change-Id: Ib16d7f90a4eb488a853f9c2093280596fc4d783b
Partial-Bug: #1533074
diff --git a/functional/test_nova_server_networks.py b/functional/test_nova_server_networks.py
new file mode 100644
index 0000000..99311d0
--- /dev/null
+++ b/functional/test_nova_server_networks.py
@@ -0,0 +1,66 @@
+#    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 heat_integrationtests.functional import functional_base
+
+
+server_with_sub_fixed_ip_template = '''
+heat_template_version: 2016-04-08
+description: Test template to test nova server with subnet and fixed_ip.
+parameters:
+  flavor:
+    type: string
+  image:
+    type: string
+resources:
+  net:
+    type: OS::Neutron::Net
+    properties:
+      name: my_net
+  subnet:
+    type: OS::Neutron::Subnet
+    properties:
+      network: {get_resource: net}
+      cidr: 11.11.11.0/24
+  server:
+    type: OS::Nova::Server
+    properties:
+      image: {get_param: image}
+      flavor: {get_param: flavor}
+      networks:
+        - subnet: {get_resource: subnet}
+          fixed_ip: 11.11.11.11
+outputs:
+  networks:
+    value: {get_attr: [server, networks]}
+'''
+
+
+class CreateServerTest(functional_base.FunctionalTestsBase):
+
+    def setUp(self):
+        super(CreateServerTest, self).setUp()
+
+    def get_outputs(self, stack_identifier, output_key):
+        stack = self.client.stacks.get(stack_identifier)
+        output = self._stack_output(stack, output_key)
+        return output
+
+    def test_create_server_with_subnet_fixed_ip(self):
+        parms = {'flavor': self.conf.minimal_instance_type,
+                 'image': self.conf.minimal_image_ref}
+        stack_identifier = self.stack_create(
+            template=server_with_sub_fixed_ip_template,
+            stack_name='server_with_sub_ip',
+            parameters=parms)
+        networks = self.get_outputs(stack_identifier, 'networks')
+        self.assertEqual(['11.11.11.11'], networks['my_net'])