Add server name check for multiple creations

As https://developer.openstack.org/api-ref/compute/#create-multiple-servers
the server names become {name}-1, {name}-2, {name}-3 by default.
Then this patch adds the corresponding check on Tempest.
NOTE: This comes from a review If5369bcf4a6f7fc36190e153776e60446eb14040

Change-Id: I2b544d4ccb54cb5e6db71f788926ac13be7a4fe0
diff --git a/tempest/api/compute/servers/test_multiple_create.py b/tempest/api/compute/servers/test_multiple_create.py
index 059454d..b75306e 100644
--- a/tempest/api/compute/servers/test_multiple_create.py
+++ b/tempest/api/compute/servers/test_multiple_create.py
@@ -23,18 +23,24 @@
     @decorators.idempotent_id('61e03386-89c3-449c-9bb1-a06f423fd9d1')
     def test_multiple_create(self):
         tenant_network = self.get_tenant_network()
+        server_names = set()
         body, servers = compute.create_test_server(
             self.os_primary,
+            name='VM',
             wait_until='ACTIVE',
             min_count=2,
             tenant_network=tenant_network)
         for server in servers:
             self.addCleanup(self.servers_client.delete_server, server['id'])
+            server_names.add(server['name'])
         # NOTE(maurosr): do status response check and also make sure that
         # reservation_id is not in the response body when the request send
         # contains return_reservation_id=False
         self.assertNotIn('reservation_id', body)
         self.assertEqual(2, len(servers))
+        # NOTE: If specifying a server name on the request API,
+        # server names should be "(name)-(index)" on Nova API side.
+        self.assertEqual(set(['VM-1', 'VM-2']), server_names)
 
     @decorators.idempotent_id('864777fb-2f1e-44e3-b5b9-3eb6fa84f2f7')
     def test_multiple_create_with_reservation_return(self):