Add unit test zone migration with_attached_volume

Add a test for the zone migration strategy using the
with_attached_volume parameter, setting storage_pools but not
compute_nodes. With volumes attached to instances, with these inputs,
the strategy should propose an action plan to migrate volumes and the
instances they are attached to, since Nova, even without the user
passing a destination node for the instances is able to find one.
However, the execution results in an error, since the strategy assumes
that the compute_nodes dict will always be there.

Change-Id: Ifac28b1aab8a0caf77d97e4c19d051e764256674

watcher/tests/decision_engine/strategy/strategies/test_zone_migration.py

@@ -79,6 +79,13 @@ class TestZoneMigration(TestBaseStrategy):
         self.m_priority = p_priority.start()
         self.addCleanup(p_priority.stop)
 
+        p_with_attached_volume = mock.patch.object(
+            strategies.ZoneMigration, "with_attached_volume",
+            new_callable=mock.PropertyMock
+        )
+        self.m_with_attached_volume = p_with_attached_volume.start()
+        self.addCleanup(p_with_attached_volume.stop)
+
         model = self.fake_c_cluster.generate_scenario_1()
         self.m_c_model.return_value = model
 
@@ -99,6 +106,7 @@ class TestZoneMigration(TestBaseStrategy):
             {"src_pool": "src2@back1#pool1", "dst_pool": "dst2@back2#pool1",
              "src_type": "type2", "dst_type": "type3"}
         ]
+        self.m_with_attached_volume.return_value = False
 
         self.strategy = strategies.ZoneMigration(
             config=mock.Mock())
@@ -154,6 +162,7 @@ class TestZoneMigration(TestBaseStrategy):
         setattr(volume, 'size', kwargs.get('size', '1'))
         setattr(volume, 'created_at',
                 kwargs.get('created_at', '1977-01-01T00:00:00'))
+        setattr(volume, 'attachments', kwargs.get('attachments', []))
         volume.volume_type = kwargs.get('volume_type', 'type1')
 
         return volume
@@ -322,6 +331,39 @@ class TestZoneMigration(TestBaseStrategy):
         # followup
         self.assertIsNone(migration_params['destination_node'])
 
+    def test_execute_migrate_volume_no_compute_nodes(self):
+        instance_on_src1 = self.fake_instance(
+            host="src1",
+            id="INSTANCE_1",
+            name="INSTANCE_1")
+        vol_attach = [{"server_id": instance_on_src1.id}]
+        volume_on_src1 = self.fake_volume(host="src1@back1#pool1",
+                                          id=volume_uuid_mapping["volume_1"],
+                                          name="volume_1",
+                                          status="in-use",
+                                          attachments=vol_attach)
+        self.m_c_helper.get_volume_list.return_value = [
+            volume_on_src1,
+            ]
+        self.m_migrate_storage_pools.return_value = [
+            {"src_pool": "src1@back1#pool1",
+             "dst_pool": "dst1@back1#pool1",
+             "src_type": "type1", "dst_type": "type1"},
+            ]
+        self.m_migrate_compute_nodes.return_value = None
+        self.m_n_helper.get_instance_list.return_value = [
+            instance_on_src1,
+        ]
+        self.m_with_attached_volume.return_value = True
+
+        # check that the solution contains one 'swap' volume migration and one
+        # instance migration, once the bug is fixed
+        # solution = self.strategy.execute()
+
+        # temporarily catch the error to demonstrate it
+        exception = self.assertRaises(TypeError, self.strategy.execute)
+        self.assertEqual(str(exception), "'NoneType' object is not iterable")
+
     def test_execute_retype_volume(self):
         volume_on_src2 = self.fake_volume(host="src2@back1#pool1",
                                           id=volume_uuid_mapping["volume_2"],