diff --git a/heat/tests/constraints/test_heat_constraints.py b/heat/tests/constraints/test_heat_constraints.py
index e962c68266..c32045aa01 100644
--- a/heat/tests/constraints/test_heat_constraints.py
+++ b/heat/tests/constraints/test_heat_constraints.py
@@ -48,7 +48,7 @@ class ResourceTypeConstraintTest(common.HeatTestCase):
 
         # Verify
         self.assertFalse(result)
-        self.assertTrue('OS::Heat::None' in self.constraint._error_message)
+        self.assertIn('OS::Heat::None', self.constraint._error_message)
         self.mock_env.get_class.assert_called_once_with(value[0])
 
     def test_validate_multiple_failures(self):
diff --git a/heat/tests/openstack/heat/test_resource_chain.py b/heat/tests/openstack/heat/test_resource_chain.py
index 504df6cc85..d1f1497a37 100644
--- a/heat/tests/openstack/heat/test_resource_chain.py
+++ b/heat/tests/openstack/heat/test_resource_chain.py
@@ -121,7 +121,7 @@ class ResourceChainTest(common.HeatTestCase):
         # No error, but no resources to create
         self.assertTrue('resources' not in tmpl)
         # Sanity check that it's actually a template
-        self.assertTrue('heat_template_version' in tmpl)
+        self.assertIn('heat_template_version', tmpl)
 
     def test_validate_nested_stack(self):
         # Test - should not raise exception
@@ -145,7 +145,7 @@ class ResourceChainTest(common.HeatTestCase):
             chain.validate_nested_stack()
             self.fail('Exception expected')
         except exception.StackValidationFailed as e:
-            self.assertTrue('unknown property group' in e.message.lower())
+            self.assertIn('unknown property group', e.message.lower())
 
     def test_validate_fake_resource_type(self):
         # Setup
@@ -161,8 +161,8 @@ class ResourceChainTest(common.HeatTestCase):
             chain.validate_nested_stack()
             self.fail('Exception expected')
         except exception.StackValidationFailed as e:
-            self.assertTrue('could not be found' in e.message.lower())
-            self.assertTrue('foo' in e.message)
+            self.assertIn('could not be found', e.message.lower())
+            self.assertIn('foo', e.message)
 
     @mock.patch.object(resource_chain.ResourceChain, 'create_with_template')
     def test_handle_create(self, mock_create):
diff --git a/heat/tests/test_signal.py b/heat/tests/test_signal.py
index 611e0bff5f..16e1a4a7db 100644
--- a/heat/tests/test_signal.py
+++ b/heat/tests/test_signal.py
@@ -206,7 +206,7 @@ class SignalTest(common.HeatTestCase):
 
         # Test
         first_url = rsrc.FnGetAtt('signal')
-        self.assertTrue('alarm_url' in first_url)
+        self.assertIn('alarm_url', first_url)
         mock_has.assert_called_once_with('signal_handler')
         mock_has.reset_mock()  # reset the count for the next check
 
@@ -355,7 +355,7 @@ class SignalTest(common.HeatTestCase):
 
         # Test
         first_url = rsrc.FnGetAtt('signal')
-        self.assertTrue('alarm_url' in first_url)
+        self.assertIn('alarm_url', first_url)
         mock_has.assert_called_once_with('signal_handler')
         mock_has.reset_mock()  # reset the count for the next check
 
diff --git a/heat_integrationtests/functional/test_env_merge.py b/heat_integrationtests/functional/test_env_merge.py
index 5e222b85f6..819770a87a 100644
--- a/heat_integrationtests/functional/test_env_merge.py
+++ b/heat_integrationtests/functional/test_env_merge.py
@@ -92,4 +92,4 @@ class EnvironmentMergingTests(functional_base.FunctionalTestsBase):
         # by checking to see that it has a value
         r3b = self.client.resources.get(stack_id, 'r3b')
         r3b_attrs = r3b.attributes
-        self.assertTrue('value' in r3b_attrs)
+        self.assertIn('value', r3b_attrs)