diff --git a/tempest/api/object_storage/base.py b/tempest/api/object_storage/base.py
index 6b18182..ccc0067 100644
--- a/tempest/api/object_storage/base.py
+++ b/tempest/api/object_storage/base.py
@@ -44,9 +44,6 @@
                 cls.isolated_creds.get_admin_creds())
             # Get isolated creds for alt user
             cls.os_alt = clients.Manager(cls.isolated_creds.get_alt_creds())
-            # Add isolated users to operator role so that they can create a
-            # container in swift.
-            cls._assign_member_role()
         else:
             cls.os = clients.Manager()
             cls.os_admin = clients.AdminManager()
@@ -80,22 +77,6 @@
         super(BaseObjectTest, cls).tearDownClass()
 
     @classmethod
-    def _assign_member_role(cls):
-        primary_creds = cls.isolated_creds.get_primary_creds()
-        alt_creds = cls.isolated_creds.get_alt_creds()
-        swift_role = CONF.object_storage.operator_role
-        try:
-            resp, roles = cls.os_admin.identity_client.list_roles()
-            role = next(r for r in roles if r['name'] == swift_role)
-        except StopIteration:
-            msg = "No role named %s found" % swift_role
-            raise exceptions.NotFound(msg)
-        for creds in [primary_creds, alt_creds]:
-            cls.os_admin.identity_client.assign_user_role(creds.tenant_id,
-                                                          creds.user_id,
-                                                          role['id'])
-
-    @classmethod
     def delete_containers(cls, containers, container_client=None,
                           object_client=None):
         """Remove given containers and all objects in them.
diff --git a/tempest/common/isolated_creds.py b/tempest/common/isolated_creds.py
index b4618ed..8166de5 100644
--- a/tempest/common/isolated_creds.py
+++ b/tempest/common/isolated_creds.py
@@ -106,12 +106,23 @@
             roles = self.identity_admin_client.roles.list()
         return roles
 
-    def _assign_user_role(self, tenant, user, role):
+    def _assign_user_role(self, tenant, user, role_name):
+        role = None
+        try:
+            roles = self._list_roles()
+            if self.tempest_client:
+                role = next(r for r in roles if r['name'] == role_name)
+            else:
+                role = next(r for r in roles if r.name == role_name)
+        except StopIteration:
+            msg = 'No "%s" role found' % role_name
+            raise exceptions.NotFound(msg)
         if self.tempest_client:
-            self.identity_admin_client.assign_user_role(tenant, user, role)
+            self.identity_admin_client.assign_user_role(tenant['id'],
+                                                        user['id'], role['id'])
         else:
-            self.identity_admin_client.roles.add_user_role(user,
-                                                           role, tenant=tenant)
+            self.identity_admin_client.roles.add_user_role(user.id, role.id,
+                                                           tenant.id)
 
     def _delete_user(self, user):
         if self.tempest_client:
@@ -149,22 +160,11 @@
         email = data_utils.rand_name(root) + suffix + "@example.com"
         user = self._create_user(username, self.password,
                                  tenant, email)
+        # NOTE(andrey-mp): user needs this role to create containers in swift
+        swift_operator_role = CONF.object_storage.operator_role
+        self._assign_user_role(tenant, user, swift_operator_role)
         if admin:
-            role = None
-            try:
-                roles = self._list_roles()
-                admin_role = CONF.identity.admin_role
-                if self.tempest_client:
-                    role = next(r for r in roles if r['name'] == admin_role)
-                else:
-                    role = next(r for r in roles if r.name == admin_role)
-            except StopIteration:
-                msg = "No admin role found"
-                raise exceptions.NotFound(msg)
-            if self.tempest_client:
-                self._assign_user_role(tenant['id'], user['id'], role['id'])
-            else:
-                self._assign_user_role(tenant.id, user.id, role.id)
+            self._assign_user_role(tenant, user, CONF.identity.admin_role)
         return self._get_credentials(user, tenant)
 
     def _get_credentials(self, user, tenant):
diff --git a/tempest/tests/test_tenant_isolation.py b/tempest/tests/test_tenant_isolation.py
index 485beff..bbc3d15 100644
--- a/tempest/tests/test_tenant_isolation.py
+++ b/tempest/tests/test_tenant_isolation.py
@@ -42,6 +42,8 @@
         self.fake_http = fake_http.fake_httplib2(return_type=200)
         self.stubs.Set(http.ClosingHttp, 'request',
                        fake_identity._fake_v2_response)
+        cfg.CONF.set_default('operator_role', 'FakeRole',
+                             group='object-storage')
 
     def test_tempest_client(self):
         iso_creds = isolated_creds.IsolatedCreds('test class')
@@ -92,6 +94,31 @@
                           {'id': id, 'name': name})))
         return tenant_fix
 
+    def _mock_list_roles(self, id, name):
+        roles_fix = self.useFixture(mockpatch.PatchObject(
+            json_iden_client.IdentityClientJSON,
+            'list_roles',
+            return_value=({'status': 200},
+                          [{'id': id, 'name': name},
+                           {'id': '1', 'name': 'FakeRole'}])))
+        return roles_fix
+
+    def _mock_assign_user_role(self):
+        tenant_fix = self.useFixture(mockpatch.PatchObject(
+            json_iden_client.IdentityClientJSON,
+            'assign_user_role',
+            return_value=({'status': 200},
+                          {})))
+        return tenant_fix
+
+    def _mock_list_role(self):
+        roles_fix = self.useFixture(mockpatch.PatchObject(
+            json_iden_client.IdentityClientJSON,
+            'list_roles',
+            return_value=({'status': 200},
+                          [{'id': '1', 'name': 'FakeRole'}])))
+        return roles_fix
+
     def _mock_network_create(self, iso_creds, id, name):
         net_fix = self.useFixture(mockpatch.PatchObject(
             iso_creds.network_admin_client,
@@ -121,6 +148,8 @@
         cfg.CONF.set_default('neutron', False, 'service_available')
         iso_creds = isolated_creds.IsolatedCreds('test class',
                                                  password='fake_password')
+        self._mock_assign_user_role()
+        self._mock_list_role()
         self._mock_tenant_create('1234', 'fake_prim_tenant')
         self._mock_user_create('1234', 'fake_prim_user')
         primary_creds = iso_creds.get_primary_creds()
@@ -135,13 +164,9 @@
         cfg.CONF.set_default('neutron', False, 'service_available')
         iso_creds = isolated_creds.IsolatedCreds('test class',
                                                  password='fake_password')
+        self._mock_list_roles('1234', 'admin')
         self._mock_user_create('1234', 'fake_admin_user')
         self._mock_tenant_create('1234', 'fake_admin_tenant')
-        self.useFixture(mockpatch.PatchObject(
-            json_iden_client.IdentityClientJSON,
-            'list_roles',
-            return_value=({'status': 200},
-                          [{'id': '1234', 'name': 'admin'}])))
 
         user_mock = mock.patch.object(json_iden_client.IdentityClientJSON,
                                       'assign_user_role')
@@ -150,7 +175,9 @@
         with mock.patch.object(json_iden_client.IdentityClientJSON,
                                'assign_user_role') as user_mock:
             admin_creds = iso_creds.get_admin_creds()
-        user_mock.assert_called_once_with('1234', '1234', '1234')
+        user_mock.assert_has_calls([
+            mock.call('1234', '1234', '1'),
+            mock.call('1234', '1234', '1234')])
         self.assertEqual(admin_creds.username, 'fake_admin_user')
         self.assertEqual(admin_creds.tenant_name, 'fake_admin_tenant')
         # Verify IDs
@@ -162,6 +189,8 @@
         cfg.CONF.set_default('neutron', False, 'service_available')
         iso_creds = isolated_creds.IsolatedCreds('test class',
                                                  password='fake_password')
+        self._mock_assign_user_role()
+        roles_fix = self._mock_list_role()
         tenant_fix = self._mock_tenant_create('1234', 'fake_prim_tenant')
         user_fix = self._mock_user_create('1234', 'fake_prim_user')
         iso_creds.get_primary_creds()
@@ -172,16 +201,11 @@
         iso_creds.get_alt_creds()
         tenant_fix.cleanUp()
         user_fix.cleanUp()
+        roles_fix.cleanUp()
         tenant_fix = self._mock_tenant_create('123456', 'fake_admin_tenant')
         user_fix = self._mock_user_create('123456', 'fake_admin_user')
-        self.useFixture(mockpatch.PatchObject(
-            json_iden_client.IdentityClientJSON,
-            'list_roles',
-            return_value=({'status': 200},
-                          [{'id': '123456', 'name': 'admin'}])))
-        with mock.patch.object(json_iden_client.IdentityClientJSON,
-                               'assign_user_role'):
-            iso_creds.get_admin_creds()
+        self._mock_list_roles('123456', 'admin')
+        iso_creds.get_admin_creds()
         user_mock = self.patch(
             'tempest.services.identity.json.identity_client.'
             'IdentityClientJSON.delete_user')
@@ -209,6 +233,8 @@
         cfg.CONF.set_default('neutron', False, 'service_available')
         iso_creds = isolated_creds.IsolatedCreds('test class',
                                                  password='fake_password')
+        self._mock_assign_user_role()
+        self._mock_list_role()
         self._mock_user_create('1234', 'fake_alt_user')
         self._mock_tenant_create('1234', 'fake_alt_tenant')
         alt_creds = iso_creds.get_alt_creds()
@@ -222,6 +248,8 @@
     def test_network_creation(self, MockRestClient):
         iso_creds = isolated_creds.IsolatedCreds('test class',
                                                  password='fake_password')
+        self._mock_assign_user_role()
+        self._mock_list_role()
         self._mock_user_create('1234', 'fake_prim_user')
         self._mock_tenant_create('1234', 'fake_prim_tenant')
         self._mock_network_create(iso_creds, '1234', 'fake_net')
@@ -247,6 +275,8 @@
         iso_creds = isolated_creds.IsolatedCreds('test class',
                                                  password='fake_password')
         # Create primary tenant and network
+        self._mock_assign_user_role()
+        roles_fix = self._mock_list_role()
         user_fix = self._mock_user_create('1234', 'fake_prim_user')
         tenant_fix = self._mock_tenant_create('1234', 'fake_prim_tenant')
         net_fix = self._mock_network_create(iso_creds, '1234', 'fake_net')
@@ -278,6 +308,7 @@
         net_fix.cleanUp()
         subnet_fix.cleanUp()
         router_fix.cleanUp()
+        roles_fix.cleanUp()
         # Create admin tenant and networks
         user_fix = self._mock_user_create('123456', 'fake_admin_user')
         tenant_fix = self._mock_tenant_create('123456', 'fake_admin_tenant')
@@ -286,14 +317,8 @@
         subnet_fix = self._mock_subnet_create(iso_creds, '123456',
                                               'fake_admin_subnet')
         router_fix = self._mock_router_create('123456', 'fake_admin_router')
-        self.useFixture(mockpatch.PatchObject(
-            json_iden_client.IdentityClientJSON,
-            'list_roles',
-            return_value=({'status': 200},
-                          [{'id': '123456', 'name': 'admin'}])))
-        with mock.patch.object(json_iden_client.IdentityClientJSON,
-                               'assign_user_role'):
-            iso_creds.get_admin_creds()
+        self._mock_list_roles('123456', 'admin')
+        iso_creds.get_admin_creds()
         self.patch('tempest.services.identity.json.identity_client.'
                    'IdentityClientJSON.delete_user')
         self.patch('tempest.services.identity.json.identity_client.'
@@ -348,6 +373,8 @@
     def test_network_alt_creation(self, MockRestClient):
         iso_creds = isolated_creds.IsolatedCreds('test class',
                                                  password='fake_password')
+        self._mock_assign_user_role()
+        self._mock_list_role()
         self._mock_user_create('1234', 'fake_alt_user')
         self._mock_tenant_create('1234', 'fake_alt_tenant')
         self._mock_network_create(iso_creds, '1234', 'fake_alt_net')
@@ -372,6 +399,7 @@
     def test_network_admin_creation(self, MockRestClient):
         iso_creds = isolated_creds.IsolatedCreds('test class',
                                                  password='fake_password')
+        self._mock_assign_user_role()
         self._mock_user_create('1234', 'fake_admin_user')
         self._mock_tenant_create('1234', 'fake_admin_tenant')
         self._mock_network_create(iso_creds, '1234', 'fake_admin_net')
@@ -380,14 +408,8 @@
         router_interface_mock = self.patch(
             'tempest.services.network.json.network_client.NetworkClientJSON.'
             'add_router_interface_with_subnet_id')
-        self.useFixture(mockpatch.PatchObject(
-            json_iden_client.IdentityClientJSON,
-            'list_roles',
-            return_value=({'status': 200},
-                          [{'id': '123456', 'name': 'admin'}])))
-        with mock.patch.object(json_iden_client.IdentityClientJSON,
-                               'assign_user_role'):
-            iso_creds.get_admin_creds()
+        self._mock_list_roles('123456', 'admin')
+        iso_creds.get_admin_creds()
         router_interface_mock.called_once_with('1234', '1234')
         network = iso_creds.get_admin_network()
         subnet = iso_creds.get_admin_subnet()
@@ -410,6 +432,8 @@
         iso_creds = isolated_creds.IsolatedCreds('test class',
                                                  password='fake_password',
                                                  network_resources=net_dict)
+        self._mock_assign_user_role()
+        self._mock_list_role()
         self._mock_user_create('1234', 'fake_prim_user')
         self._mock_tenant_create('1234', 'fake_prim_tenant')
         net = mock.patch.object(iso_creds.network_admin_client,
@@ -444,6 +468,8 @@
         iso_creds = isolated_creds.IsolatedCreds('test class',
                                                  password='fake_password',
                                                  network_resources=net_dict)
+        self._mock_assign_user_role()
+        self._mock_list_role()
         self._mock_user_create('1234', 'fake_prim_user')
         self._mock_tenant_create('1234', 'fake_prim_tenant')
         self.assertRaises(exceptions.InvalidConfiguration,
@@ -460,6 +486,8 @@
         iso_creds = isolated_creds.IsolatedCreds('test class',
                                                  password='fake_password',
                                                  network_resources=net_dict)
+        self._mock_assign_user_role()
+        self._mock_list_role()
         self._mock_user_create('1234', 'fake_prim_user')
         self._mock_tenant_create('1234', 'fake_prim_tenant')
         self.assertRaises(exceptions.InvalidConfiguration,
@@ -476,6 +504,8 @@
         iso_creds = isolated_creds.IsolatedCreds('test class',
                                                  password='fake_password',
                                                  network_resources=net_dict)
+        self._mock_assign_user_role()
+        self._mock_list_role()
         self._mock_user_create('1234', 'fake_prim_user')
         self._mock_tenant_create('1234', 'fake_prim_tenant')
         self.assertRaises(exceptions.InvalidConfiguration,