diff --git a/patrole_tempest_plugin/tests/unit/fixtures.py b/patrole_tempest_plugin/tests/unit/fixtures.py
index f25e05d..ed50e15 100644
--- a/patrole_tempest_plugin/tests/unit/fixtures.py
+++ b/patrole_tempest_plugin/tests/unit/fixtures.py
@@ -53,15 +53,11 @@
 
 
 class RbacUtilsFixture(fixtures.Fixture):
-    """Fixture for RbacUtils class."""
+    """Fixture for `RbacUtils` class."""
 
     USER_ID = mock.sentinel.user_id
     PROJECT_ID = mock.sentinel.project_id
 
-    def __init__(self, **kwargs):
-        super(RbacUtilsFixture, self).__init__()
-        self.available_roles = None
-
     def setUp(self):
         super(RbacUtilsFixture, self).setUp()
 
@@ -81,29 +77,54 @@
         self.roles_v3_client = (
             self.mock_test_obj.get_client_manager.return_value.roles_v3_client)
 
+        self.set_roles(['admin', 'member'], [])
+
     def switch_role(self, *role_toggles):
         """Instantiate `rbac_utils.RbacUtils` and call `switch_role`.
 
         Create an instance of `rbac_utils.RbacUtils` and call `switch_role`
         for each boolean value in `role_toggles`. The number of calls to
-        `switch_role` is always 1 + len(role_toggles) because the
+        `switch_role` is always 1 + len(`role_toggles`) because the
         `rbac_utils.RbacUtils` constructor automatically calls `switch_role`.
 
         :param role_toggles: the list of boolean values iterated over and
             passed to `switch_role`.
         """
-        if not self.available_roles:
-            self.set_roles('admin', 'member')
-
         self.fake_rbac_utils = rbac_utils.RbacUtils(self.mock_test_obj)
+
         for role_toggle in role_toggles:
             self.fake_rbac_utils.switch_role(self.mock_test_obj, role_toggle)
+            # NOTE(felipemonteiro): Simulate that a role switch has occurred
+            # by updating the user's current role to the new role. This means
+            # that all API actions involved during a role switch -- listing,
+            # deleting and adding roles -- are executed, making it easier to
+            # assert that mock calls were called as expected.
+            new_role = 'member' if role_toggle else 'admin'
+            self.set_roles(['admin', 'member'], [new_role])
 
-    def set_roles(self, *roles):
-        """Set the list of available roles in the system to `roles`."""
-        self.available_roles = {
+    def set_roles(self, roles, roles_on_project=None):
+        """Set the list of available roles in the system.
+
+        :param roles: List of roles returned by ``list_roles``.
+        :param roles_on_project: List of roles returned by
+            ``list_user_roles_on_project``.
+        :returns: None.
+        """
+        if not roles_on_project:
+            roles_on_project = []
+        if not isinstance(roles, list):
+            roles = [roles]
+        if not isinstance(roles_on_project, list):
+            roles_on_project = [roles_on_project]
+
+        available_roles = {
             'roles': [{'name': role, 'id': '%s_id' % role} for role in roles]
         }
-        self.roles_v3_client.list_user_roles_on_project.return_value =\
-            self.available_roles
-        self.roles_v3_client.list_roles.return_value = self.available_roles
+        available_project_roles = {
+            'roles': [{'name': role, 'id': '%s_id' % role}
+                      for role in roles_on_project]
+        }
+
+        self.roles_v3_client.list_roles.return_value = available_roles
+        self.roles_v3_client.list_user_roles_on_project.return_value = (
+            available_project_roles)
diff --git a/patrole_tempest_plugin/tests/unit/test_rbac_utils.py b/patrole_tempest_plugin/tests/unit/test_rbac_utils.py
index 79503b1..540283a 100644
--- a/patrole_tempest_plugin/tests/unit/test_rbac_utils.py
+++ b/patrole_tempest_plugin/tests/unit/test_rbac_utils.py
@@ -34,17 +34,19 @@
 
     def test_switch_role_with_missing_admin_role(self):
         self.rbac_utils.set_roles('member')
-        e = self.assertRaises(rbac_exceptions.RbacResourceSetupFailed,
-                              self.rbac_utils.switch_role, True)
-        self.assertIn("Role with name 'admin' does not exist in the system.",
-                      e.__str__())
+        error_re = (
+            'Roles defined by `\[rbac\] rbac_test_role` and `\[identity\] '
+            'admin_role` must be defined in the system.')
+        self.assertRaisesRegex(rbac_exceptions.RbacResourceSetupFailed,
+                               error_re, self.rbac_utils.switch_role)
 
     def test_switch_role_with_missing_rbac_role(self):
         self.rbac_utils.set_roles('admin')
-        e = self.assertRaises(rbac_exceptions.RbacResourceSetupFailed,
-                              self.rbac_utils.switch_role, True)
-        self.assertIn("Role defined by rbac_test_role does not exist in the "
-                      "system.", e.__str__())
+        error_re = (
+            'Roles defined by `\[rbac\] rbac_test_role` and `\[identity\] '
+            'admin_role` must be defined in the system.')
+        self.assertRaisesRegex(rbac_exceptions.RbacResourceSetupFailed,
+                               error_re, self.rbac_utils.switch_role)
 
     def test_switch_role_to_admin_role(self):
         self.rbac_utils.switch_role()
@@ -61,6 +63,16 @@
             .assert_called_once_with()
         mock_time.sleep.assert_called_once_with(1)
 
+    def test_switch_role_to_admin_role_avoids_role_switch(self):
+        self.rbac_utils.set_roles(['admin', 'member'], 'admin')
+        self.rbac_utils.switch_role()
+
+        roles_client = self.rbac_utils.roles_v3_client
+        mock_time = self.rbac_utils.mock_time
+
+        roles_client.create_user_role_on_project.assert_not_called()
+        mock_time.sleep.assert_not_called()
+
     def test_switch_role_to_member_role(self):
         self.rbac_utils.switch_role(True)
 
@@ -80,6 +92,19 @@
             [mock.call()] * 2)
         mock_time.sleep.assert_has_calls([mock.call(1)] * 2)
 
+    def test_switch_role_to_member_role_avoids_role_switch(self):
+        self.rbac_utils.set_roles(['admin', 'member'], 'member')
+        self.rbac_utils.switch_role(True)
+
+        roles_client = self.rbac_utils.roles_v3_client
+        mock_time = self.rbac_utils.mock_time
+
+        roles_client.create_user_role_on_project.assert_has_calls([
+            mock.call(self.rbac_utils.PROJECT_ID, self.rbac_utils.USER_ID,
+                      'admin_id')
+        ])
+        mock_time.sleep.assert_called_once_with(1)
+
     def test_switch_role_to_member_role_then_admin_role(self):
         self.rbac_utils.switch_role(True, False)
 
@@ -137,19 +162,22 @@
         self.assertIn(expected_error_message, str(e))
 
     def test_clear_user_roles(self):
-        self.rbac_utils.switch_role(True)
+        # NOTE(felipemonteiro): Set the user's roles on the project to
+        # include 'random' to coerce a role switch, or else it will be
+        # skipped.
+        self.rbac_utils.set_roles(['admin', 'member'], ['member', 'random'])
+        self.rbac_utils.switch_role()
 
         roles_client = self.rbac_utils.roles_v3_client
 
-        roles_client.list_user_roles_on_project.assert_has_calls([
-            mock.call(self.rbac_utils.PROJECT_ID, self.rbac_utils.USER_ID)
-        ] * 2)
+        roles_client.list_user_roles_on_project.assert_called_once_with(
+            self.rbac_utils.PROJECT_ID, self.rbac_utils.USER_ID)
         roles_client.delete_role_from_user_on_project.\
             assert_has_calls([
                 mock.call(mock.sentinel.project_id, mock.sentinel.user_id,
-                          'admin_id'),
+                          'member_id'),
                 mock.call(mock.sentinel.project_id, mock.sentinel.user_id,
-                          'member_id')] * 2)
+                          'random_id')])
 
     @mock.patch.object(rbac_utils, 'LOG', autospec=True)
     @mock.patch.object(rbac_utils, 'sys', autospec=True)