Ensure required flavor and image are configured

Change-Id: I2a2f3fbf0c523e294dd52024a2f55c0ad158b15b
diff --git a/heat_tempest_plugin/tests/scenario/test_octavia_lbaas.py b/heat_tempest_plugin/tests/scenario/test_octavia_lbaas.py
index ce07262..46781d0 100644
--- a/heat_tempest_plugin/tests/scenario/test_octavia_lbaas.py
+++ b/heat_tempest_plugin/tests/scenario/test_octavia_lbaas.py
@@ -23,6 +23,10 @@
         self.template_name = 'octavia_lbaas.yaml'
         self.member_template_name = 'lb_member.yaml'
         self.sub_dir = 'templates'
+        if not self.conf.minimal_image_ref:
+            raise self.skipException("No minimal image configured to test")
+        if not self.conf.minimal_instance_type:
+            raise self.skipException("No minimal flavor configured to test")
 
     def _create_stack(self):
         self.parameters = {
diff --git a/heat_tempest_plugin/tests/scenario/test_server_signal.py b/heat_tempest_plugin/tests/scenario/test_server_signal.py
index 167dfa0..c4deb3c 100644
--- a/heat_tempest_plugin/tests/scenario/test_server_signal.py
+++ b/heat_tempest_plugin/tests/scenario/test_server_signal.py
@@ -81,6 +81,10 @@
 
     @decorators.idempotent_id('8da0f6cc-60e6-4298-9e54-e1f905c5552a')
     def test_server_signal_userdata_format_raw(self):
+        if not self.conf.minimal_image_ref:
+            raise self.skipException("No minimal image configured to test")
+        if not self.conf.minimal_instance_type:
+            raise self.skipException("No minimal flavor configured to test")
         self._test_server_signal(image=self.conf.minimal_image_ref,
                                  flavor=self.conf.minimal_instance_type)
 
@@ -88,6 +92,8 @@
     def test_server_signal_userdata_format_software_config(self):
         if not self.conf.image_ref:
             raise self.skipException("No image configured to test")
+        if not self.conf.instance_type:
+            raise self.skipException("No flavor configured to test")
         self._test_server_signal(user_data_format='SOFTWARE_CONFIG',
                                  image=self.conf.image_ref,
                                  flavor=self.conf.instance_type)