diff --git a/test/test_grpc_models_accessor.py b/test/test_grpc_models_accessor.py
index 707b5ef..03e9285 100644
--- a/test/test_grpc_models_accessor.py
+++ b/test/test_grpc_models_accessor.py
@@ -31,7 +31,7 @@
         }
         with self.assertRaises(Exception) as e:
             GRPCModelsAccessor.get_model_from_classname('i-do-not-exists', data)
-        self.assertEqual(e.exception.message, "[XOS-TOSCA] The model your tring to create (name: test, class: i-do-not-exists) is not know by xos-core")
+        self.assertEqual(e.exception.message, "[XOS-TOSCA] The model you are trying to create (name: test, class: i-do-not-exists) is not know by xos-core")
 
     @patch.object(FakeResource.objects, "filter")
     @patch.object(FakeResource.objects, "new", MagicMock(return_value=FakeModel))
diff --git a/test/test_tosca_parser_e2e.py b/test/test_tosca_parser_e2e.py
index 78276f2..5438c76 100644
--- a/test/test_tosca_parser_e2e.py
+++ b/test/test_tosca_parser_e2e.py
@@ -130,4 +130,37 @@
 
         saved_user = parser.saved_model_by_name['user_test']
         self.assertEqual(saved_user.firstname, 'User')
-        self.assertEqual(saved_user.site_id, 1)
\ No newline at end of file
+        self.assertEqual(saved_user.site_id, 1)
+
+    @patch.dict(RESOURCES, mock_resources, clear=True)
+    @patch.object(FakeSite.objects, 'filter', MagicMock(return_value=[]))
+    def test_must_exist_fail(self):
+        """
+        [TOSCA_Parser] Should throw an error if an object with 'must_exist' does not exist
+        """
+        recipe = """
+        tosca_definitions_version: tosca_simple_yaml_1_0
+
+        description: Create a new site with one user
+
+        imports:
+           - custom_types/user.yaml
+           - custom_types/site.yaml
+
+        topology_template:
+          node_templates:
+
+            # Site
+            site_onlab:
+              type: tosca.nodes.Site
+              properties:
+                name: Open Networking Lab
+                must-exist: True
+        """
+
+        parser = TOSCA_Parser(recipe)
+
+        with self.assertRaises(Exception) as e:
+            parser.execute()
+
+        self.assertEqual(e.exception.message, "[XOS-TOSCA] Model Site:Open Networking Lab has property 'must-exist' but cannot be found")
diff --git a/test/tosca/must_exist.yaml b/test/tosca/must_exist.yaml
new file mode 100644
index 0000000..a6a720c
--- /dev/null
+++ b/test/tosca/must_exist.yaml
@@ -0,0 +1,33 @@
+tosca_definitions_version: tosca_simple_yaml_1_0
+
+description: Persist xos-sample-gui-extension
+
+imports:
+   - custom_types/user.yaml
+   - custom_types/site.yaml
+   - custom_types/xosguiextension.yaml
+
+topology_template:
+  node_templates:
+
+    # Site
+    site_onlab:
+      type: tosca.nodes.Site
+      properties:
+        name: Open Networking Lab
+        must-exist: True
+
+    # User
+    user_test:
+      type: tosca.nodes.User
+      properties:
+        username: test@opencord.org
+        email: test@opencord.org
+        password: mypwd
+        firstname: User
+        lastname: Test
+        is_admin: True
+      requirements:
+        - site:
+            node: site_onlab
+            relationship: tosca.relationships.BelongsToOne
\ No newline at end of file