Add failing test

Author: alanpoulain

features/graphql/mutation.feature

@@ -142,7 +142,7 @@ Feature: GraphQL mutation support
 
   @createSchema
   Scenario: Modify an item through a mutation
-    Given there are 1 dummy objects
+    Given there are 1 dummy objects having each 2 relatedDummies
     When I send the following GraphQL request:
     """
     mutation {
@@ -151,6 +151,13 @@ Feature: GraphQL mutation support
         name
         description
         dummyDate
+        relatedDummies {
+          edges {
+            node {
+              name
+            }
+          }
+        }
         clientMutationId
       }
     }
@@ -162,6 +169,7 @@ Feature: GraphQL mutation support
     And the JSON node "data.updateDummy.name" should be equal to "Dummy #1"
     And the JSON node "data.updateDummy.description" should be equal to "Modified description."
     And the JSON node "data.updateDummy.dummyDate" should be equal to "2018-06-05T00:00:00+00:00"
+    And the JSON node "data.updateDummy.relatedDummies.edges[0].node.name" should be equal to "RelatedDummy11"
     And the JSON node "data.updateDummy.clientMutationId" should be equal to "myId"
 
   Scenario: Modify an item with composite identifiers through a mutation