test: add expectations to make sure metadata: nil isn't stored in the…

… pact (#119)

spec/features/write_pact_file_spec.rb

@@ -69,6 +69,9 @@
       expect(pact_json['interactions']).to_not include(
         include("description" => "a request for alligators")
       )
+      expect(pact_json['interactions']).to_not include(
+        include("metadata" => nil)
+      )
     end
   end
 
@@ -79,6 +82,9 @@
       expect(pact_json['interactions']).to include(
         include("description" => "a request for alligators")
       )
+      expect(pact_json['interactions']).to_not include(
+        include("metadata" => nil)
+      )
     end
   end
 
@@ -120,6 +126,9 @@
       expect(pact_json['interactions']).to_not include(
         include("description" => "a request for zebras")
       )
+      expect(pact_json['interactions']).to_not include(
+        include("metadata" => nil)
+      )
     end
   end