Merge pull request #85 from monzo/empty-noop-mock

Allow empty Noop() to be added to mock op chains

mock.go

@@ -135,6 +135,11 @@ func (mo mockMultiOp) Add(inOps ...Op) Op {
 			ops = append(ops, op...)
 		case mockOp:
 			ops = append(ops, op)
+		case multiOp:
+			if len(op) == 0 {
+				continue
+			}
+			panic("can't Add non-mock ops to mockMultiOp")
 		default:
 			panic("can't Add non-mock ops to mockMultiOp")
 		}

mock_test.go

@@ -514,6 +514,20 @@ func (s *MockSuite) TestNoop() {
 	s.Equal("Jill", users[1].Name)
 }
 
+// Don't panic when adding an empty Noop to an existing op chain
+func (s *MockSuite) TestEmptyNoop() {
+	addresses := s.insertAddresses()
+	addressToUpdate := addresses[0]
+	addressToUpdate.PostCode = "XYZ"
+	emptyNoop := Noop()
+	op := s.embMapTbl.Set(addressToUpdate)
+	op = op.Add(s.embTsTbl.Set(addressToUpdate))
+	s.NotPanics(func() {
+		op = op.Add(emptyNoop)
+	})
+	s.NoError(op.Run())
+}
+
 func (s *MockSuite) TestEmbedMapRead() {
 	expectedAddresses := s.insertAddresses()