From 34269b83fadbb509a2ce111666313ecab7955c62 Mon Sep 17 00:00:00 2001
From: Sam Rudge <samrudge@monzo.com>
Date: Fri, 30 Sep 2022 11:35:40 +0100
Subject: [PATCH] Allow empty Noop() to be added to mock op chains

---
 mock.go      |  5 +++++
 mock_test.go | 14 ++++++++++++++
 2 files changed, 19 insertions(+)

diff --git a/mock.go b/mock.go
index c3b4b2f..f6092eb 100644
--- a/mock.go
+++ b/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")
 		}
diff --git a/mock_test.go b/mock_test.go
index 682878b..594876e 100644
--- a/mock_test.go
+++ b/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()