fix(test): use copy in mockbroker SetHandlersByMap

Clone the given handlerMap (to prevent race conditions on modification),
and require further calls to SetHandlerByMap if the handlers need
updating mid test.

admin_test.go

@@ -1357,20 +1357,23 @@ func TestDeleteOffset(t *testing.T) {
 
 	// Test NoError
 	handlerMap["DeleteOffsetsRequest"] = NewMockDeleteOffsetRequest(t).SetDeletedOffset(ErrNoError, topic, partition, ErrNoError)
+	seedBroker.SetHandlerByMap(handlerMap)
 	err = admin.DeleteConsumerGroupOffset(group, topic, partition)
 	if err != nil {
 		t.Fatalf("DeleteConsumerGroupOffset failed with error %v", err)
 	}
 
 	// Test Error
 	handlerMap["DeleteOffsetsRequest"] = NewMockDeleteOffsetRequest(t).SetDeletedOffset(ErrNotCoordinatorForConsumer, topic, partition, ErrNoError)
+	seedBroker.SetHandlerByMap(handlerMap)
 	err = admin.DeleteConsumerGroupOffset(group, topic, partition)
 	if err != ErrNotCoordinatorForConsumer {
 		t.Fatalf("DeleteConsumerGroupOffset should have failed with error %v", ErrNotCoordinatorForConsumer)
 	}
 
 	// Test Error for partition
 	handlerMap["DeleteOffsetsRequest"] = NewMockDeleteOffsetRequest(t).SetDeletedOffset(ErrNoError, topic, partition, ErrGroupSubscribedToTopic)
+	seedBroker.SetHandlerByMap(handlerMap)
 	err = admin.DeleteConsumerGroupOffset(group, topic, partition)
 	if err != ErrGroupSubscribedToTopic {
 		t.Fatalf("DeleteConsumerGroupOffset should have failed with error %v", ErrGroupSubscribedToTopic)

mockbroker.go

@@ -83,9 +83,13 @@ func (b *MockBroker) SetLatency(latency time.Duration) {
 // and uses the found MockResponse instance to generate an appropriate reply.
 // If the request type is not found in the map then nothing is sent.
 func (b *MockBroker) SetHandlerByMap(handlerMap map[string]MockResponse) {
+	fnMap := make(map[string]MockResponse)
+	for k, v := range handlerMap {
+		fnMap[k] = v
+	}
 	b.setHandler(func(req *request) (res encoderWithHeader) {
 		reqTypeName := reflect.TypeOf(req.body).Elem().Name()
-		mockResponse := handlerMap[reqTypeName]
+		mockResponse := fnMap[reqTypeName]
 		if mockResponse == nil {
 			return nil
 		}