[FAB-4006] SDK Go - Update mock broadcast server

Add the ability to Broadcast mock server to send
successful response or error response

Change-Id: Idedaf8a99fc8f585a04b046390ba854e9eed79f1
Signed-off-by: Firas Qutishat <firas.qutishat@securekey.com>

Author: Firas Qutishat

fabric-client/mocks/mockbroadcastserver.go

@@ -35,14 +35,22 @@ var TestBlock = &orderer.DeliverResponse{
 	},
 }
 
+var broadcastResponseSuccess = &orderer.BroadcastResponse{Status: common.Status_SUCCESS}
+var broadcastResponseError = &orderer.BroadcastResponse{Status: common.Status_INTERNAL_SERVER_ERROR}
+
 // MockBroadcastServer mock broadcast server
 type MockBroadcastServer struct {
-	DeliverError error
+	DeliverError                 error
+	BroadcastInternalServerError bool
 }
 
 // Broadcast mock broadcast
-func (m *MockBroadcastServer) Broadcast(orderer.AtomicBroadcast_BroadcastServer) error {
-	// Not implemented
+func (m *MockBroadcastServer) Broadcast(server orderer.AtomicBroadcast_BroadcastServer) error {
+	if m.BroadcastInternalServerError {
+		server.Send(broadcastResponseError)
+		return nil
+	}
+	server.Send(broadcastResponseSuccess)
 	return nil
 }