Spring cloud Stream Solace Unit Test

Hi, I am using TestChannelBinderConfiguration. I have resolved the dependency issues by adding other classes in the argument,
new SpringApplicationBuilder(
TestChannelBinderConfiguration.getCompleteConfiguration(
MessageReceiver.class, xxx.class, yyy.class ))
in my yyy.class, i have mongotemplate and mongoclient used. How to mock them, Please suggest if any inputs.
“Catching”,“thrown”:{“commonElementCount”:0,“localizedMessage”:“Timed out after 30000 ms while waiting to connect. Client view of cluster state is {type=UNKNOWN, servers=[{address=localhost:27017, type=UNKNOWN, state=CONNECTING, exception={com.mongodb.MongoSocketOpenException: Exception opening socket}, caused by {java.net.ConnectException: Connection refused: connect}}]”,“message”:"Timed out after 30000 ms while waiting to connect.

How to mock this ?
@Autowired
 public SafeStoreDaoImpl(MongoClient mongoClient) {
  this.mongoClient = mongoClient;
 }