Spock - mocking external service

Question

I'm very new in spock framework testing and I didn't find any example where I can find needed information. Therefore, I think the best way is to show an example what I need to have.

1. e.g. test class in spock:

   def "getData" (){ // this is test of getData method from ExternalService
     when:
       Result result = externalService.getData()
     then:
       result.msg = 'SUCCESS'
   }
   

2. Service Class:

   public class ExternalService(){
     private ServiceConnector serviceConnector;
   
     public Result getData(){
       Result result = serviceConnector.callAndGet(); 
       prepareInformation(data);
       updateStatuses(data);
       return result;
     }
   }
   

3. Class Data as a Domain Class:

   public class Data {
     private String msg
     private int Id
     // +getters/setters
   }
   

And now I have getData test and would like to mock the only method callAndGet(). It means every time I call callAndGet I need to have object Data with msg SUCCESS but all other methods from getData method should be called normally.

Is it quite understandable? The question is how can we inject/mock the service class ExternalService into the spock test class?

Answer 1

What you need to do is to mock the ServiceConnector class and pass it via constructor (e.g.). See below:

@Grab('org.spockframework:spock-core:1.0-groovy-2.4')
@Grab('cglib:cglib-nodep:3.1')


import spock.lang.*

class Test extends Specification {
    def 'some spec'() {
        given:    
            def serviceConnector = Mock(ServiceConnector) {
                callAndGet() >> new Result(msg: 'SUCCESS')
            }
            def externalService = new ExternalService(serviceConnector)

        when:
            Result result = externalService.getData()

        then:
            result.msg == 'SUCCESS'
    }
}

public class ExternalService {
  private ServiceConnector serviceConnector

  public ExternalService(ServiceConnector serviceConnector) {
      this.serviceConnector = serviceConnector
  }

  public Result getData() {
    Result result = serviceConnector.callAndGet()

    prepareInformation(result)
    updateStatuses(result)
    result
  }

  private void prepareInformation(Result data) {
  }

  private void updateStatuses(Result data) {
  }
}

public class ServiceConnector {
    public Result callAndGet() {

    }    
}

public class Result {
    String msg
}