Spock模拟-我的方法调用值没有被模拟

Question

When calling getMarkup() in my static method of my helper class it throws a NPE. What I did was mocking both the MarkupMaker and it's return value, a instance of Markup. Ultimately I want to call toString() of the Markup instance. Whatever I do - the call of getMarkup() is throwing a NPE. I cannot find any documentation telling me how to mock method calls value in spock in detail.

EDIT: I added the example. The call of maker.getMarkup() return null even tho I mocked it in the spock test.

Test.groovy

class TestExample extends Specification {

    @Shared
    MarkupMaker makerMock = Mock()
    @Shared
    MarkupObject markupMock = Mock()

    def setup() {
        markupMock.toString() >> "headline1"
        makerMock.getMarkup() >> markupMock
    }

    @Unroll
    def "Should return a Markupvalue #expectedvalue"(MarkupMaker helper, int tabElementIndex, String expectedValue) {
        expect:
        MarkupHelper.getMarkupForIndex(helper, tabElementIndex) == expectedValue
        where:
        helper    | tabElementIndex | expectedValue
        makerMock | 1               | "headline1"

    }

}

Helper.java (executed the method of the mocked object)

public class MarkupHelper {

  public static MarkupObject getMarkupForIndex(MarkupMaker maker, int index){
    if(index == 1){
      maker.getMarkup();
    }
    return null;
  }
}

MarkupMaker.java (one of the mocked objects)

public class MarkupMaker {

  public MarkupObject getMarkup() {
    return new MarkupObject();
  }
}

MarkupObject.java (the last mocked object which holds the value tested for)

public class MarkupObject {
  @Override
  public String toString() {
    return "headline1";
  }
}

Answer 1

删除@Shared上的@Shared ，因为@Shared不支持它。

Answer 2

In your example you have provided, MarkupHelper will always return null. You are simply calling the maker.getMarkup() and not doing anything with it. So the execution will continue and return null .

Leonard's answer is the correct one, since your use of @Shared why you are getting the NPE on the mocked object, but your test will still not be satisfied due to your MarkupHelper not actually doing what you'd expect.

Similarly, your MarkupObject mock that is stubbing the toString isn't going to work since by the time you want to use it, it'll be outside of the simulation and therefore won't be used. In order to handle that, you should have your MarkupHelper return a String like:

public static String getMarkupForIndex(MarkupMaker maker, int index){
    if(index == 1){
        return maker.getMarkup().toString();
    }
    return null;
}

If you still want your MarkupHelper to return a MarkupObject, in your test you'll instead need to create an expected MarkupObject that has the same properties as your actual one.

Answer 3

I would recommend to create and mock all objects inside every test method. In this case you will be sure every test is isolated and shared data will not affect on your result.

Concerned to your example I would cover the getMarkupForIndex method by these 2 tests:

@Unroll
def "getMarkupForIndex(..) returns null when the given index is #givenIndex"(){
    given:
    def mockedMaker = Mock(MarkupObject)

    when:
    def actualResult = MarkupHelper.getMarkupForIndex(mockedMaker, givenIndex)

    then:
    actualResult == null
    0 * _._ // no mock interaction at all

    where:
    givenIndex << [0, 2, 3]
}

def "getMarkupForIndex(..) returns a markup object when the given index is 1"(){
    given:
    def expectedMarkupObject = new MarkupObject()
    def mockedMaker = Mock(MarkupMaker) {
        getMarkup() >> expectedMarkupObject
    }

    when:
    def actualResult = MarkupHelper.getMarkupForIndex(mockedMaker, 1)

    then:
    actualResult.is(expectedMarkupObject)
    1 * mockedMaker.getMarkup()
}