spock framework override method in test class

Question

Tested class:

public class ClassForTest {

    public String hello(){
        return "hello " + getClassName();
    }

    public String getClassName(){
        return ClassForTest.class.getName();
    }    

}

Spock class:

    class ClassForSpockTest extends Specification{
    def setupSpec(){ 
       ClassForTest.metaClass.getClassName={"ClassForSpockTest"} 

    }

    def "override test"(){
        setup:
        ClassForTest cft = new ClassForTest()   

        expect:
        cft.getClassName()  == "ClassForSpockTest"
    }

    def "mock test"(){
        setup:
        ClassForTest cft = new ClassForTest()   

        expect:
        cft.hello() == "hello ClassForSpockTest"
    }


}

override test test is passed! Mock test is crashing, cft.hello() return "hello ClassForTest"

Answer 1

You can't use the metaclass to override a method call in a Java class from another method in that class. This is a limitation of spock, Java, and groovy. In this case, you have to use other mocking techniques. For example, you can use subclassing:

 setup:
 ClassForTest cft = new ClassForTest() {
     String getClassName() {"ClassForSpockTest"} 
 }