Extending ParentRunner in Junit

Question

I would like to run tests with extending from ParentRunner . I'm doing that for learning, not any specific scenario. I have the classes below and below there's the output as well. I don't understand a few things: 1. Why is "describeChild" called 3 times repeatedly? 2. why the tests didn't run?("doOne", and "doTwo")? Uncommentiing this line: //Result result = JUnitCore.runClasses(arg0.getClass()); is executing the tests but I don't understand why does it work that way? 3. and above all - what about that line: @SuiteClasses({ChildOne.class, ChildTwo.class})? it had no influence on the behaviour of the code... Many thanks to anybody who responds:-)

Suite class:

@RunWith(FamilyRunner.class)
@SuiteClasses({ChildOne.class, ChildTwo.class, ChildThree.class})
public class Suite {
//nothing here
}

Runner class:

public class FamilyRunner extends ParentRunner<ParentClass>{

public FamilyRunner(Class<?> klass) throws InitializationError {
        super(klass);
}


@Rule
public TestName name = new TestName();

@Override
protected List<ParentClass> getChildren() {

    List<ParentClass> list = new ArrayList<>();
    System.out.println("Adding items to list");
    list.add(new ChildOne());
    list.add(new ChildTwo());

    return list;
}


@Override
protected Description describeChild(ParentClass arg0) {
    System.out.println("describeChild class: " + arg0.getClass().getSimpleName());
    Description desc = Description.createTestDescription(name.getMethodName(), 
            name.getMethodName(), getClass().getAnnotations());

    return desc;
}

@Override
protected void runChild(ParentClass arg0, RunNotifier arg1) {
    System.out.println("runChild " + arg0.getClass().getSimpleName());
    //Result result = JUnitCore.runClasses(arg0.getClass());
}
}

and:

public class ParentClass {

    public ParentClass() {
         System.out.println("created parent class");
    }
}

public class ChildOne extends ParentClass {
    public ChildOne() {
        System.out.println("created ChildOne class");
    }

    @Test
    public void doOne(){
        System.out.println("doOne");
    }
}

public class ChildTwo extends ParentClass {
    public ChildTwo() {
        System.out.println("created ChildTwo class");
    }

    @Test
    public void doTwo(){
        System.out.println("doTwo");
    }
}

The console prints:

Adding items to list
created parent class
created ChildOne class
created parent class
created ChildTwo class
describeChild class: ChildOne
describeChild class: ChildTwo
describeChild class: ChildOne
describeChild class: ChildTwo
describeChild class: ChildOne
describeChild class: ChildTwo
runChild ChildOne
runChild ChildTwo

Answer 1

I can answer some questions.

About @SuiteClasses({ChildOne.class, ChildTwo.class}) you aren't building the list using this annotation values.

You can do this:

protected List<ParentClass> getChildren() {
    Annotation[] runnerAnnotations = super.getRunnerAnnotations();
    System.out.println(runnerAnnotations);

    Optional<Annotation> suitClass = Arrays.stream(runnerAnnotations)
            .filter(a -> a.annotationType().equals(SuiteClasses.class))
            .findFirst();

    List<ParentClass> list = new ArrayList<>();
    if (suitClass.isPresent()) {
        SuiteClasses s = (SuiteClasses) suitClass.get();
        s.value();
        System.out.println("Adding items to list");
        for (Class<?> c : s.value()) {
            Class<ParentClass> cp = (Class<ParentClass>) c;
            try {
                list.add(cp.newInstance());
            } catch (InstantiationException | IllegalAccessException e) {
                e.printStackTrace();
            }
        }
    }
    return list;
}

I think you can find more information in org.junit.runners.Suite source: http://grepcode.com/file/repo1.maven.org/maven2/junit/junit/4.8.1/org/junit/runners/Suite.java