JUnit 5: Specify execution order for nested tests

Question

Is it possible to execute several nested tests in between of some other tests with a fixed execution order?

E.g.

@TestInstance(Lifecycle.PER_CLASS)
@TestMethodOrder(OrderAnnotation.class)
class MyTest {

    private State state = State.ZERO;

    @Test
    @Order(1)
    public void step1() throws IOException {
        state = State.ONE;
    }

    @Order(2)  // sth like this, however this annotation isn't allowed here
    @Nested
    class WhileInStateOne {

        @Test
        public void step2a {
            Assumptions.assumeTrue(state == State.ONE);

            // test something
        }

        @Test
        public void step2b {
            Assumptions.assumeTrue(state == State.ONE);

            // test something else
        }

    }

    @Test
    @Order(3)
    public void step3() throws IOException {
        state = State.THREE;
    }

}

I know, that unit tests should in general be stateless, however in this case I can save a lot of execution time if I can reuse the state in a fixed order.

Grabble

You shouldn´t care about the execution time. Let them run on your pipeline automatically and skip it on LDEV - but you shouldn´t run them in order. That´s a hard break. – Argile

I suspected comments like this, that's why I wrote that I am aware of the fact that test should not have a state. But there are exceptions and I deliberately broke this "rule" as in my scenario this makes sense (it is more of an integration test anyway). I don't want a fundamental debate, I just want to know how to achieve what I have asked ;-) – Grabble

The documentation shows that nested tests does support ordering. So use it there, too. So your test nr 3 would be 5 and nested tests are Nr 3+4. – Argile

tried it, but tests in the nested class are still executed after the tests from outer classes – Grabble

Answer 1

Tests in nested classes are always executed after tests in the enclosing class. That cannot be changed.

Methods in the same class can be ordered as follows:

@TestMethodOrder(MethodOrderer.OrderAnnotation.class) 
public class TestCode { 
  
    @Test
    @Order(1) 
    public void primaryTest() 
    {  
    } 
      
    @Test
    @Order(2) 
    public void secondaryTest() 
    { 
    } 
} 

Nested inner test classes can be ordered as follows:

 @TestClassOrder(ClassOrderer.OrderAnnotation.class)
 class OrderedNestedTests {

     @Nested
     @Order(1)
     class PrimaryTests {
          // @Test methods ...
     }

     @Nested
     @Order(2)
     class SecondaryTests {
        // @Test methods ...
     }

}

Monetary

Thanks for the clear answer. Any chance this will change eventually? – Grabble

You're welcome. No, we (the JUnit Team) have no plans of mixing the execution order of tests between nested test classes and their enclosing classes, simply because that would violate the entire design principles of nested containers. – Monetary

So what happens when you have several @Nested tests? What is the order? How do you make the order predictive? AFAIK nested tests are there to organize your test suite. So for ex, you'd refactor a large test class (having the Order annotation on all tests) into several nested test classes but if you can't control the order of the nested tests then you can't do this refactoring since you're going to loose the order. Thx – Rinderpest

@VincentMassol you can control the order of the execution of nested classes since 5.8.0. Take a look at the release notes, 2nd point: junit.org/junit5/docs/5.8.0/release-notes/… Issue in GitHub: github.com/junit-team/junit5/issues/2699 – Carissacarita

Absolutely needed, today, the ability to order nested test classes but didn't care about the order in which their tests were executed. Glad to see it is supported! – Inhuman

Answer 2

You can now use @TestClassOrder(ClassOrderer.OrderAnnotation.class) on your main class.

Samy

This comment is identical to your answer but provides a lot more detail. – Severance