Test cases in inner classes with JUnit

Question

I read about Structuring Unit Tests with having a test class per class and an inner class per method. Figured that seemed like a handy way to organize the tests, so I tried it in our Java project. However, the tests in the inner classes doesn't seem to be picked up at all.

I did it roughly like this:

public class DogTests
{
    public class BarkTests
    {
        @Test
        public void quietBark_IsAtLeastAudible() { }

        @Test
        public void loudBark_ScaresAveragePerson() { }
    }

    public class EatTests
    {
        @Test
        public void normalFood_IsEaten() { }

        @Test
        public void badFood_ThrowsFit() { }
    }
}

Does JUnit not support this, or am I just doing it wrong?

Answer 1

public class ServicesTest extends TestBase {

   public static class TestLogon{

       @Test
       public void testLogonRequest() throws Exception {
         //My Test Code
       }
   }
}

Making the inner class static works for me.

Answer 2

In JUnit 5, you simply mark non-static inner classes as @Nested:

import org.junit.jupiter.api.Nested;
import org.junit.jupiter.api.Test;

public class DogTests {
    @Nested
    public class BarkTests {
        @Test
        public void quietBark_IsAtLeastAudible() { }

        @Test
        public void loudBark_ScaresAveragePerson() { }
    }

    @Nested
    public class EatTests {
        @Test
        public void normalFood_IsEaten() { }

        @Test
        public void badFood_ThrowsFit() { }
    }
}

Answer 3

I think some of the answers might be for older versions of JUnit. In JUnit 4 this worked for me :

@RunWith(DogTests.class)
@SuiteClasses({ DogTests.BarkTests.class, DogTests.EatTests.class })
public class DogTests extends Suite
{
    public DogTests(Class<?> klass, RunnerBuilder builder) throws InitializationError {
        super(klass, builder);
    }

    public static class BarkTests
    {
        @Test
        public void quietBark_IsAtLeastAudible() { }

        @Test
        public void loudBark_ScaresAveragePerson() { }
    }

    public static class EatTests
    {
        @Test
        public void normalFood_IsEaten() { }

        @Test
        public void badFood_ThrowsFit() { }
    }
}

Answer 4

You should annontate your class with @RunWith(Enclosed.class), and like others said, declare the inner classes as static:

@RunWith(Enclosed.class)
public class DogTests
  {
  public static class BarkTests
  {
    @Test
    public void quietBark_IsAtLeastAudible() { }

    @Test
    public void loudBark_ScaresAveragePerson() { }
  }

  public static class EatTests
  {
    @Test
    public void normalFood_IsEaten() { }

    @Test
    public void badFood_ThrowsFit() { }
  }
}

Answer 5

I've had success with Nitor Creation's Nested Runner as well.

How to use Nitor Creation's Nested Runner

There is a post explaining it here:

Add this dependency:

<dependency>
    <groupId>com.nitorcreations</groupId>
    <artifactId>junit-runners</artifactId>
    <version>1.2</version>
    <scope>test</scope>
</dependency>

And a @RunWith to your test:

import com.nitorcreations.junit.runners.NestedRunner
import org.junit.Before;
import org.junit.Test;
import org.junit.runner.RunWith;
import static org.junit.Assert.*;

@RunWith(NestedRunner.class)
public class RepositoryUserServiceTest {

    public class RegisterNewUserAccount {

        public class WhenUserUsesSocialSignIn {

            public class WhenUserAccountIsFoundWithEmailAddress {

                @Test
                public void shouldThrowException() {
                     assertTrue(true);
                }
            }

        }
    }
}

PS: The example code has been taken and modified from the above blog post