Run JUnit tests in Method Order With Custom Annotation

by MemoryNotFound · Published December 16, 2014 · Updated October 19, 2017

By default JUnit does not support to run JUnit tests in method order. JUnit only provides to run ordered method execution by name ascending NAME_ASCENDING or descending JVM.

It is a bad practice to depend on the order of execution of your unit tests. But sometimes you have hit a brick wall and you need the specific order of execution.

Creating JUnit tests in Method Order

We can use the @RunWith annotation to map our custom OrderedRunner class that will sort the method executions via our custom @Order annotation.

package com.memorynotfound.test;

import org.junit.Test;
import org.junit.runner.RunWith;

@RunWith(OrderedRunner.class)
public class OrderedJUnitTest {

    @Test
    @Order(order = 2)
    public void second(){
        System.out.println("second");
    }

    @Test
    @Order(order = 3)
    public void third(){
        System.out.println("third");
    }

    @Test
    @Order(order = 1)
    public void first(){
        System.out.println("first");
    }
}

Creating custom order annotation

The @Order annotation takes an int that will be used to determine the order.

package com.memorynotfound.test;

import java.lang.annotation.ElementType;
import java.lang.annotation.Retention;
import java.lang.annotation.RetentionPolicy;
import java.lang.annotation.Target;

@Retention(RetentionPolicy.RUNTIME)
@Target({ ElementType.METHOD})
public @interface Order {
    public int order();
}

Creating custom orderedRunner

This class does the actual ordering of our JUnit methods.

package com.memorynotfound.test;

import org.junit.runners.BlockJUnit4ClassRunner;
import org.junit.runners.model.FrameworkMethod;
import org.junit.runners.model.InitializationError;

import java.util.ArrayList;
import java.util.Collections;
import java.util.Comparator;
import java.util.List;

public class OrderedRunner extends BlockJUnit4ClassRunner {

    public OrderedRunner(Class<?> clazz) throws InitializationError {
        super(clazz);
    }

    @Override
    protected List<FrameworkMethod> computeTestMethods() {
        List<FrameworkMethod> list = super.computeTestMethods();
        List<FrameworkMethod> copy = new ArrayList<FrameworkMethod>(list);
        Collections.sort(copy, new Comparator<FrameworkMethod>() {
            @Override
            public int compare(FrameworkMethod f1, FrameworkMethod f2) {
                Order o1 = f1.getAnnotation(Order.class);
                Order o2 = f2.getAnnotation(Order.class);

                if (o1 == null || o2 == null)
                    return -1;

                return o1.order() - o2.order();
            }
        });
        return copy;
    }
}