Unit tests

Standard unit tests are created and executed same as for any other Java classes. There is nothing special. So if you for example have service:

package com.example.service.interfaces;

public interface CalculatorService {
    Integer add(Integer a, Integer b);

And its implementation:

package com.example.service.impl;

import com.example.service.interfaces.CalculatorService;
import org.springframework.stereotype.Service;

@Service(value = "multiplierService")
public class CalculatorServiceImpl implements CalculatorService {
    public Integer add(Integer a, Integer b) {
        return a + b;

If you are using for example JUnit just create test class:

import com.example.service.interfaces.CalculatorService;
import com.example.service.impl.CalculatorServiceImpl;

import static org.junit.Assert.assertEquals;
import org.junit.Test;

public class CalculatorServiceTest {
    public void testAddMethod() {
        CalculatorService calculator = new CalculatorServiceImpl();
        Integer sum = calculator.add(2, 2);
        assertEquals(4, sum);

Now if you are using Maven for your project just run command mvn test and see you result.