How to test Service using PowerMock with DAO in Spring Boot ?

Pre Requisite:

Make sure you have the below powermock maven dependencies.

Add the below dependencies to your pom.xml file:

<properties>
 <powermock-version>2.0.4</powermock-version>
</properties>

<dependency>
 <groupId>org.powermock</groupId>
 <artifactId>powermock-api-mockito2</artifactId>
 <version>${powermock-version}</version>
 <scope>test</scope>
</dependency>
<dependency>
 <groupId>org.powermock</groupId>
 <artifactId>powermock-module-junit4</artifactId>
 <version>${powermock-version}</version>
 <scope>test</scope>
</dependency>
<dependency>
 <groupId>org.powermock</groupId>
 <artifactId>powermock-api-easymock</artifactId>
 <version>${powermock-version}</version>
 <scope>test</scope>
</dependency>
<dependency>
 <groupId>org.powermock</groupId>
 <artifactId>powermock-module-junit4-rule</artifactId>
 <version>${powermock-version}</version>
 <scope>test</scope>
</dependency>

Step 1: Add @RunWith at class level

@RunWith(PowerMockRunner.class)

your class with @RunWith annotation looks similar to this:

import org.junit.runner.RunWith;
import org.powermock.modules.junit4.PowerMockRunner;
import static org.junit.Assert.assertEquals;

@RunWith(PowerMockRunner.class)
public class CouponServiceImplTest {

}

Step 2: Add @InjectMocks annotation to your actual service class

People who are familiar with Mockito, we use @Autowired directly to call the methods from our junits. Same way, if you are using Mockito then we need use @InjectMocks for our actual service class where we are trying to write the test cases for the classpath.

@RunWith(PowerMockRunner.class)
public class CouponServiceImplTest {

 @InjectMocks
 CouponServiceImpl couponServiceImpl;

}

Step 3: Add @Mock annotation to all your dependent classes like DAO’s and other service classes.

@RunWith(PowerMockRunner.class)
public class CouponServiceImplTest {

 @InjectMocks
 CouponServiceImpl couponServiceImpl;

 @Mock
 CouponDao couponDao;
}

Add @Mock annotation for all your dependent classes like other service implementation and DAO’s.

Step 4: Write the Test cases

@RunWith(PowerMockRunner.class)
public class CouponServiceImplTest {

 @InjectMocks
 CouponServiceImpl couponServiceImpl;

 @Mock
 CouponDao couponDao;

 @Before
 public void init() throws Exception {
   MockitoAnnotations.initMocks(this);
   List<Coupon> coupons = new ArrayList<>();
   Coupon coupon = new Coupon();
   coupon.setCouponId(1);
   coupon.setCouponTitle("10% OFF on Electronics");
   coupon.setCouponCode("SAVEJI10");
   coupons.add(coupon);
   when(couponDao.findAll()).thenReturn(coupons);
}

 @Test
 public void testCoupons(){
   Store store = new Store();
   store.setStoreId(3);
   Map<Store, List<Coupons>> result = couponServiceImpl.getCoupons(store);
   assertEquals(result.size(), 1);
}
}

That’s it. Now you can run testCoupons method to test the getCoupons method of couponServiceImpl. Same way you can write n number of methods as per your need for all your possible test cases for both positive and negative.

Bonus

@Before can be effectively used with PowerMock.

When you want to test several methods and all needs some datasets in common then instead of repeating everything in all the test case methods, you can just do kind of prepopulation/preinitialize in @Before method only.

So that you do not want to repeat the same steps again and again.