Migrating from JUnit 4 to JUnit 5 issue (#RunWith to #ExtendWith) - unit-testing

Question

I am trying to convert the test-code of a Spring Boot controller from JUnit 4 to JUnit 5. I almost replaced all the annotations of JUnit 4 with JUnit 5 but got some issue when tried to replace #RunWith with #ExtendWith.
#ExtendWith(SpringExtension.class)
#WebMvcTest(value = HappyPostController.class, secure = false)
#TestInstance(TestInstance.Lifecycle.PER_CLASS)
public class HappyPostControllerTest {
#Autowired
private MockMvc mockMvc;
#Mock
private HappyPostServiceImpl happyPostService;
#InjectMocks
private HappyPostController happyPostController;
#BeforeAll
public void initialize() {
happyPostController = new HappyPostController(happyPostService);
MockitoAnnotations.initMocks(this);
this.mockMvc = MockMvcBuilders
.standaloneSetup(happyPostController)
.build();
}
#Test
public void testMockCreation() {
Assertions.assertNotNull(happyPostService);
Assertions.assertNotNull(mockMvc);
}
//..... other test methods
}
The errors:
java.lang.IllegalStateException: Failed to load ApplicationContext
......
Caused by: org.springframework.beans.factory.UnsatisfiedDependencyException: Error creating bean with name 'happyPostController' defined in file [....\HappyPostController.class]: Unsatisfied dependency expressed through constructor parameter 0; nested exception is org.springframework.beans.factory.NoSuchBeanDefinitionException: No qualifying bean of type 'com.rok.capp.service.HappyPostService' available: expected at least 1 bean which qualifies as autowire candidate. Dependency annotations: {}
.....
Caused by: org.springframework.beans.factory.NoSuchBeanDefinitionException: No qualifying bean of type 'com.rok.capp.service.HappyPostService' available: expected at least 1 bean which qualifies as autowire candidate. Dependency annotations: {}
........
Test ignored.
I tried to find the solution but failed. Please help.
Thanks

Answer 1

I don't know what your JUnit 4 based version of that test class looked like, but the example you have provided is an unnecessary mixture of an integration test and a unit test.
You're using the SpringExtension to create an ApplicationContext, but then you never use the ApplicationContext or any other features from the Spring TestContext Framework or Spring Boot Test.
So, the best solution is simply to get rid of all of the unnecessary integration testing support and rewrite your test class as follows.
#TestInstance(TestInstance.Lifecycle.PER_CLASS)
class HappyPostControllerTest {
#Mock
HappyPostServiceImpl happyPostService;
MockMvc mockMvc;
#BeforeAll
void initialize() {
MockitoAnnotations.initMocks(this);
HappyPostController happyPostController = new HappyPostController(happyPostService);
this.mockMvc = MockMvcBuilders
.standaloneSetup(happyPostController)
.build();
}
#Test
void testMockCreation() {
assertNotNull(happyPostService);
assertNotNull(mockMvc);
}
//..... other test methods
}
Regards,
Sam (author of the Spring TestContext Framework)

Answer 2

I found a solution here : http://www.bytestree.com/spring/spring-boot-2-junit-5-rest-api-unit-testing/
Here it is updated to your case :
import org.junit.jupiter.api.Test;
import org.junit.jupiter.api.extension.ExtendWith;
import org.mockito.Mockito;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.boot.test.autoconfigure.web.servlet.WebMvcTest;
import org.springframework.boot.test.mock.mockito.MockBean;
import org.springframework.test.context.junit.jupiter.SpringExtension;
import org.springframework.test.web.servlet.MockMvc;
import org.springframework.test.web.servlet.request.MockMvcRequestBuilders;
import org.springframework.test.web.servlet.result.MockMvcResultMatchers;
#ExtendWith(SpringExtension.class)
#WebMvcTest(HappyPostController.class)
class LotteryControllerTest {
#Autowired
private MockMvc mockMvc;
#MockBean
private HappyPostServiceImpl happyPostService;
#Test
public void should_get() throws Exception {
// Given
Mockito.when(happyPostService.whatevermethod()).thenReturn(someresult);
// When
this.mockMvc.perform(MockMvcRequestBuilders.get("/your_api"))
// Then
.andExpect(MockMvcResultMatchers.status().isOk());
}
using those dependencies
<dependency>
<groupId>org.junit.jupiter</groupId>
<artifactId>junit-jupiter-engine</artifactId>
<version>5.2.0</version>
</dependency>
<dependency>
<groupId>org.mockito</groupId>
<artifactId>mockito-core</artifactId>
<version>2.21.0</version>
</dependency>
<dependency>
<groupId>org.mockito</groupId>
<artifactId>mockito-junit-jupiter</artifactId>
<version>2.21.0</version>
</dependency>