Styjun

I am testing a simple beginner spring boot application, but it keeps throwing NullPointerException for my service class and my repository class.

This is my controller class:

@EnableAutoConfiguration
@RestController
public class MyController 

 @Autowired
 private MyService service;


 @GetMapping("/welcome")
 public String home throws IOException 
 return service.getEntities();
 

This is the Service class:

@EnableAutoConfiguration
@Service
public class MyService{

@Autowired(required=true)
private MyRepository repository;

public MyService() 
;

public List<Entity> getEntities() throws IOException 
 return repository.findAll();
 

And this is the repository:

@Repository
public interface MyRepository extends JpaRepository<Entity, Long>

 List<Entity> findAll();

So, if I run the application everything is ok. The problem is when I run this test:

@RunWith(SpringRunner.class)
@ContextConfiguration(classes = MyService.class, MyController.class, Entity.class )
@ComponentScan("test.firstproject")
@EntityScan(basePackages = "test.firstproject.entities")
@SpringBootTest(webEnvironment = SpringBootTest.WebEnvironment.RANDOM_PORT)
@AutoConfigureTestDatabase(replace = Replace.NONE)
@EnableJpaRepositories("test.firstproject.repository")
@EnableAutoConfiguration
public class TestController 

 private MockMvc mvc = MockMvcBuilders.standaloneSetup(new MyController).build();

 public static final MediaType APPLICATION_JSON_UTF8 = new MediaType(MediaType.APPLICATION_JSON.getType(), MediaType.APPLICATION_JSON.getSubtype(), Charset.forName("utf8"));

 @Autowired
 private ObjectMapper objectMapper;


 @Test
 public void allEntities() 
 this.objectMapper = new ObjectMapper();
 try 
 ResultActions resultActions = this.mvc
 .perform(MockMvcRequestBuilders.get("/welcome").accept(MediaType.APPLICATION_JSON));
 this.mvc.perform(get("/welcome")).andExpect(status().isOk());
 MvcResult result = resultActions.andReturn();
 List<Object> list = objectMapper.readValue(result.getResponse().getContentAsString(), new TypeReference<List<Entity>>());
 for (Object c : list) 
 assertTrue(c.getClass().equals(Entity.class));
 

 catch (Exception e) 
 e.printStackTrace();
 

 

First, it threw NullPointerException when calling service.getEntities(). Then I've tried by initializing the service doing = new MyService(), but this time return repository.findAll(); throws the error. What's wrong?

EDIT - Stacktrace

org.springframework.web.util.NestedServletException: Request processing failed; nested exception is java.lang.NullPointerException
 at org.springframework.web.servlet.FrameworkServlet.processRequest(FrameworkServlet.java:1013)
 at org.springframework.web.servlet.FrameworkServlet.doGet(FrameworkServlet.java:897)
 at javax.servlet.http.HttpServlet.service(HttpServlet.java:634)
 at org.springframework.web.servlet.FrameworkServlet.service(FrameworkServlet.java:882)
 at org.springframework.test.web.servlet.TestDispatcherServlet.service(TestDispatcherServlet.java:71)
 at javax.servlet.http.HttpServlet.service(HttpServlet.java:741)
 at org.springframework.mock.web.MockFilterChain$ServletFilterProxy.doFilter(MockFilterChain.java:166)
 at org.springframework.mock.web.MockFilterChain.doFilter(MockFilterChain.java:133)
 at org.springframework.test.web.servlet.MockMvc.perform(MockMvc.java:182)
 at com.example.demo.TestController.getAllEntities(TestController.java:58)
 at java.base/jdk.internal.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
 at java.base/jdk.internal.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:62)
 at java.base/jdk.internal.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
 at java.base/java.lang.reflect.Method.invoke(Method.java:566)
 at org.junit.runners.model.FrameworkMethod$1.runReflectiveCall(FrameworkMethod.java:50)
 at org.junit.internal.runners.model.ReflectiveCallable.run(ReflectiveCallable.java:12)
 at org.junit.runners.model.FrameworkMethod.invokeExplosively(FrameworkMethod.java:47)
 at org.junit.internal.runners.statements.InvokeMethod.evaluate(InvokeMethod.java:17)
 at org.springframework.test.context.junit4.statements.RunBeforeTestExecutionCallbacks.evaluate(RunBeforeTestExecutionCallbacks.java:74)
 at org.springframework.test.context.junit4.statements.RunAfterTestExecutionCallbacks.evaluate(RunAfterTestExecutionCallbacks.java:84)
 at org.springframework.test.context.junit4.statements.RunBeforeTestMethodCallbacks.evaluate(RunBeforeTestMethodCallbacks.java:75)
 at org.springframework.test.context.junit4.statements.RunAfterTestMethodCallbacks.evaluate(RunAfterTestMethodCallbacks.java:86)
 at org.springframework.test.context.junit4.statements.SpringRepeat.evaluate(SpringRepeat.java:84)
 at org.junit.runners.ParentRunner.runLeaf(ParentRunner.java:325)
 at org.springframework.test.context.junit4.SpringJUnit4ClassRunner.runChild(SpringJUnit4ClassRunner.java:251)
 at org.springframework.test.context.junit4.SpringJUnit4ClassRunner.runChild(SpringJUnit4ClassRunner.java:97)
 at org.junit.runners.ParentRunner$3.run(ParentRunner.java:290)
 at org.junit.runners.ParentRunner$1.schedule(ParentRunner.java:71)
 at org.junit.runners.ParentRunner.runChildren(ParentRunner.java:288)
 at org.junit.runners.ParentRunner.access$000(ParentRunner.java:58)
 at org.junit.runners.ParentRunner$2.evaluate(ParentRunner.java:268)
 at org.springframework.test.context.junit4.statements.RunBeforeTestClassCallbacks.evaluate(RunBeforeTestClassCallbacks.java:61)
 at org.springframework.test.context.junit4.statements.RunAfterTestClassCallbacks.evaluate(RunAfterTestClassCallbacks.java:70)
 at org.junit.runners.ParentRunner.run(ParentRunner.java:363)
 at org.springframework.test.context.junit4.SpringJUnit4ClassRunner.run(SpringJUnit4ClassRunner.java:190)
 at org.eclipse.jdt.internal.junit4.runner.JUnit4TestReference.run(JUnit4TestReference.java:89)
 at org.eclipse.jdt.internal.junit.runner.TestExecution.run(TestExecution.java:41)
 at org.eclipse.jdt.internal.junit.runner.RemoteTestRunner.runTests(RemoteTestRunner.java:541)
 at org.eclipse.jdt.internal.junit.runner.RemoteTestRunner.runTests(RemoteTestRunner.java:763)
 at org.eclipse.jdt.internal.junit.runner.RemoteTestRunner.run(RemoteTestRunner.java:463)
 at org.eclipse.jdt.internal.junit.runner.RemoteTestRunner.main(RemoteTestRunner.java:209)
Caused by: java.lang.NullPointerException
 at com.springmiddleware.controllers.MyController.allEntities(MyController.java:32)
 at java.base/jdk.internal.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
 at java.base/jdk.internal.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:62)
 at java.base/jdk.internal.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
 at java.base/java.lang.reflect.Method.invoke(Method.java:566)
 at org.springframework.web.method.support.InvocableHandlerMethod.doInvoke(InvocableHandlerMethod.java:189)
 at org.springframework.web.method.support.InvocableHandlerMethod.invokeForRequest(InvocableHandlerMethod.java:138)
 at org.springframework.web.servlet.mvc.method.annotation.ServletInvocableHandlerMethod.invokeAndHandle(ServletInvocableHandlerMethod.java:102)
 at org.springframework.web.servlet.mvc.method.annotation.RequestMappingHandlerAdapter.invokeHandlerMethod(RequestMappingHandlerAdapter.java:895)
 at org.springframework.web.servlet.mvc.method.annotation.RequestMappingHandlerAdapter.handleInternal(RequestMappingHandlerAdapter.java:800)
 at org.springframework.web.servlet.mvc.method.AbstractHandlerMethodAdapter.handle(AbstractHandlerMethodAdapter.java:87)
 at org.springframework.web.servlet.DispatcherServlet.doDispatch(DispatcherServlet.java:1038)
 at org.springframework.web.servlet.DispatcherServlet.doService(DispatcherServlet.java:942)
 at org.springframework.web.servlet.FrameworkServlet.processRequest(FrameworkServlet.java:1005)
 ... 40 more

You created MyController using new in line:

private MockMvc mvc = MockMvcBuilders.standaloneSetup(new MyController()).build();

Spring probably not injected Service to it. Try autowire:

@Autowired
private MyController myController;

And move MockMvc instantiation to @Before method:

private MockMvc mvc;

@Before
public void initialize() 
 mvc = MockMvcBuilders.standaloneSetup(myController).build();