春季MockMvc测试：mvc.perform（）的NullPointerException

Question

I am new to unit test in spring Boot. I am trying to run a simple test of the controller. But i'am getting a NullPointerException.

here is my code :

The controller class:

@RequestMapping("/trainings")
public class TrainingController {

@Autowired
TrainingService ts;

@PostMapping()
public JsonResponse<AllTrainings> getTrainings(){
    JsonResponse<AllTrainings> json = new JsonResponse<AllTrainings>();
    json.setStatus(JsonResponse.Status.OK);
    json.setData(new AllTrainings(ts.getTrainings()));
    return json;
}}

The TrainingTest :

@RunWith(SpringRunner.class)
public abstract class TrainingTest {

protected MockMvc mvc;
protected ObjectMapper mapper = new ObjectMapper();

@Before
public void setup() {
    MockitoAnnotations.initMocks(this);
}

@Test
public abstract void testGetTrainings() throws Exception;

@Test
public abstract void testGetTrainingById() throws Exception;

protected String toJson(Object object) throws JsonProcessingException {
    return mapper.writeValueAsString(object);
}
}

The TrainingControllerTest :

public class TrainingControllerTest extends TrainingTest{
@InjectMocks protected TrainingController controller;

@MockBean
TrainingRepository trainingRepo;

@Before
public void setup(){
    super.setup();
    mvc = MockMvcBuilders.standaloneSetup(this.controller).build();
}

@Override
public void testGetTrainings() throws Exception {
    Training ang = new Training("TR0004");

    Mockito
        .when(this.trainingRepo.findAll())
        .thenReturn(Arrays.asList(ang));

    mvc.perform(MockMvcRequestBuilders.get("/trainings")
            .contentType(MediaType.APPLICATION_JSON_VALUE))
        .andDo(MockMvcResultHandlers.print())
        .andExpect(MockMvcResultMatchers.status().isOk());      
}

And here the error i'am getting:

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.doPost(FrameworkServlet.java:908)
at javax.servlet.http.HttpServlet.service(HttpServlet.java:660)
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 fr.ter.forco.training.TrainingControllerTest.testGetTrainings(TrainingControllerTest.java:41)
at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
at sun.reflect.NativeMethodAccessorImpl.invoke(Unknown Source)
at sun.reflect.DelegatingMethodAccessorImpl.invoke(Unknown Source)
at java.lang.reflect.Method.invoke(Unknown Source)
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.junit.internal.runners.statements.RunBefores.evaluate(RunBefores.java:26)
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 fr.ter.forco.controllers.TrainingController.getTrainings(TrainingController.java:38)
at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
at sun.reflect.NativeMethodAccessorImpl.invoke(Unknown Source)
at sun.reflect.DelegatingMethodAccessorImpl.invoke(Unknown Source)
at java.lang.reflect.Method.invoke(Unknown Source)
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)
... 41 more

The exception appears in the mvc.perform! I really don't know why i'am getting this error.

Thank you.

Answer 1

I'm not sure why you're getting this error but maybe if you add the @AutoConfigureMockMvc above your test class it could work? I always add this annotation when making use of MockMvc.