What is the cause of java.lang.NullPointerException in my spring boot mockMVC test case?

Question

MyCode

 @AutoConfigureMockMvc
    public class NewsletterTest {

      @Autowired
      private MockMvc mockMvc;


      @MockBean
      private NewsletterService service;

      @Test
      public void deleteNewsletterShouldDelete() throws Exception {

        this.mockMvc.perform(MockMvcRequestBuilders
                .delete("/delete-newsletter/11")
                .contentType(MediaType.APPLICATION_JSON))
            .andExpect(status().isOk());

        verify(service, times(1)).deleteNewsletter(11L);

    }

The error:

java.lang.NullPointerException
    at controller.NewsletterTest.deleteNewsletterShouldDelete(NewsletterTest.java:33)
    at java.base/jdk.internal.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
    at java.base/jdk.internal.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:62)
    at

In my spring boot test case, I am using @AutoConfigureMockMvc and @MockBean to test a delete method in my newsletter controller. However, I am encountering a java.lang.NullPointerException at line 33 of my test case. I want to understand the cause of this error.

Hello! This is quite hard to know what your issue might be as we don't have the line number. But I guess the line with `this.mockMvc.perform` throws the NPE? — A Le Dref, Feb 03 '23 at 10:00
Yes, Line 33 is this.mockMvc.perform, it throws the NPE because mockMvc is null but i don't know why? — Mark likes Quark, Feb 03 '23 at 10:04

score 1 · Accepted Answer · answered Feb 03 '23 at 10:03

1

I see that your only anontation on your test is @AutoConfigureMockMvc. However that is not sufficient to start a Spring Boot application context.

As you are targeting a controller you should at least add @WebMvcTest(controllers=[controller_class_here].

This will setup everything and maybe resolve your NullPointerException.

Also doing so you won't need the @AutoconfigureMockMvc annotation

answered Feb 03 '23 at 10:03

A Le Dref

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3
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@Mark likes Quark do not hesitate to mark as accepted answers if it unblocked you! :) – A Le Dref Feb 03 '23 at 10:14
Yeah i tried it like this: @WebMvcTest(controllers=NewsletterController.class) But it still gives me the exact same NPE – Mark likes Quark Feb 03 '23 at 10:26
Do you use the correct import for the `@Test` annotation? Importing `junit.test` instead of `junit;jupiter.api.Test` can also cause this kind of issue – A Le Dref Feb 03 '23 at 10:42
The Test just gets ignored now and the junit.test import is not working for me – Mark likes Quark Feb 03 '23 at 11:47

What is the cause of java.lang.NullPointerException in my spring boot mockMVC test case?

1 Answers1