JUnit for void delete method

问题

I am new to JUnit and trying to learn. How can we write a JUnit for a void method. I have a delete method which is void. I am writing the test like below but its not working. Please suggest.

Method for which I have to write test case.

public class DoseService {
  @Autowired
  private DoseRepository doseRepo;

  public void deleteDose(int id) {
    doseRepo.deleteById(id);
 }
}

My Test

@Autowired
private DoseService doseService;

@MockBean
public DoseRepository doseRepository;

@Test
public void testDeleteDose() {

    Dose dose = createDose();
    ArgumentCaptor<Dose> arg = ArgumentCaptor.forClass(Dose.class);
    doseService.deleteDose(dose.getDoseId());
    verify(doseRepository).deleteById(arg.capture().getDoseId());
    assertEquals("120", arg.getValue().getDoseValue());
}

private Dose createDose() {
    Dose dose = new Dose();
    dose.setDoseId(1);
    dose.setDoseValue("120");
    return dose;
}

Thanks in advance

Updated

java.lang.NullPointerException
at verify(doseRepository).deleteById(arg.capture().getDoseId());
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)

回答1:

A unit test should test ONLY the class it is written for. So no need to inject real object, only mocks. Also you don't need a Dose object, as the only thing you want is to test the DoseService object.

I would do the following:

@ExtendWith(MockitoExtension.class)//for JUnit 5, but you can add the JUnit 4 annotation
public class DoseServiceTest {
    @Mock
    private DoseRepository doseRepository;

    @InjectMocks
    private DoseService sut;//System Under Test

    @Test
    public void testDeleteDose() {
        int doseId=42;

        // perform the call
        sut.deleteDose(doseId);

        // verify the mocks
        verify(doseRepository, times(1)).deleteById(eq(doseId));
    }
}

回答2:

It's because you are verifying the delete method, but in your code, you are using the deleteById method.

This code should work:

verify(doseRepository).deleteById(arg.capture()); // changed to deleteById
assertEquals(dose, arg.capture());

回答3:

In the mocked action you need to capture the argument. And then you can assert anything you want based on the captured argument.

Maybe something like this?

verify(doseRepository).deleteById(arg.capture());
assertEquals(dose.getDoseId(), arg.getValue().getDoseId());

来源：https://stackoverflow.com/questions/53734415/junit-for-void-delete-method

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java

spring-boot

junit

mockito