[FIXED] Email Mocking is failing

Issue

Im trying to mock the send email functionality which sends out email when a particular job/task is completed. When i try to unit test it getting below error. Is this the right way to test it or something wrong or missing anything.

@Mock
private MailServiceImpl mailService;

@Mock
private JavaMailSenderImpl javaMailSender;


@Before
public  void setUp() {
    MockitoAnnotations.initMocks(this);
    mailService=new MailServiceImpl(javaMailSender);

}


@Test
public void testSendEmail() {

    try {
        doNothing().when(mailService).sendMail(getEmailProperties());
        mailService.sendMail(getEmailProperties()); 
        verify(mailService,times(1)).sendMail(getEmailProperties());
    } catch (Exception e) {
        Assert.fail(e.getMessage());
    }

}

public EmailProperties getEmailProperties() {

    EmailProperties emailProperties = new EmailProperties();

    emailProperties.setFromAddress("[email protected]");
    emailProperties.setToAddress("[email protected]");
    emailProperties.setEmailBody("Test");
    emailProperties.setSubject("Test email");
    emailProperties.setAttachment((File) null);
    emailProperties.setMessageType(1);

    return emailProperties;
  }

Below is the error message is thrown from testSendEmail method. Any suggestions or any other ways to test it. google search didn't help much.

java.lang.AssertionError: 
    Argument passed to when() is not a mock!
    Example of correct stubbing:
    doThrow(new RuntimeException()).when(mock).someMethod();
    at org.junit.Assert.fail(Assert.java:88)
    at com.xx.xx.xx.mail.MailServiceTest.testSendEmail(MailServiceTest.java:52)
    at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
    at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:62)
    at 
sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
    at java.lang.reflect.Method.invoke(Method.java:498)
    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.junit.internal.runners.statements.RunBefores.evaluate(RunBefores.java:26)
    at org.junit.runners.ParentRunner.runLeaf(ParentRunner.java:325)
    at org.junit.runners.BlockJUnit4ClassRunner.runChild(BlockJUnit4ClassRunner.java:78)
    at org.junit.runners.BlockJUnit4ClassRunner.runChild(BlockJUnit4ClassRunner.java:57)
    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.junit.runners.ParentRunner.run(ParentRunner.java:363)
    at org.eclipse.jdt.internal.junit4.runner.JUnit4TestReference.run(JUnit4TestReference.java:86)
    at org.eclipse.jdt.internal.junit.runner.TestExecution.run(TestExecution.java:38)
    at org.eclipse.jdt.internal.junit.runner.RemoteTestRunner.runTests(RemoteTestRunner.java:538)
    at org.eclipse.jdt.internal.junit.runner.RemoteTestRunner.runTests(RemoteTestRunner.java:760)
    at org.eclipse.jdt.internal.junit.runner.RemoteTestRunner.run(RemoteTestRunner.java:460)
    at org.eclipse.jdt.internal.junit.runner.RemoteTestRunner.main(RemoteTestRunner.java:206)

Solution

removal of doNothing().when(mailService).sendMail(getEmailProperties()); fixed the issue. Not sure what was causing this issue

Answered By - NKR