I’m making some test but my mocking is not working.

This is my test class.

@UnitTest
@RunWith(MockitoJUnitRunner.class)
public class ResendMailingStrategyUnitTest {


    @Test
    public void sendTest() throws ResendException {

        Resend resendClient = Mockito.mock(Resend.class);
        Emails mockedEmails = Mockito.mock(Emails.class);

        ResendMailingStrategy resendMailingStrategy = new ResendMailingStrategy();
        ReflectionTestUtils.setField(resendMailingStrategy, "resendClient", resendClient);

        Mockito.when(resendClient.emails()).thenReturn(mockedEmails);
        Mockito.when(mockedEmails.send(Mockito.any(CreateEmailOptions.class))).thenReturn(null);

        resendMailingStrategy.send(StubProvider.getEmailMessageModelStub());

        Mockito.verify(resendClient).emails().send(Mockito.any(CreateEmailOptions.class));

    }

}

But my when(resendClient… is not working because method is not returning the mock, I’m getting this error then;

Cannot invoke “com.resend.services.emails.Emails.send(com.resend.services.emails.model.CreateEmailOptions)” because the return value of “com.resend.Resend.emails()” is null