Using junit test to pass command line argument to Spring Boot application

Question

I have a very basic Spring Boot application, which is expecting an argument from command line, and without it doesn\'t work. Here is the code.

@SpringBootApplica         


        

Answer 1

I would leave SpringBoot out of the equation.

You simply need to test the run method, without going through Spring Boot, since your goal is not to test spring boot, isn't it ? I suppose, the purpose of this test is more for regression, ensuring that your application always throws an IllegalArgumentException when no args are provided? Good old unit test still works to test a single method:

@RunWith(MockitoJUnitRunner.class)
public class ApplicationTest {

    @InjectMocks
    private Application app = new Application();

    @Mock
    private Reader reader;

    @Mock
    private Writer writer;

    @Test(expected = IllegalArgumentException.class)
    public void testNoArgs() throws Exception {
        app.run();
    }

    @Test
    public void testWithArgs() throws Exception {
        List list = new ArrayList();
        list.add("test");
        Mockito.when(reader.get(Mockito.anyString())).thenReturn(list);

        app.run("myarg");

        Mockito.verify(reader, VerificationModeFactory.times(1)).get(Mockito.anyString());
        Mockito.verify(writer, VerificationModeFactory.times(1)).write(list);
    }
}

I used Mockito to inject mocks for Reader and Writer:

    org.mockito
    mockito-all
    1.9.0
    test