JUnit测试预期异常的正确方法

Question

大家好,我想知道这种测试我的异常的方式是否正常,我有这个例外我需要抛出第二个测试注释,我接收结果是一个红色的邪恶条,一个成功和一个失败,你可以猜到失败是我关心的,我有失败(); 但原因是因为我读到了测试异常的方法,现在我很困惑.

此外,我不得不说im willin得到绿色条,因为我期待异常,但我不知道失败是否是正确的方式来看到预期的异常的答案.

如果您有任何建议,我将不胜感激

@Before
    public void setUp() throws Exception {
        LogPack.logPacConfig(Constants.LOGGING_FILE);
        gtfri = "+RESP:GTFRI,380502,869606020101881,INCOFER-gv65,,10,1,1,0.0,0,888.1,-84.194560,9.955602,20170220074514,,,,,,0.0,,,,100,210100,,,,20170220074517,40A2$";
        weirdProtocol = "+RESP:GRI,380502,869606020101881,INCOFER-gv65,,10,1,1,0.0,0,888.1,-84.194560,9.955602,20170220074514,,,,,,0.0,,,,100,210100,,,,20170220074517,40A2$";
        factory = new LocomotiveFactory();
    }
    @Test
    public void GTFRICreationTester_shouldPass() throws TramaConProtolocoloDesconocido {
        assertTrue(factory.createLocomotive(gtfri, false, new Date()) instanceof LocomotiveGTFRI);
    }

    @Test(expected = TramaConProtolocoloDesconocido.class)
    public void GTFRICreationTester_shouldFail()  {
        try {
            factory.createLocomotive(weirdProtocol, false, new Date());
            fail("Expected an TramaConProtolocoloDesconocido");
        } catch (TramaConProtolocoloDesconocido e) {
            //assertSame("exception thrown as expected", "no se conoce el protocolo dado para la creacion de este factory", e.getMessage());;
        }
    }

Answer 1

测试预期异常有3种最常用的方法:

第一种方法是最常用的方法,但您只能使用它来测试预期异常的类型.如果ExceptionType不抛出此测试将失败:

@Test(expected = ExceptionType.class)
public void testSomething(){
    sut.doSomething();
}

此外,您无法使用此方法指定失败消息

更好的选择是使用ExpectedException JUnit @Rule.在这里,您可以为预期的异常断言更多

@Rule
public ExpectedException thrown = ExpectedException.none();

@Test
public void testSomething(){
    thrown.expect(ExceptionType.class);
    thrown.expectMessage("Error message");
    thrown.expectCause(is(new CauseOfExeption()));
    thrown.reportMissingExceptionWithMessage("Exception expected"); 
    //any other expectations
    sut.doSomething();
}

第三个选项将允许您执行与使用ExpectedException @Rule相同的操作,但所有断言都应手动编写.但是,此方法的优点是您可以使用任何自定义断言和所需的任何断言库:

@Test
public void testSomething(){
    try{
        sut.doSomething();
        fail("Expected exception");
    } catch(ExceptionType e) {
    //assert ExceptionType e
    } 
}