当方法在 jUnit 中抛出异常时

Question

您如何处理在 jUnit 测试中引发异常的方法？如您所见，Question 类中的addAnswer 方法可能会引发异常。在shouldFailifTwoAnswerAreCorrect 方法中我想检查是否抛出异常，但在shouldAddAnswersToQuestion 中

我应该从私有 addAnswerToQuestion 方法中添加 throws MultipleAnswersAreCorrectException 并在 shouldAddAnswersToQuestion 中尝试/捕获，还是也应该在该方法中抛出它？

当方法在测试中抛出异常时你会怎么做？

public class QuestionTest {

    private Question question;

    @Before
    public void setUp() throws Exception {
        question = new Question("How many wheels are there on a car?", "car.png");
    }

    @Test
    public void shouldAddAnswersToQuestion() {

        addAnswerToQuestion(new Answer("It is 3", false));
        addAnswerToQuestion(new Answer("It is 4", true));
        addAnswerToQuestion(new Answer("It is 5", false));
        addAnswerToQuestion(new Answer("It is 6", false));

        assertEquals(4, question.getAnswers().size());
    }

    @Test(expected = MultipleAnswersAreCorrectException.class)
    public void shouldFailIfTwoAnswersAreCorrect() {

        addAnswerToQuestion(new Answer("It is 3", false));
        addAnswerToQuestion(new Answer("It is 4", true));
        addAnswerToQuestion(new Answer("It is 5", true));
        addAnswerToQuestion(new Answer("It is 6", false));
    }

    private void addAnswerToQuestion(Answer answer) {
        question.addAnswer(answer);
    }
}

问题类中的方法

public void addAnswer(Answer answer) throws MultipleAnswersAreCorrectException {

    boolean correctAnswerAdded = false;

    for (Answer element : answers) {
        if (element.getCorrect()) {
            correctAnswerAdded = true;
        }
    }

    if (correctAnswerAdded) {
        throw new MultipleAnswersAreCorrectException();
    } else {
        answers.add(answer);    
    }
}

Answer 1

您必须将throws 声明添加到addAnswerToQuestion，然后尝试/捕获异常或使用expected 属性或@Test：

@Test(expected=IOException.class)
public void test() {
    // test that should throw IOException to succeed.
}

Answer 2

在shouldAddAnswersToQuestion 测试中，如果您不期待MultipleAnswersAreCorrectException，那么您可以将块包围在 try/catch 中并编写断言失败条件，例如

    @Test
public void shouldAddAnswersToQuestion() {
  try{
       addAnswerToQuestion(new Answer("It is 3", false));
       addAnswerToQuestion(new Answer("It is 4", true));
       addAnswerToQuestion(new Answer("It is 5", false));
       addAnswerToQuestion(new Answer("It is 6", false));
       assertEquals(4, question.getAnswers().size());
   }catch(MultipleAnswersAreCorrectException  e){
     Assert.assertFail("Some self explainable failure statement");
   }
}

我认为让测试失败总是更好，而不是从测试中抛出异常，因为所有测试都应该因为断言失败而不是因为异常而失败。