您如何断言在 JUnit 4 测试中引发了某个异常? [英] How do you assert that a certain exception is thrown in JUnit 4 tests?

问题描述

如何以惯用方式使用 JUnit4 来测试某些代码是否引发异常?

How can I use JUnit4 idiomatically to test that some code throws an exception?

虽然我当然可以这样做:

While I can certainly do something like this:

@Test
public void testFooThrowsIndexOutOfBoundsException() {
  boolean thrown = false;

  try {
    foo.doStuff();
  } catch (IndexOutOfBoundsException e) {
    thrown = true;
  }

  assertTrue(thrown);
}

我记得有一个注解或一个 Assert.xyz 或 something 远不那么笨拙，而且在这类情况下更符合 JUnit 的精神.

I recall that there is an annotation or an Assert.xyz or something that is far less kludgy and far more in-the-spirit of JUnit for these sorts of situations.

推荐答案

这取决于 JUnit 版本和你使用的断言库.

It depends on the JUnit version and what assert libraries you use.

• 对于 JUnit5 和 4.13，请参阅答案 https://stackoverflow.com/a/2935935/2986984
• 如果您使用 assertJ 或 google-truth，请参阅答案 https://stackoverflow.com/a/41019785/2986984

JUnit <= 4.12 的原始答案是:

@Test(expected = IndexOutOfBoundsException.class)
public void testIndexOutOfBoundsException() {

    ArrayList emptyList = new ArrayList();
    Object o = emptyList.get(0);

}

虽然答案 https://stackoverflow.com/a/31826781/2986984 对 JUnit <= 有更多选择4.12.

Though answer https://stackoverflow.com/a/31826781/2986984 has more options for JUnit <= 4.12.

参考:

• JUnit 测试常见问题解答

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