java - 在 junit 中使用@rule 检查错误代码

Question

我在 jUnit 中发现了 @Rule 注解可以更好地处理异常。 有没有办法检查错误代码？

目前我的代码看起来像(没有@Rule):

 @Test
    public void checkNullObject() {
    MyClass myClass= null;
    try {
        MyCustomClass.get(null); // it throws custom exception when null is passed
    } catch (CustomException e) { // error code is error.reason.null
        Assert.assertSame("error.reason.null", e.getInformationCode());
    }
    }

但是使用@Rule，我正在做以下事情:

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

        @Test
        public void checkNullObject() throws CustomException {
        exception.expect(CustomException .class);
        exception.expectMessage("Input object is null.");
        MyClass myClass= null;
        MyCustomClass.get(null);

        }

但是，我想做如下的事情:

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

        @Test
        public void checkNullObject() throws CustomException {
        exception.expect(CustomException .class);
       //currently below line is not legal. But I need to check errorcode.
        exception.errorCode("error.reason.null");
        MyClass myClass= null;
        MyCustomClass.get(null);

        }

Answer 1

您可以在带有 expect(Matcher<?> matcher) 的规则上使用自定义匹配器方法。

例如:

public class ErrorCodeMatcher extends BaseMatcher<CustomException> {
  private final String expectedCode;

  public ErrorCodeMatcher(String expectedCode) {
    this.expectedCode = expectedCode;
  }

  @Override
  public boolean matches(Object item) {
    CustomException e = (CustomException)item;
    return expectedCode.equals(e.getInformationCode());
  }
}

在测试中:

exception.expect(new ErrorCodeMatcher("error.reason.null"));