JUnit Matcher的声明在哪里#startingWith？

Question

我浏览了JUnit的ExpectedExceptions"javadoc的,我不明白的地方startsWith在他们的例子来自(代码标记HERE).我检查了CoreMatcher实用程序类,但找不到任何静态startsWith方法.

该方法在哪里？

(我显然可以自己写,但这不是重点)

public static class HasExpectedException {
    @Rule
    public ExpectedException thrown = ExpectedException.none();

    @Test
    public void throwsNullPointerExceptionWithMessage() {
        thrown.expect(NullPointerException.class);
        thrown.expectMessage("happened?");
        thrown.expectMessage(startsWith("What")); //HERE
        throw new NullPointerException("What happened?");
    }
}

Answer 1

import static org.hamcrest.core.StringStartsWith.startsWith;

两者兼得

assertThat(msg, startsWith ("what"));

和

ExpectedException.none().expectMessage(startsWith("What")); //HERE

Answer 2

很可能这是Hamcrest Matchers类的startsWith方法.