用于比较超类和子类的Hamcrest匹配器

Question

我有以下课程：

abstract class Answer<T> {}
class AnswerInt extends Answer<Integer> {}
class AnswerText extends Answer<String> {}

现在我想在下面的测试中使用Hamcrest Matcher（它只是一个简化的示例）：

@Test
public void test() {
    Answer a = new AnswerInt(5);
    assertThat(a, is(new AnswerInt(5))); // Compile error
}    

Map<String,Answer> answerMap = questionary.getAnswerMap();
assertThat(answerMap, allOf(
    hasEntry("var1", new AnswerInt(5)),
    hasEntry("var2", new AnswerText("foo"))
));

但我也犯了同样的错误。

我使用的是Hamcrest 1.3版

Answer 1

如果您使用Java8运行测试，它将编译。对于以前的版本，您必须给编译器一个提示：

@Test
public void test() {
    Answer a = new AnswerInt(5);
    assertThat(a, Matchers.<Answer>is(new AnswerInt(5)));
}