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使用hasItem Hamcrest Matcher时“找不到合适的方法”

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当我运行以下jUnit测试时:

@Test
public void test(){
    List<Map<String,String>> data=new ArrayList<>();
    Map<String,String> map=new HashMap<>();
    map.put("x","y");
    data.add(map);

    assertThat(data, hasItem(hasKey("x")));
}

我明白了:

Error:(239, 9) java: no suitable method found for assertThat(java.util.List>,org.hamcrest.Matcher>>)
    method org.junit.Assert.assertThat(java.lang.String,T,org.hamcrest.Matcher) is not applicable
      (cannot infer type-variable(s) T
        (actual and formal argument lists differ in length))
    method org.junit.Assert.assertThat(T,org.hamcrest.Matcher) is not applicable
      (inferred type does not conform to upper bound(s)
        inferred: java.util.List>
        upper bound(s): java.lang.Iterable>,java.lang.Object)

看起来仿制药中的某些东西正在崩溃 . 它是什么?

1 回答

  • 0

    javac 不知道如何推断其中某些方法的泛型类型 .

    assertThat 需要一个值和该类型的 Matcher . 你必须明确

    Assert.assertThat(data, Matchers.<Map<String, String>> hasItem(Matchers.hasKey("x")));
    

    虽然这应该在Java 8中没有显式类型参数的情况下工作 .

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