java参数匹配器的使用无效！需要0个匹配器，记录了1个

Question

虽然这个错误很有描述性，但我还是弄不懂。 对于线路：

    PowerMockito.when(
            mockStringMessageService.lookupString(Matchers.eq("XYZ")))
            .thenReturn(Matchers.eq("XYZ"));

错误是：

[junit] Invalid use of argument matchers!
[junit] 0 matchers expected, 1 recorded:
[junit] -> at com.amazon.kilvish.types.StatusTableTest.setUp(StatusTableTest.java:61)
[junit] 
[junit] This exception may occur if matchers are combined with raw values:
[junit]     //incorrect:
[junit]     someMethod(anyObject(), "raw String");
[junit] When using matchers, all arguments have to be provided by matchers.
[junit] For example:
[junit]     //correct:
[junit]     someMethod(anyObject(), eq("String by matcher"));
[junit] 
[junit] For more info see javadoc for Matchers class.

为什么需要0个匹配者

Answer 1

不能在thenReturn子句中使用匹配器。只需使用字符串文字即可：

PowerMockito.when(
        mockStringMessageService.lookupString(Matchers.eq("XYZ")))
        .thenReturn("XYZ");