Aman Deep Gautam Aman Deep Gautam - 6 months ago 37
Java Question

Invalid use of argument matchers! 0 matchers expected, 1 recorded

Although the error is quite descriptive I could not get a hang of it.
For lines:

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


Error is:

[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.


Why are 0 matchers expected?

Answer

You cannot use matchers in the thenReturn clause. Just use the string literal instead:

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