JMockit MockUp for method with private class parameter

Question

I'm writing some unit tests using JUnit and JMockit and need to write a JMockit MockUp for a method that takes an instance of a private enum as an argument. Here's the the class I need to mock:

public class Result {
    //Static constants representing metrics
    public static final Metric AVOIDABLE = Metric.avoidable;
    public static final Metric UNAVOIDABLE = Metric.unavoidable;

    // private enumeration of metric values
    private enum Metric {avoidable, unavoidable};

    public Long getTodayCount(Metric metric) { //<- instance of private enum
        return getValueForKey(metric);
    }
}

depending on the specific Metric given I need to return a different Long value. If the Metric enum were public that would be straightforward enough. Something like:

private static class MockResult extends MockUp<Result> {
    @Mock
    Long getTodayCount(Metric m){ //<-- nope. Metric is private
        if(Result.AVOIDABLE.equals(m)){ //<-- can't call equals either
            return 1234L;    
        } else {
            return 4567L;
        }
    }
}

But since Metric is private is there any way to accomplish this aside from changing Metric to be public? That may end up being the only way to accomplish this, but I'm not the author of the Result class and am not completely familiar with the reasoning behind making Metric private in the first place.

It looks weird that the enum is private, but the constants are pubic. That does not make much sense. — Crazyjavahacking

Crazyjavahacking Crazyjavahacking · Accepted Answer · 2015-02-28T11:18:03

As per documentation:

The @Mock annotation marks those methods in the mock-up class which are meant to provide mock implementations for the corresponding methods (of the same signature) in the mocked class.

If the enum is private, you cannot use it in your unit tests as it will not be visible outside the class. Then you cannot define a proper MockUp.

You have to either make Metric class more visible (at least package private) or mock out the whole Result class.

JMockit MockUp for method with private class parameter

1 Answers