Moles vs. JMockit Comparison

Overview

This document compares two similar test double injection frameworks: JMockit for Java and Moles for C#.   We created a set of use cases that capture most/many of the things programmers have to do when unit testing code with test doubles.   We then attempted to create a test case in each framework to demonstrate each use case.

The JMockit test cases can be found in our JMockit Evaluation.   If you're unfamiliar with JMockit, you may want to start with our JMockit: The Basics.

The Moles test cases can be found in our Moles Evaluation.   If you're unfamiliar with Moles, you may want to start with our Pex & Moles: The Basics.   Pex is a complimentary framework for parameterized unit testing, but since there is no Pex equivalent for JMockit, we do not cover Pex outside of that document.

The result of this document summarizes the results of both evaluations and draws some higher-level conclusions on their relative merits.

Evaluation Results

Our common set of use cases as well as the ability to achieve each use case with JMockit and Moles is summarized in this table.

Similarities

Differences

    [TestClass]
    public class ClassTest02
    {
        [TestMethod]
        [HostType("Moles")]
        public void test()
        {
            MDependency02.AllInstances.generate = _ => 123;
            
            Class02 clazz = new Class02();

            Assert.AreEqual(2 * 123, clazz.generate());
        }
    }

public class ClassTestAlternative {
    @Test
    public void testIt() {
        new MockUp<Dependency>() {
            @Mock
            public int generate() {
                return 123;
            }
        };


        Class clazz = new Class();

        assert 123 * 2 == clazz.generate();
    }
}

   @Test
   public void doSomethingHandlesSomeCheckedException() throws Exception
   {
      new Expectations() {
         DependencyAbc abc;

         {
            new DependencyAbc();

            abc.intReturningMethod(); result = 3;

            abc.stringReturningMethod();
            returns("str1", "str2");
            result = new SomeCheckedException();
         }
      };

      new UnitUnderTest().doSomething();
   }

Conclusion