Using MOQ to Test Whether a Method Was Called

I use MOQ for my server-side unit testing.  It's pretty easy to get started with and it's always done everything I needed it to do... until recently.

I needed to test whether a method was called with a specific set of parameters.  The result wasn't really important (because the method being called was mocked to do nothing anyway) and the method didn't have a return type so there was no way to validate the results of the method call.  I really just needed to know whether the method was called at all.  It turns out MOQ can do that, too.

The method that needs to be tested:

   1:  public void MethodUnderTest(CustomComplexObject customComplexObject)

   2:  {

   3:      var someLocalVariable = false;

   4:      

   5:      MethodThatShouldBeCalled(customComplexObject.Id, customComplexObject.UserId, someLocalVariable);

   6:      

   7:      /*snip*/

   8:  }

The method that should be called by the method that needs to be tested (this method must be virtual):

   1:  public virtual void MethodThatShouldBeCalled(int id, int userId, bool shouldDoSomethingSpecial)

   2:  {

   3:      if (shouldDoSomethingSpecial)

   4:      {

   5:          /*snip*/

   6:      }

   7:      else

   8:      {

   9:          /*snip*/

  10:      }

  11:  }

The test (an important note is the usage of "CallBase = true"; this won't work unless you include that):

   1:  [TestMethod]

   2:  public void MethodUnderTestShouldCallMethodThatShouldBeCalled()

   3:  {

   4:      // arrange

   5:      // create a new mocked BusinessManager

   6:      // note that this is mocking a concrete object and not an interface

   7:      var moqBusinessManager = new Mock<BusinessManager>{CallBase = true};

   8:      

   9:      // create a test object to pass to MethodUnderTest

  10:      var customComplexObject = new CustomComplexObject

  11:      {

  12:          Id = 123456789,

  13:          UserId = 987654321

  14:      };

  15:      

  16:      // setup the mocked BusinessManager so that MOQ knows what it should keep track of

  17:      moqBusinessManager.Setup(p => p.MethodThatShouldBeCalled(It.IsAny<int>(), It.IsAny<int>(), It.IsAny<bool>()))

  18:          .Verifiable("MethodThatShouldBeCalled was not called");

  19:      

  20:      // act

  21:      // execute MethodUnderTest with the test object

  22:      // note the user of .Object

  23:      moqBusinessManager.Object.MethodUnderTest(customComplexObject);

  24:      

  25:      // assert

  26:      // use MOQ to verify that MethodThatShouldBeCalled was called with the expected parameters

  27:      moqBusinessManager.Verify(p => p.MethodThatShouldBeCalled(123456789, 987654321, false));

  28:  }