Use mock.Provide() to Setup a delegate factory, used in the SUT constructor

Question

I am trying to test the behavior of a class, when it's passed one stub object via a delegate factory. I made a version of the test in which all the class's dependencies (except the factory) are passed as Mock objects and it works as supposed to. Now I am trying to use AutoMock to get the container to automatically create the mocks.

I am having issues passing concrete values for the delegate factory in the constructor in ClassUnderTest using mock.Provide(). (like this comment suggests)

Class that I am testing:

public ClassUnderTest
{
 private readonly firstField;
 private readonly Func<string, ISecondField, IThirdField, IResultField> resultFieldFactory;
 private int someCounter = -1;

 public ClassUnderTest(IFirstField firstField, Func<string, ISecondField, IThirdField, IResultField> resultFieldFactory )
 {
  this.firstField = firstField;
  this.resultFieldFactory= resultFieldFactory;
 }

 public methodToTest()
 {
  IResultField resultField = resultFieldFactory(someString, secondFieldValue, thirdFieldValue);
  resultField.AddToList();
 }
}

Business logic module :

public class BusinessLogicModule: Module
{
//some other things  that work

builder.RegisterType<ClassUnderTest>().As<IClassUnderTest>();
builder.RegisterType<SecondField>().As<ISecondField>();
builder.RegisterType<ThirdField>().As<IThirdField>();
builder.RegisterType<ResultField>().As<IResultField>();

}

Test class:

[TestClass]
public class TestClass()
{
 private IFirstField firstField;
 private Func<string, ISecondField, IThirdField, IResultField> funcToTriggerIResultFieldFactory;


 [TestInitialize]  
 public void Setup()
 {
  this.firstField= Resolve<IFirstField>();
  this.secondField= Resolve<ISecondField>();
  this.funcToTriggerIResultFieldFactory = Resolve<Func<string, ISecondField, IThirdField, IResultField>>();
 }


 [TestMethod]
 public void testMethodWithAutoMock()
 {
  using (var automock = AutoMock.GetLoose())
  {
    //trying to setup the SUT to get passed a "concrete" object
    autoMock.Provide(funcToTriggerIResultFieldFactory(stringValue, secondFieldValue, thirdFieldValue)); 

    var sut = autoMock.Create<IClassUnderTest>;

    sut.MethodToTest();
    //asserts
   }
 }

}

I would be grateful for any indication on what I am doing wrong. What am I missing? How could it be fixed? Is it a simple syntax fix or is something wrong with my approach to this test?

Thanks in advance for your time.

Usually you use mock libraries to mock out the dependencies, not try and add mocks to a DI container because there are too many moving parts. Your tests should be very specific to that class, so you would only need to have a few (if any) mocks set up — Callum Linington, Aug 22 '16 at 13:17
Shouldn't it be autoMock.Create instead of IClassUnderTest ? What's the actual problem? Are you getting a compilation or an execution-time error? — suwik, Aug 22 '16 at 13:33
So I changed it to " autoMock.Create " . I get a System.NullReferenceException when I call sut.MethodToTest(). resultFieldFactory(someString, secondFieldValue, thirdFieldValue) — M.Tach, Aug 22 '16 at 13:58

score 1 · Answer 1 · answered Nov 01 '16 at 00:11

In your example, when you call autoMock.Provide() you are not passing in you factory function, but you are invoking the factory function and passing in the result (IResultField). To fix this, call

autoMock.Provide(funcToTriggerIResultFieldFactory);

Here is a full example of registering a function with the auto mocking container.

Use mock.Provide() to Setup a delegate factory, used in the SUT constructor

1 Answers1