Question

I am using Moq (which I am very new too as well as TDD period). And I wanted to Moq up an instance of my main Winforms form so I could test a few methods on there. Is this possible? Its constructor takes an object of Assembly().

I was trying the following attempts unsuccessful:

var mockMainForm = new Mock<MainForm>();
mockMainForm.Setup(x => x.Assembler).Returns(new Assembly());
return mockMainForm.Object;

But I can’t access any properties or methods on this object once it is returned. Is this possible to do?

But I get errors that ( failed: System.ArgumentException : Expression is not a method invocation: x => x.Assembler
at Moq.ExpressionExtensions.ToMethodCall(LambdaExpression expression))

Answer 1

Mocking using Moq will only mock the interfaces and virtual methods of a class. Assembler property needs to be defined as virtual.

In any case Mocking a Windows Form is not a good mocking – it has a big bag of WIN32 stuff which make your tests brittle. If you need to unit test and mock a form, create an interface that your form needs to implement and mock that for objects that need to interact with your form.

public interface IHasAssembler
{
    Foo Assembler {get; set;}
}

public class MyForm : IHasAssembler
{
     //
}

then mock the interface and not the form:

Mock<IHasAssembler> myMock = new Mock<IHasAssembler>();