Mocking Delegate Factories in Service Libraries with Autofac and Moq - moq

Question

I have a simple console application which uses Autofac as IoC container.
class Program
{
static IContainer container;
static void Main(string[] args)
{
container = Configure();
Run();
}
private static void Run()
{
using (var scope = container.BeginLifetimeScope())
{
var t = scope.Resolve<ITest1>();
var s = t.TestMethod1("");
Console.WriteLine(s);
}
}
private static IContainer Configure()
{
var builder = new ContainerBuilder();
builder.RegisterType<TestClass1>()
.As<ITest1>();
builder.RegisterType<TestClass2>()
.As<ITest2>();
return builder.Build();
}
}
The application calls the method "TestMethod1" in "TestClass1".
public interface ITest1
{
string TestMethod1(string s);
}
public class TestClass1 : ITest1
{
ITest2 f;
public TestClass1(Func<ITest2> test2Factory)
{
f = test2Factory();
}
public string TestMethod1(string s)
{
var r = string.Empty;
r = f.TestMethod2(s);
r += ":TestMethod1";
return r;
}
}
TestClass1 has a dependency on TestClass2 which declares a delegate factory for Autofac to use with the TestClass1 constructor.
public interface ITest2
{
string TestMethod2(string s);
}
public class TestClass2 : ITest2
{
public delegate TestClass2 Factory();
public virtual string TestMethod2(string s)
{
return ":TestMethod2";
}
}
This all works as expected - Autofac resolves the TestClass2 dependency, and I get the output ":TestMethod2:TestMethod1".
Now I want to mock TestClass2 using Moq and the Autofac.Extras.Moq extensions. I add the following method to the console application, and call it from the Program Main method.
private static void Test()
{
using (var mock = AutoMock.GetLoose())
{
mock.Mock<TestClass2>()
.Setup(t => t.TestMethod2(""))
.Returns(":NOT_TEST_METHOD2");
var s = mock.Create<TestClass1>();
var r = s.TestMethod1("cheese");
Console.WriteLine(r);
}
}
Now I get the output ":TestMethod1" when I expect ":NOT_TEST_METHOD2:TestMethod1". It seems the mock has not been called. This is confirmed when I step through the code.
I have also tried resolving the mock using mock.Provide(), as has been suggested elsewhere (see below). Still no luck.
var wc = Moq.Mock.Of<TestClass2>(f => f.TestMethod2("") == ":NOT_TEST_METHOD2");
Func<string, ITest2> factory = x => wc;
mock.Provide(factory);
This seems like a really simple scenario but I've not found a working answer anywhere. Can anyone see what I'm doing wrong?
Thanks for any help!

Answer 1

I don't use the AutoMock support, but I do know my Autofac, so I can give it a shot.
It looks like TestClass1 takes an ITest2 and not a TestClass2 in its constructor, I'm guessing if you switched to this:
mock.Mock<ITest2>()
.Setup(t => t.TestMethod2(""))
.Returns(":NOT_TEST_METHOD2");
...then it might work.

Answer 2

Thanks Travis. Your suggestion didn't work for me, but it made me think about the issue differently and taking a step back made me realise I was looking for a complex solution where one wasn't required. Namely, that only Moq was needed, Autofac AutoMock extensions were not. The following code worked:
private static void Test()
{
Func<ITest2> func = () =>
{
var x = new Mock<ITest2>();
x.Setup(t => t.TestMethod2("")).Returns(":NOT_TEST_METHOD2");
return x.Object;
};
var s = new TestClass1(func);
var r = s.TestMethod1("");
}
The question was answered by this post Using Moq to Mock a Func<> constructor parameter and Verify it was called twice.