Fake template method in MS Fakes Framework

Question

I have an interface like this:

public interface IConfigManager {
    T GetSetting<T>();
}

On test project, I add fake for above dll, but cannot write fake method for it. Open the generated code, it looks like:

public class StubIConfigManager : StubBase<IConfigManager>, IConfigManager
{
    // Summary:
    //     Sets stubs of GetSetting()
    public void GetSettingOf1<T>(FakesDelegates.Func<T> stub);
}

Because GetSettingOf1 was not define as a delegate so I can use lambda expression to fake. How can I fake it?

Answer 1

Because the method is generic, a single delegate cannot suffice. One delegate cannot be both Func<string> and Func<int>. The method you're seeing allows you to pass in the delegate for a specific type, which is probably stored in a dictionary internally (from my attempts to replicate Fakes' stub behavior).

So, just pass in the delegate you'd normally assign to the property into the GetSettingOf1 method. This is really just a way to allow a generic method to have a stub implementation for any number of types rather than just one.

Example:

var configManager = new StubIConfigManager();
configManager.GetSettingOf1(() => "TestString");
configManager.GetSettingOf1(() => 23);

var stringResult = configManager.GetSetting<string>();
var intResult = configManager.GetSetting<int>();

Assert.AreEqual("TestString", stringResult);
Assert.AreEqual(23, intResult);

Clearly this example is not a test you should write, because Fakes works, but it should get the point across.