namespace TestLibrary.Library
{
public class AnotherEventTracker
where TDelegate : class
{
public static implicit operator TDelegate(AnotherEventTracker tracker)
{
return tracker.Delegate;
}

public static implicit operator bool(AnotherEventTracker tracker)
{
return tracker.Verify();
}

private int _callCount;
private List<Func> _checks;

public AnotherEventTracker()
{
_checks = new List<Func>();

var delegateMeta = typeof(TDelegate).GetMethod("Invoke");

var delegateParams = delegateMeta
.GetParameters()
.Map(param => param.ParameterType)
.Prepend(GetType())
.ToArray();

var invokedMethod = GetType().GetMethod("Invoked", BindingFlags.NonPublic | BindingFlags.Instance | BindingFlags.Public);
var dynamicHandler = new DynamicMethod("", delegateMeta.ReturnType, delegateParams, GetType(), true);
var generator = dynamicHandler.GetILGenerator();

generator.Emit(OpCodes.Ldarg_0);
generator.Emit(OpCodes.Call, invokedMethod);
generator.Emit(OpCodes.Ret);
Delegate = dynamicHandler.CreateDelegate(typeof(TDelegate), this) as TDelegate;
}

public TDelegate Delegate
{
get;
private set;
}

public AnotherEventTracker WasCalled()
{
_checks.Add(() => _callCount > 0);
return this;
}

public AnotherEventTracker Once()
{
return Exactly(1);
}

public AnotherEventTracker Twice()
{
return Exactly(2);
}

public AnotherEventTracker Exactly(int numberOfTimes)
{
_checks.Add(() => _callCount == numberOfTimes);
return this;
}

public bool Verify()
{
return _checks.TrueForAll(func => func());
}

// called via the dynamic method
private void Invoked()
{
_callCount++;
}
}
}