public void Execute_ShouldExecuteBehavior(IExecutable<ICustomExtension> testee)
{
var first = new Mock<IBehavior<ICustomExtension>>();
var second = new Mock<IBehavior<ICustomExtension>>();
var extensions = Enumerable.Empty<ICustomExtension>();
testee.Add(first.Object);
testee.Add(second.Object);
testee.Execute(extensions, this.executableContext.Object);
first.Verify(b => b.Behave(extensions));
second.Verify(b => b.Behave(extensions));
}