In my C# code I like to leave a "throw new NotImplementedException();" behind if I can't finish something. I'm with some of the other posters though in that I like to leave stuff working at the end of the day.
Otherwise, you are simply leaving a bug that is only discovered at run-time rather than one that is discovered at compile time. Doesn't seem like an improvement to me
And for your information...I do have a test, but it doesn't fail, it returns positive. I search for "NotImplementedException()".