Test-Driven Development is about writing a test first, then the code that satisfies the test. Or... is it? Classic TDD has been crucial in my growth as a developer; and yet, as I started using F# more and C# less, my coding practices have evolved dramatically.Nowadays, I barely test first, but spend my days in the scripting environment. In this talk, I will examine how I used to code, and how I write code in F# today, in a style I consider very much inspired by TDD; I will also discuss how exploring two paradigms (C# and F#) lead me to re-examine my beliefs and practices.