I find this a surprising reaction, just because for so many devs I've known, it's common to keep a "sketchpad" interpreter open to mess about with code ideas. And these are all dedicated TDD folks. Perhaps if the dev(s) in question don't really understand TDD, but I think that's a cultural problem rather than a tooling problem.
In my experience, "getting" TDD is about two main things. First, internalizing what to test & why to test. (Fortunately, we've got a lot of help these days on the "how to test" front.) Second, having that moment when having tests makes your life-as-developer easier, or perhaps just possible. (Re: "possible", I recently upgraded a mature, legacy Rails 2.3 app to Rails 4.2. My blessings upon the devs prior to me who saw fit to create a comprehensive and well-maintained test suite. Without that, there would have needed to be a "throw it away and start afresh" discussion. Perhaps even project cancellation.)
In my experience, "getting" TDD is about two main things. First, internalizing what to test & why to test. (Fortunately, we've got a lot of help these days on the "how to test" front.) Second, having that moment when having tests makes your life-as-developer easier, or perhaps just possible. (Re: "possible", I recently upgraded a mature, legacy Rails 2.3 app to Rails 4.2. My blessings upon the devs prior to me who saw fit to create a comprehensive and well-maintained test suite. Without that, there would have needed to be a "throw it away and start afresh" discussion. Perhaps even project cancellation.)