Is TDD Dead?

On April 23, 2014, David Heinemeier Hansson (DHH) published a blog post titled “TDD is dead. Long live testing.” TDD stands for Test-Driven Development: a practice, popularized by Kent Beck, where you write an automated test describing what code should do before you write the code itself, then make the test pass. The idea of TDD is not up for debate here; only DHH’s argument about it is.

DHH’s claim was not that testing is bad. He is emphatic that automated tests matter. His argument was narrower: that writing tests strictly first, as a rule, had for him turned into what he called “test-first fundamentalism,” which he compared to “abstinence-only sex ed: An unrealistic, ineffective morality campaign”. He wrote, “My name is David, and I do not write software test-first,” and argued that designing code around test-first mocking could produce “test-induced design damage”. The post grew out of his keynote at RailsConf 2014, where he had raised the same concerns.

The part everyone remembers: it stayed kind

What happened next is the reason the story is worth telling. Instead of a flame war, it became a conversation. Martin Fowler, a well-known writer on software design, sent DHH a note, they talked, Kent joined, and the three agreed to hash it out in public. The result was a series of recorded video hangouts called “Is TDD Dead?”, five roughly half-hour episodes running from May 9 to June 4, 2014, each with written minutes.

Martin summed up the origin plainly: “David had a similar discussion with Kent, and Kent suggested that we continue the discussion with all three of us, and make the conversation public”. In the exchange, DHH questioned test-first as a default, Kent defended TDD as one valuable tool among many, and Martin took a context-first middle ground, drawing a line between self-testing code in general and strict test-first TDD specifically. Three people who disagreed sat down, stayed generous, and tried to actually understand each other. Whether TDD is right for you is a call the series deliberately leaves to you, and so does this card.

Related: David Heinemeier Hansson (DHH) · Rails was pulled out of Basecamp