Behavior-Driven Development (bdd)

The distinction that matters

Spec-style test-first is about ordering and syntax. Behavior-driven is about the collaboration design being discovered and defended by executable examples. Writing describe/it first is a means; it is not the goal. The goal is four properties of what you produce:

1. A spec so strong a lazy hack — or a lying mock — cannot pass it. (defensible)
2. Every edge, malformed input, AND collaborator-failure path explicitly decided, never accidental. (decided)
3. A collaboration design that changed when the mocking got painful. (design feedback)
4. Specs that read as living documentation of the behavior, in the domain's language. (living documentation)

If you wrote pretty describe blocks but produced none of these, you did test-first, not behavior-driven. This skill produces these results in a single pass, by attacking your own work with things you actually run — because reasoning about whether your mocks tell the truth is unreliable, but running a cheat and a contract test against them is not.

Stance: mockist / outside-in