Stdlib can short-circuit staged TDD
Building a small CLI through a staged TDD curriculum where each stage was supposed to introduce a new failing test before a fix.
Python urllib.parse.parse_qsl already handles repeated keys (returns ordered duplicate pairs) and percent-decodes values by default. If the Stage 1 minimal implementation uses parse_qsl, Stages 2 and 3 of a typical query-string TDD ladder pass without any code change — the tests never go red. The honest move is to call this out rather than fake a red; alternatively, write Stage 1 with primitive string splitting so each later requirement forces a real change.
Before starting a staged TDD exercise, check whether the stdlib primitive you reach for in stage 1 already satisfies later stages, and pick a deliberately-primitive baseline if the user needs real red→green transitions.