QABattle

BDD & TDD / Scenario

Boss: The Legacy Rescue

A 400-line pricing function with no tests, a hidden clock, a global config, and a live bug. Change its behavior without burning the shop down.

Difficulty
Boss
Format
Scenario
Points
300
Estimate
18 min

// MISSION BRIEF

Your Mission

Finance wants tax rounding changed in calculateOrderTotal, a 400-line legacy function with zero tests, direct DB calls, Date.now() scattered through it, and a global config object. Last "quick change" here caused a refund incident.

Plan the rescue like a professional: safety net first, seams second, behavior change last.

Scoring: boss fight. Five weighted decisions; the opening move counts double.

// FIRST CONTACT

Battle teaser

First artifact

pricing.js (shape of the beast)

Your first move, before touching a single line:

  1. ARewrite the function from the spec; the old code is unsalvageable
  2. BCharacterization (golden master) tests: feed a broad matrix of real-ish orders through the CURRENT code and pin its exact outputs, bugs included
  3. CFix the .005 rounding bug immediately, it is a known defect
  4. DRefactor the 400 lines into clean functions first, tests will be easier after
Answers, scoring, hints, and the full battle stay sealed.

// SKILL TAGS

legacy-codetddcharacterization-testsrefactoring