GuitarEasy is a web application that converts guitar tabs via ChatGPT into playable notation, using alphaTab for rendering and a built-in MIDI player for practice. Users can upload or select from bundled example scores, with all data stored locally in the browser.
This article explains how to document test cases using 'caseshots'—files combining inputs and expected outputs in problem-specific notation—to make test failures more intelligible and enable reuse across testing, code review, and production inspection. It illustrates this approach through a portfolio levelling problem where new investment money must be allocated across funds to reach target allocations.