Testing vs Design · both proven

test-driven-development vs vercel-react-view-transitions

Both skills were run through Claude twice: once on a fixed brief without the skill, once with it. The briefs differ because each is written for the job the skill claims to do, so compare each skill against its own baseline, then decide which difference matters for your work. They are in different categories, so this is a choice of job, not a head-to-head on the same job.

test-driven-development

Use when implementing any feature or bugfix, before writing implementation code

Category: Testing
Source: obra/superpowers
License: MIT
Proof model: claude-opus-5-5
Brief: “Implement a function that parses a cron expression (the standard five fields) and returns the next run time after a given date, in TypeScript. Present the work as a single HTML page with two columns: the test file on the left and the implementation on the right, each in a code block, with a short note at the top on the order you did things in and anything you decided not to support.”
Skill commit: bb92a77

Without the skillWith test-driven-development

⇆

Without, runWith test-driven-development, run3 independent runs per side, none selected by hand.

Download the with-skill page

vercel-react-view-transitions

Guide for implementing smooth, native-feeling animations using React's View Transition API (`<ViewTransition>` component, `addTransitionType`, and CSS view transition pseudo-elements). Use this skill whenever the user wants to add page transitions, animate route changes, create shared element animations, animate enter/exit of components, animate list reorder, implement directional (forward/back)…

Category: Design
Source: vercel-labs/agent-skills
License: Not stated
Proof model: claude-opus-5-5
Brief: “Build a photo gallery for a small travel photographer as a single HTML page using React from a CDN: a grid of twelve photos drawn with inline SVG or CSS gradients, where clicking a photo smoothly expands it into a detail view with a caption and location, and going back animates it into its place in the grid. Filtering the grid by country should animate the reordering too.”
Skill commit: 063bee9

Without the skillWith vercel-react-view-transitions

⇆

Without, runWith vercel-react-view-transitions, run3 independent runs per side, none selected by hand.

Download the with-skill page

We don’t pick a winner for you: the pages are the evidence. Both proofs can be repeated with the brief, model and commit shown above. See alternatives to test-driven-development or alternatives to vercel-react-view-transitions.