Assert better.
Ship confident.
Test your testing instincts with quick-fire challenges, and study patterns across unit tests, mocking, async, components, and more.
free · no signup · 7 categoriestest-results.log
✓
unit
validates email format
pass
✓
unit
rejects empty input
pass
✓
integration
creates user in db
pass
✗
component
renders login form
fail
✓
async
retries on timeout
pass
Two ways to level up
A pattern quiz and a reference library.
Play
Pick the better testing pattern in 10 side-by-side code challenges. Daily and weekly seeds included.
Learn
Patterns across 7 categories. Each shows the fragile approach, the resilient one, and why it matters.
Bug Hunt
Minesweeper meets QA. Reveal safe modules and flag the bugs before they crash production.
Can't Maintain
React component API design. Props, composition, and patterns.Can't Resize
Responsive design patterns. Media queries, flexbox, grid, and viewport units.Can't Type
TypeScript patterns. Generics, narrowing, utility types, and common mistakes.Can't Orchestrate
Container orchestration patterns. Docker, Kubernetes, CI/CD, and Helm.Can't SEO
SEO best practices for Next.js. Meta tags, Open Graph, structured data, and more.Can't UX
UX design patterns. Typography, spacing, color, hierarchy, layout, and forms.Can't Explode
Chemistry challenges. Molecular stability, acid strength, bond energy, and electronegativity.Can't Branch
Git best practices. Commits, branches, merges, PRs, hooks, and repository management.Can't Query
API endpoint patterns. REST, GraphQL, WebSockets, auth, and error handling.Can't Game
Game development patterns. Game loops, input, physics, rendering, AI, shaders, and netcode.Can't Ticket
Agile ticket craft. User stories, acceptance criteria, story points, and splitting work the team can ship.