Master Test-Driven Development with deterministic red-green-refactor workflows, test-first feature delivery, bug reproduction through failing tests, behavior-focused assertions, and refactoring safety; use when implementing new functions, changing APIs, fixing regressions, or restructuring code under test.
Does it follow best practices?
Evaluation — 86%
↑ 1.05xAgent success when using this tile
Validation for skill structure
Establish and follow a consistent pattern for test file location and naming. Developers should instantly know where to find tests for any code.
Incorrect (inconsistent structure):
src/
services/
userService.ts
tests/
userService.spec.ts
models/
user.ts
tests/
models/
user.test.ts
spec/
integration/
user_tests.js
__tests__/
userStuff.tsCorrect (consistent co-located tests):
src/
services/
userService.ts
userService.test.ts # Unit tests next to source
models/
user.ts
user.test.ts
components/
UserProfile.tsx
UserProfile.test.tsx
tests/
integration/ # Integration tests separate
user-registration.test.ts
checkout-flow.test.ts
e2e/ # E2E tests separate
user-journey.test.tsAlternative (mirror structure):
src/
services/
userService.ts
models/
user.ts
tests/
unit/
services/
userService.test.ts # Mirrors src/ structure
models/
user.test.ts
integration/
user-registration.test.tsNaming conventions:
*.test.ts or *.spec.ts - pick one, use consistentlyuserService.ts → userService.test.tscheckout-flow.test.tsReference: Jest Configuration - testMatch
Install with Tessl CLI
npx tessl i pantheon-ai/test-driven-development@0.2.4evals
scenario-1
scenario-2
scenario-3
scenario-4
scenario-5
references