Install Testing Dependencies

Run npm install with Jest, ts-jest, testing libraries, and supertest. These provide the foundation for reliable unit and integration tests.

Configure Jest with 80% Coverage Thresholds

Create jest.config.ts with coverageThreshold set to 80% for branches, functions, lines, and statements. Use collectCoverageFrom to target source files and exclude tests and bootstrap code.

Add Test Scripts to package.json

Create test and test:coverage scripts that run Jest locally and in CI. This ensures coverage checks are enforced automatically.

Write Failing Tests First

Before asking AI for implementation, write a test that describes the behavior you want. Be specific about inputs, outputs, and edge cases.

Ask AI to Make Tests Pass

Show the failing test to the AI and ask it to write code that makes the test pass. The test becomes the specification the AI must satisfy.

Run Coverage Check and Merge

Execute test:coverage before merging. If coverage drops below 80%, the build fails. No override, no exceptions — the gate is automatic.

AI generates plausible code fast. Tests are the only signal that it's actually correct. Here's how to set up Jest, coverage thresholds, and CI gates before you touch a single line of AI-generated code.

Ai-coding

Don't Write a Line of AI Code Until Your Tests Are Green