𝗨𝗻𝗶𝘁 𝗧𝗲𝘀𝘁 𝗔𝗜 𝗚𝘂𝗶𝗱𝗲: 𝗭𝗲𝗿𝗼 𝗛𝗮𝗹𝗹𝘂𝗰𝗶𝗻𝗮𝘁𝗶𝗼𝗻

AI often fails at unit testing. It invents methods. It creates wrong mock structures. It uses non-existent imports. This happens because the AI lacks strict context.

You can stop this by using a deterministic system. You must move from guessing to enforcing.

Here is the standard for zero-hallucination unit tests across five major stacks.

The Tech Stack Standard

Pick one library per stack. Do not mix them.

  • Node.js (NestJS/Express): Jest
  • React.js: Vitest + React Testing Library
  • Python: pytest
  • Angular: Jest
  • Laravel: Pest

The Secret: Project-Scoped Rules

Standard prompts are not enough. You need to inject rules directly into your IDE. If you use Cursor, use the .cursor/rules/ directory.

Create specific rule files for each technology:

  • unit-test-global.mdc: Sets the AAA (Arrange, Act, Assert) pattern.
  • unit-test-nestjs.mdc: Enforces TestingModule and jest-mock-extended.
  • unit-test-react.mdc: Mandates user-event over fireEvent.
  • unit-test-python.mdc: Standardizes pytest-mock patterns.
  • unit-test-laravel.mdc: Ensures Pest syntax and Mockery usage.

These files act as a contract. The AI reads them before every single prompt. This prevents hallucinations at the source.

The Unit Test Contract

Every test must follow these five rules:

  • Isolation: Mock all external dependencies. No real DB or HTTP calls.
  • Structure: Use AAA. Always comment your Arrange, Act, and Assert blocks.
  • Naming: Use "should [behavior] when [condition]". Avoid vague names like "test 1".
  • Coverage: Test the happy path, null inputs, error paths, and edge cases.
  • Speed: Each test must run in under 100ms.

Implementation Steps

  1. Set up your library and configuration files.
  2. Create your .cursor/rules/ folder.
  3. Add a CLAUDE.md file at your project root to act as permanent memory.
  4. Set coverage thresholds in your CI pipeline (aim for 80% lines).
  5. Use pre-commit hooks to ensure no untested code enters the repo.

Stop asking AI to write tests. Start telling AI how to write tests.

Source: https://dev.to/bhaumik-viitor/unit-test-ai-guide-zero-hallucination-cross-stack-standard-4mb2

Optional learning community: https://t.me/GyaanSetuAi