Testing Standards v.1.0.2

Instruction file imported from Jubblin/matterbridge-camera (.github/instructions/testing/unit-tests.instructions.md). Copyright stays with the author.

Testing Standards for Unit Tests

1. Test Framework

• Use Jest (with ts-jest) or Vitest as the testing framework for all unit tests.
• Jest is available in the repository when the file jest.config.js exists.
• Vitest is available in the repository when the file vite.config.ts exists.
• Avoid using both Jest and Vitest in the same project to prevent conflicts. When both are available, prefer Vitest for new tests and consider migrating existing Jest tests to Vitest over time.
• Jest tests live adjacent to the code being tested with a .test.ts suffix or in test folders. Follow the existing convention in the repository for test file placement.
• Vitest tests live adjacent to the code being tested with a .test.ts suffix or in vitest folders. Follow the existing convention in the repository for test file placement.
• Ensure that tests are written in TypeScript and follow the ESM module format.

2. Test Structure

• Organize tests in file name *.test.ts adjacent to the code being tested.
• Use describe blocks to group related tests and test blocks for individual test cases.

3. Test Naming

• Use descriptive test names that clearly indicate the behavior being tested.
• Follow the format: should [expected behavior] when [condition].

4. Test Data

• Use small, deterministic test data to ensure tests are reliable and easy to understand.

5. Test Coverage

• Aim for high test coverage, but prioritize meaningful tests over achieving 100% coverage.

6. Mocking with Jest

• If using Jest, use jest.unstable_mockModule for mocking dependencies in ESM modules.
• If using Jest, avoid using jest.mock as it is not compatible with ESM modules.

7. Running Tests

• Run the relevant full test unit from start to finish rather than assuming isolated single-test execution is reliable.
• If only one test framework is installed, use npm run test -- yourTest.test.ts or npm run test:coverage -- yourTest.test.ts when the touched area can be validated by running the full relevant test file.
• When both Jest and Vitest are installed, use npm run test -- yourTest.test.ts for Jest or npm run test:vitest -- yourTest.test.ts for Vitest.
• Use the existing tasks.json test tasks for areas that require grouped test files, custom coverage targets, or custom ignore-pattern handling.
• Avoid running all tests unnecessarily to save time and tokens.

8. Test Assertions

• Use appropriate Jest or Vitest matchers for assertions (e.g., toBe, toEqual, toThrow).
• Ensure that assertions are clear and directly related to the behavior being tested.

9. Performance

• Avoid optimization in tests; focus on correctness and clarity.
• Use simple loops and structures in tests to maintain readability and performance.
• Avoid complex setups that may slow down test execution unless necessary for the behavior being tested.
• Prefer simple test cases that are easy to understand and maintain over complex ones that may be difficult to debug.
• Some tests in this repo are intentionally structured as multi-step flows, where state persists across successive steps within a single test unit. Run those test units in full, and keep each test unit isolated from other test units.