Instruction file imported from bennyskov/HAP (.github/instructions/copilot-testings.instructions.md). Copyright stays with the author.

1. Testing Guidelines

1.1 Structure

• One test file per source file, co-located or in tests/
• Group related tests with describe blocks named after the unit under test
• Test names: "should [do something] when [condition]"

1.2 Coverage Expectations

• All public functions must have at least one test
• Cover: happy path, edge cases, and error scenarios
• Integration tests for external I/O (DB, API, filesystem)

1.3 Mocking

• Mock at the boundary — external services, DBs, network calls
• Use real implementations for pure business logic
• Restore mocks after each test (afterEach)

1.4 Assertions

• One logical assertion per test where practical
• Use specific matchers (.toEqual, .toThrow) over .toBeTruthy
• Test behaviour, not implementation details

1.5 Anti-patterns

• Don't test private methods directly
• Don't use setTimeout or real delays — use fake timers
• Don't share mutable state between tests

1.6 Test Documentation Maintenance

• Keep tests/testsGuide.md up to date whenever new tests are added.
• If an existing test changes scope or intent, update tests/testsGuide.md in the same change.