rule-testing

name	rule-testing
description	Middle Earth testing baseline guidelines (unit tests with Jest)

Rule testing

Apply this rule whenever work touches:

• **/*.spec.ts
• **/*.spec.tsx
• **/*.test.ts
• **/*.test.tsx

Testing (Middle Earth)

Unit tests (Jest)

• Tests live in __tests__/ folders within the same directory as source files.
• Filename pattern: *.spec.ts(x).
• Use framework-specific testing libraries (e.g., Testing Library for React).
• Use shared testing helpers when available; keep tests short and behavior-focused.
• Aim for 100% coverage where feasible; write tests that target behavior, not implementation details.

Fixtures and data

• Use faker for generating random inputs where helpful.
• Prefer deterministic assertions over random expected values.

Mocking

• Prefer jest.mock for external modules and jest.spyOn for side effects.
• Use table-driven tests with it.each for input/output matrices.

Assertions

• Prefer expect.objectContaining/not.objectContaining for partial assertions.
• Disallow .only (lint rule enabled) and skipped tests except when justified.

Running tests

# Test a specific project
pnpm nx test <project-name>

# Test all projects
pnpm nx run-many --target test