test-writer

name	Test Writer
description	Specialized agent for systematic improvement of test coverage from current baseline to ≥80%. Use this skill when writing unit tests for business logic, integration tests for cross-boundary operations, E2E tests for critical user journeys, or achieving ≥80% test coverage target with strategic test prioritization.

Test Writer

This Skill provides Claude Code with specific guidance for improving test coverage systematically.

When to use this skill

• When test coverage is below 80% (current: 16.6%)
• When writing unit tests for business logic (fast, isolated)
• When writing integration tests for cross-boundary operations
• When writing E2E tests for critical user journeys (Playwright)
• When prioritizing testing by risk (P0: data loss, P1: user-facing)
• When mocking external dependencies (WebContainer, AI providers)
• When testing edge cases and error states

Instructions

For detailed implementation guidance, refer to: Test Writer Agent

Workflow Integration

This skill follows the testing-test-writing workflow:

1. Coverage Analysis: Identify untested critical paths, calculate coverage metrics, prioritize by risk
2. Test Writing: Write unit tests for business logic, integration tests for boundaries, E2E tests for critical journeys
3. Test Quality: Follow best practices (AAA pattern, descriptive names), mock external dependencies, test edge cases
4. Validation: Run test suite (100% pass rate), measure coverage, ensure no regression

Quality Standards

Test Coverage Target

• ✅ Target: ≥80% coverage (current: 16.6%)
• ✅ Unit Tests: Business logic, utilities, pure functions
• ✅ Integration Tests: Store + component interactions
• ✅ E2E Tests: Critical user journeys (login, file operations, AI chat)

Test Quality

• ✅ AAA pattern (Arrange, Act, Assert)
• ✅ Descriptive test names (should [expected behavior] when [state/context])
• ✅ Mock external dependencies (WebContainer, AI providers)
• ✅ Test edge cases and error states
• ✅ Tests are maintainable and reliable

Test Prioritization Strategy

P0: Critical Paths (Data Loss Risk)

• File system operations (read, write, delete)
• Database operations (IndexedDB CRUD)
• Authentication and authorization
• State persistence and hydration

P1: User-Facing Features

• UI components (critical workflows)
• AI agent interactions
• Workspace switching
• Sync operations

P2: Business Logic

• Data transformations
• Validation logic
• Error handling
• Utility functions

Example Usage

"Write tests for src/lib/state/rag-store.ts to achieve ≥80% coverage"

This will:

1. Analyze current coverage for the store
2. Identify untested critical paths (CRUD operations, state updates)
3. Write unit tests for each action method
4. Write integration tests for store + component interactions
5. Validate with coverage measurement

Validation Commands

# Run test suite
pnpm test

# Measure coverage
pnpm test -- --coverage

# Check coverage report
open coverage/index.html

# Show uncovered lines
pnpm test -- --coverage --reporter=text-summary

Success Criteria

• ✅ Test coverage ≥80% (target)
• ✅ 100% test pass rate
• ✅ All critical paths tested (P0 priority)
• ✅ Edge cases and error states covered
• ✅ Tests are maintainable (clear names, good structure)
• ✅ External dependencies properly mocked