test-specialist_skill

Overview

This skill helps write, debug, and improve tests for JavaScript and TypeScript applications. It combines systematic test patterns (unit, integration, E2E), a five-step bug analysis workflow, and automated coverage analysis to close testing gaps. Use it to raise confidence in releases and reduce regressions through repeatable practices.

How this skill works

The skill inspects code and test suites, suggests focused tests using the AAA pattern, and recommends integration and E2E scenarios for real user flows. It guides a structured bug analysis: reproduce, isolate, find root cause, implement a failing test, fix, and validate. It also uses coverage tooling and scripts to locate untested files and prioritize what to test next.

When to use it

• Adding new features — apply TDD and write failing tests first
• Fixing bugs — reproduce, isolate, add a test that fails, then fix
• Improving test coverage — run coverage analysis and target high-priority files
• Debugging runtime errors, race conditions, or logic bugs
• Testing performance and security concerns before release

Best practices

• Write one behavior per test and use clear, descriptive names
• Keep tests independent and avoid shared mutable state
• Mock external dependencies to keep tests fast and deterministic
• Cover happy paths, edge cases, and error conditions (nulls, boundaries, invalid input)
• Use coverage reports to prioritize critical logic and business paths

Example use cases

• Unit-test a calculation module with parameterized tests for decimals, large numbers, and negatives
• Integration-test an API endpoint with database seed/cleanup and verify persisted state
• Create an E2E scenario that exercises a full user workflow (add item, view list, update total)
• Reproduce a race condition with concurrent operations and write a test asserting final state
• Run find_untested_code.py and analyze_coverage.py to generate a prioritized test plan