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Jest Testing

Testing & Quality
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Expert Jest testing framework for JavaScript/TypeScript unit and integration testing

QUICK START

How to use this skill

Bring this guide into your coding agent with a prompt tailored to the tool you use.

  1. Open your project in Codex.
  2. Copy the prompt below and paste it into your agent.
  3. Review the proposed files and risks before you approve installation.
Prompt to paste
I want to install this Agent Skill for this project in Codex.

Source SKILL.md: https://github.com/a5c-ai/babysitter/blob/HEAD/library/specializations/qa-testing-automation/skills/jest-testing/SKILL.md

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Jest Testing Skill

Overview

This skill provides expert-level capabilities for Jest-based testing, enabling comprehensive unit testing, snapshot testing, and integration with React Testing Library.

Capabilities

Test Execution

  • Configure Jest for various project types (Node, React, TypeScript)
  • Execute tests with coverage collection
  • Parallel test execution configuration
  • Watch mode and selective test running

Unit Testing

  • Write unit tests with proper mocking
  • Configure custom matchers and test utilities
  • Mock module resolution and timer handling
  • Handle async testing patterns

Snapshot Testing

  • Configure and manage snapshot tests
  • Handle snapshot updates and reviews
  • Implement inline snapshots

Coverage Analysis

  • Coverage report generation and analysis
  • Configure coverage thresholds
  • Identify uncovered code paths

React Integration

  • Integration with React Testing Library
  • Component testing patterns
  • Hook testing utilities

Target Processes

  • automation-framework.js - Test framework setup
  • mutation-testing.js - Test quality assessment
  • continuous-testing.js - CI/CD integration
  • shift-left-testing.js - Early testing integration

Dependencies

  • jest - Test runner
  • @testing-library/react - React testing utilities
  • ts-jest - TypeScript support (optional)

Usage Example

{
  kind: 'skill',
  skill: {
    name: 'jest-testing',
    context: {
      action: 'execute-tests',
      testPath: 'src/**/*.test.ts',
      coverage: true,
      coverageThreshold: {
        global: { branches: 80, functions: 80, lines: 80 }
      }
    }
  }
}

Configuration

The skill respects jest.config.js or jest.config.ts in the project root and can override settings as needed.