mocha-skill

name mocha-skill description Generates Mocha tests in JavaScript with Chai assertions and Sinon mocking. Use when user mentions "Mocha", "Chai", "sinon", "describe/it (not Jest)". Triggers on: "Mocha", "Chai", "sinon", "mocha test". languages ["JavaScript","TypeScript"] category unit-testing license MIT metadata {"author":"TestMu AI","version":"1.0"} Mocha Testing Skill Core Patterns Basic Test with Chai const { expect } = require ( 'chai' ); describe ( 'Calculator' , () => { let calc; beforeEach ( () => { calc = new Calculator (); }); it ( 'should add two numbers' , () => { expect (calc. add ( 2 , 3 )). to . equal ( 5 ); }); it ( 'should throw on divide by zero' , () => { expect ( () => calc. divide ( 10 , 0 )). to . throw ( 'Division by zero' ); }); }); Chai Assertions expect (value). to . equal ( 5 ); expect (arr). to . have . lengthOf ( 3 ); expect (obj). to . have . property ( 'name' ); expect (str). to . include ( 'hello' ); expect (fn). to . throw ( Error ); expect (arr). to . deep . equal ([ 1 , 2 , 3 ]); expect (obj). to . deep . include ({ name : 'Alice' }); Sinon Mocking const sinon = require ( 'sinon' ); describe ( 'UserService' , () => { let sandbox; beforeEach ( () => { sandbox = sinon. createSandbox (); }); afterEach ( () => { sandbox. restore (); }); it ( 'fetches user from API' , async () => { const stub = sandbox. stub (api, 'get' ). resolves ({ name : 'Alice' }); const user = await userService. getUser ( 1 ); expect (user. name ). to . equal ( 'Alice' ); expect (stub. calledOnce ). to . be . true ; }); }); Async Testing it ( 'should fetch data' , async () => { const data = await fetchData (); expect (data). to . have . property ( 'id' ); }); it ( 'callback style' , ( done ) => { fetchData ( ( err, data ) => { expect (err). to . be . null ; done (); }); }); Anti-Patterns Bad Good Why Missing done() Use async/await Hanging tests No sandbox sinon.createSandbox() Stubs leak Arrow in describe Regular function for this.timeout() Context Quick Reference Task Command Run all npx mocha Watch npx mocha --watch Grep npx mocha --grep "login" Timeout npx mocha --timeout 10000 Recursive npx mocha --recursive Setup: npm install mocha chai sinon --save-dev Deep Patterns → reference/playbook.md § Section Lines 1 Production Configuration mocharc, NYC coverage, TypeScript 2 Testing with Chai + Sinon Stubs, spies, assertions 3 Advanced Sinon Patterns Fake timers, nock HTTP, sequential 4 Async Patterns Promise, await, callback, events 5 Hooks & Test Organization Lifecycle, nesting, grep tags 6 Custom Reporters & Plugins Reporter class, root hooks 7 Express/API Testing Supertest integration 8 CI/CD Integration GitHub Actions, services 9 Debugging Quick-Reference 10 common problems 10 Best Practices Checklist 13 items