Cannot find name 'it' in Jest TypeScript

Question

I try to create an intial setup for Jest in React + TypeScript. I have completed the initial setup and try to check whether the test runs. When I run the test using the command npm test, I am getting the following error:

Cannot find name 'it'. Do you need to install type definitions for a test runner? Try `npm i @types/jest` or `npm i @types/mocha`. 

I have installed the types for Jest as well as removed the types in tsconfig.json, but still I am getting the same error.

{   "compilerOptions": {     "target": "es6",     "lib": ["dom", "dom.iterable", "esnext"],     "allowJs": true,     "skipLibCheck": true,     "esModuleInterop": true,     "allowSyntheticDefaultImports": true,     "strict": true,     "forceConsistentCasingInFileNames": true,     "module": "esnext",     "moduleResolution": "node",     "plugins": [{ "name": "typescript-tslint-plugin" }],     "resolveJsonModule": true,     "isolatedModules": true,     "noEmit": true,     "jsx": "preserve",     "pretty": true,     "baseUrl": "src",     "types": ["jest"],     "typeRoots": ["./src/types"],     "suppressImplicitAnyIndexErrors": true   },   "include": ["src", "node_modules/@types/jest"],   "exclude": ["node_modules"] } `  

Package.json

     "jest": {         "transform": {           ".(ts|tsx)": "ts-jest"         },         "testRegex": "(/__tests__/.*|\\.(test|spec))\\.(ts|tsx|js)$",         "moduleFileExtensions": [           "ts",           "tsx",           "js"         ]       },       "devDependencies": {         "@babel/plugin-proposal-export-default-from": "^7.2.0",         "@types/enzyme": "^3.9.3",         "@types/jest": "^24.0.14",         "enzyme": "^3.10.0",         "gh-pages": "^1.2.0",         "husky": "^2.2.0",         "jest": "^24.8.0",         "node-sass": "^4.11.0",         "prettier": "^1.17.0",         "react-scripts": "2.1.8",         "react-test-renderer": "^16.8.6",         "stylelint": "^9.3.0",         "stylelint-config-recommended-scss": "^3.2.0",         "stylelint-config-standard": "^18.2.0",         "stylelint-order": "^0.8.1",         "stylelint-scss": "^3.1.3",         "ts-jest": "^24.0.2",         "tslint": "^5.16.0",         "tslint-config-prettier": "^1.18.0",         "tslint-plugin-prettier": "^2.0.1",         "tslint-react": "^4.0.0",         "tslint-react-hooks": "^2.1.0"       }  

Answer 1

Install

npm install jest @types/jest ts-jest 

jest.config.js -- at root

 module.exports = {   roots: ['<rootDir>/src'],   transform: {     '^.+\\.tsx?$': 'ts-jest',   },   testRegex: '(/__tests__/.*|(\\.|/)(test|spec))\\.tsx?$',   moduleFileExtensions: ['ts', 'tsx', 'js', 'jsx', 'json', 'node'], } 

tsconfig.json

{     "compilerOptions": {      ...        "types": ["reflect-metadata", "jest"],       "typeRoots": ["./types", "./node_modules/@types"]       ...     },     "exclude": ["node_modules", "**/*.spec.ts", "**/*.test.ts"],     "include": ["./src/**/*.tsx", "./src/**/*.ts"]   }