$ yarn add --dev typescript tslint tslint-microsoft-contrib jest ts-jest @types/jest { "devDependencies": { ... "typescript": "^2.4.2" }, "scripts": { "start": "npm run build && node dist/app.js", "build": "npm run lint && tsc", "test": "jest --forceExit", "lint": "tslint -c tslint.json -p tsconfig.json --type-check" }, "jest": { "transform": { "^.+\\.ts$": "./node_modules/ts-jest/preprocessor.js"
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