Jest / Ts-Jest / Babel : Debug Failure. False expression: Output generation failed

Question

With TypeScript 2.8, we have now the possiblity to generate .d.ts only from source files. So my tsconfig.json becomes :

{
  "compilerOptions": {
    "allowSyntheticDefaultImports": true,
    "module": "commonjs",
    "target": "es5",
    "lib": ["ES6","ES2017","ESNext"],
    "downlevelIteration": true,
    "moduleResolution": "node",
    "declaration": true,
    "emitDeclarationOnly": true,
    "declarationDir": "./lib"
  },
  "exclude": [
    "node_modules"
  ],
  "include": [
    "src/**/*"
  ],
  "strict": true
}

The problem is the build is broken with that (https://travis-ci.org/jy95/mediaScan/jobs/359573738). My repo : https://github.com/jy95/mediaScan/tree/prettier

Any ideas how to fix it ?

My jest.config.js :

// jest.config.js
module.exports = {
    verbose: true,
    "moduleFileExtensions": [
        "ts",
        "tsx",
        "js"
    ],
    "transform": {
        "^.+\\.tsx?$": "ts-jest"
    },
    "testMatch": [
        "<rootDir>/__tests__/**/*.(ts|tsx|js)"
    ],
    "testPathIgnorePatterns": ["<rootDir>/node_modules/", "<rootDir>/__tests__/__helpers__/"],
    "collectCoverage": true
};

Thanks

Answer 1

I've experienced similar issue when was switching jest to process .js files with ts-jest instead of babel-jest.

Error happens (according to stacktrace) at getConstructorDefinedThisAssignmentTypes in typescript.js. And is most likely caused by incorrect or missing types. Add some breakpoints or log types there/declarations to see what exactly is failing.

You can try to upgrade typescript to the latest version, it might give more valuable error message, and try to tsc --noEmit to see if there are some loose ends with your types.

Also sometimes npx jest --clearCache helps