Context
I have an nx workspace set up with a node library and jest as testing framework, which uses Typescript by default to write tests. Within that library I import a function from the Firebase admin node SDK via the ES2015 module import syntax: import { getFirestore } from "firebase-admin/firestore";
When I run the tests, I get a longer error from Jest telling me, that it does not work that way with ES6 modules:
Jest failed to parse a file. This happens e.g. when your code or its dependencies use non-standard JavaScript syntax, or when Jest is not configured to support such syntax.
Out of the box Jest supports Babel, which will be used to transform your files into valid JS based on your Babel configuration.
By default "node_modules" folder is ignored by transformers.
Here's what you can do:
• If you are trying to use ECMAScript Modules, see https://jestjs.io/docs/ecmascript-modules for how to enable it.
• If you are trying to use TypeScript, see https://jestjs.io/docs/getting-started#using-typescript
• To have some of your "node_modules" files transformed, you can specify a custom "transformIgnorePatterns" in your config.
• If you need a custom transformation specify a "transform" option in your config.
• If you simply want to mock your non-JS modules (e.g. binary assets) you can stub them out with the "moduleNameMapper" config option.
You'll find more details and examples of these config options in the docs:
https://jestjs.io/docs/configuration
For information about custom transformations, see:
https://jestjs.io/docs/code-transformation
Details:
/home/pascalbe/repos/tryout/jest-typescript-es6-imports/node_modules/firebase-admin/lib/esm/firestore/index.js:1
({"Object.<anonymous>":function(module,exports,require,__dirname,__filename,jest){import mod from "../../firestore/index.js";
^^^^^^
SyntaxError: Cannot use import statement outside a module
However, when I import ES6 modules in an nx Angular library (import { CommonModule } from '@angular/common';), I do not see these kind of errors when running tests.
Find a sample repository here on GitHub.
Related Questions
I do not really get how all the tools play together: @nrwl/jest, jest, typescript, babel and I also did not understand how to get it to work from the jest guide on ES modules.
- Why does one work and the other does not?
- What can I do to get the node library test working?