Jest test runs - Cannot find module error

问题

I have been working on a React Typescript repo and have been running into an annoying issue where in jest is not able to resolve imports relative to root dir.

 Cannot find module '~lib/dates' from 'utils.ts'

And this how the import looks like in the component / utils

import { abc } from '~lib/dates';   // this fails to run

If I change this to a relative path jest test runs works as expected

import { abc } from '../../lib/dates';   // this runs as expected

The same path work for some other directories and I am a bit stumped

import { xyz } from '~components/home/constants';   // jest resolves it
import { abc } from '~lib/dates';                     // ERR

I tried including moduleNameWrapper in the jestConfig to see if it jest can resolve the imports correctly but it did not help.

package.json

"jest": {
   ...

   "moduleNameWrapper": {
      "^~(.*)$": "<rootDir>/src/$1"
    }
}

I could for sure update the VS code setting so that auto imports are resolved relatively to the file and not with the root dir but this has been bugging me for a while. It would be great if anyone has any pointers on how best to resolve this.

I am on a monorepo with the following directory structure

repo
  server
  client
    src
       components
       lib
       utils
    package.json

回答1:

Your implementation looks right. But it looks like the option moduleNameWrapper was the wrong option, it's supposed to be moduleNameMapper.

I also have an example as same as you which also uses babel as transplier, it works fine as I added moduleNameMapper. Here is the my example:

Jest configuration:

https://github.com/tmhao2005/lerna-demo/blob/master/packages/helper/jest.config.js

Here is the file for testing:

https://github.com/tmhao2005/lerna-demo/blob/master/packages/helper/src/index.ts https://github.com/tmhao2005/lerna-demo/blob/master/packages/helper/src/index.test.ts

回答2:

forget the ~ character;

first define root directory to jest (i.e. src/);

then import your stuff from that root directory; (e.g. import { abc } from 'lib/dates')

by the way you can always import your stuff from default root without any configuration like this: import { abc } from 'src/lib/dates'

further read if you are using create-react-app jest absolute import

来源：https://stackoverflow.com/questions/63709973/jest-test-runs-cannot-find-module-error

标签

javascript

typescript

jestjs