How to setup jest ESM tests using lint-staged in a yarn monorepo

Question

I'm trying to run jest for ESM tests in yarn pnp monorepo,

// list-staged.config.js

    export default { 
      '**/*.js': [
       'eslint',
       'yarn run staged',
       'git add',
     ]
    }

staged script command in my root package.json,

    "script": {
      "staged": "yarn node --experimental-vm-modules $(yarn bin jest)",
      ...
    }

When I try to commit the code in file /example-project/pages/CheckoutPage.js, lint-staged should just run all the tests in the monorepo but I get this error (note that I have around 84 microservices in the monorepo),

No tests found, exiting with code 1 Run with --passWithNoTests to exit with code 0 In /Users/Saud/git/monorepo 5641 files checked across 84 projects. Run with --verbose for more details. Pattern: /Users/Saud/git/monorepo/example-project/pages/CheckoutPage.js - 0 matches

It's interesting that it's doing a match with the file changed while I haven't specify any options like --onlyChanged or --findRelatedTests in the command.

Root level jest.config.js:

    import collectCoverageFrom from './jest.collectCoverageFrom.js'
    
    export default {
      collectCoverageFrom,
      coverageReporters: ['lcov'],
      modulePathIgnorePatterns: [
        '<rootDir>/example-project',
      ],
      projects: [
        '<rootDir>/example-project',
      ],
      testEnvironment: 'jsdom',
    }

example-project/jest.config.js:

    import { readFile } from 'fs/promises'
    import excludeCoverageFrom from '@monorepo/root/jest.excludeCoverageFrom.js'
    
    export default {
      collectCoverageFrom: [
        '<rootDir>/example-project/**/*.js',
        ...excludeCoverageFrom,
      ],
      displayName: 'example-project',
      rootDir: '../',
      roots: ['<rootDir>/example-project'],
      setupFilesAfterEnv: [
        // '<rootDir>/jest.window.setImmediate.js',
        '<rootDir>/jest.window.scrollTo.js',
        '<rootDir>/jest.window.TextEncoder.js',
        '@testing-library/jest-dom/extend-expect',
      ],
      testEnvironment: 'jsdom',
      moduleNameMapper: {
        '\\.(jpg|jpeg|png|svg|webp)$': '<rootDir>/__mocks__/mockImage.js',
      },
      testPathIgnorePatterns: [
        '/cdk.out/',
        '/assets-.*/',
        '/bundles-.*/',
        '/lambda-.*/',
      ],
      coverageThreshold: {
        global: {
          branches: 50,
          functions: 50,
          lines: 50,
          statements: 50,
        },
      },
      transformIgnorePatterns: ['node_modules/(?!uuid)'],
    }

When I run the script itself, the test works fine. For some reason lint-staged is unable to process the yarn command to run jest tests with ESM support. My requirement is to run relevant tests on commits via passing options such as "--findRelatedTests" but for now I'm just trying to make it work. Anyone had this problem?

Other insights, I tried using the flag --findRelatedTests, these are the following commit logs from sourcetree,

[STARTED] Preparing lint-staged...
[SUCCESS] Preparing lint-staged...
[STARTED] Running tasks for staged files...
[STARTED] lint-staged.config.js — 1 file
[STARTED] **/*.js — 1 file
[STARTED] eslint
[SUCCESS] eslint
[STARTED] yarn run staged
[SUCCESS] yarn run staged
[STARTED] git add
[SUCCESS] git add
[SUCCESS] **/*.js — 1 file
[SUCCESS] lint-staged.config.js — 1 file
[SUCCESS] Running tasks for staged files...
[STARTED] Applying modifications from tasks...
[SUCCESS] Applying modifications from tasks...
[STARTED] Cleaning up temporary files...
[SUCCESS] Cleaning up temporary files...
Completed successfully

So for some reason it didn't run any test. I should mention that test file does exists for CheckoutPage.js in /example-project/pages/tests/CheckoutPage.test.js.

Answer 1

So I was using lint-staged incorrectly. I was trying to run all the tests in the monorepo when one file changed. As @jonrsharpe made me realized I didn't understand lint-staged properly. It's a tool for checking files that are going to be committed, so it only makes to run those tests whose files have changed via passing the "--findRelatedTests"