[Bug] create-react-app/react-scripts test fails to get correct pnpapi

• I’d be willing to implement a fix

Describe the bug

When using a simple Jest test that does a require(‘pnpapi’), it gets this error: The whole PnP file got strict-mode-ified, which is known to break (Emscripten libraries aren’t strict mode). This usually happens when the file goes through Babel.

To Reproduce

1. yarn dlx create-react-app my-app
2. cd my-app/src
3. Create this test case, in pnpapi.test.js

describe('Pipapi test', () => {
  test('pnpali', async () => {
    const pnpapi = require('pnpapi');
    pnpapi.findPackageLocator();
  });
});

1. cd …
2. yarn react-scripts test src/pnpapi.test.js
3. You will see output similar to this:

 FAIL  src/pnpapi.test.js
  Pipapi test
    ✕ pnpali (290ms)

  ● Pipapi test › pnpali

    The whole PnP file got strict-mode-ified, which is known to break (Emscripten libraries aren't strict mode). This usually happens when the file goes through Babel.

       5 |   Object.freeze({}).detectStrictMode = true;
       6 | } catch (error) {
    >  7 |   throw new Error(`The whole PnP file got strict-mode-ified, which is known to break (Emscripten libraries aren't strict mode). This usually happens when the file goes through Babel.`);
         |         ^
       8 | }
       9 | 
      10 | var __non_webpack_module__ = module;

      at Object.<anonymous> (.pnp.js:7:9)
      at Object.<anonymous> (src/pnpapi.test.js:4:20)

Test Suites: 1 failed, 1 total
Tests:       1 failed, 1 total
Snapshots:   0 total
Time:        2.532s, estimated 3s

Environment if relevant (please complete the following information):

• OS: [OSX 10.15.6]
• Node version [12.16.2]
• Yarn version [2.3.3]

[francisu]

Perfect, that fixed the problem. Thanks for your time, patience, and working on yarn 2. I’m really liking it.

[merceyz]

react-scripts overwrites it with their own config https://github.com/facebook/create-react-app/blob/d07b7d025f5933710fcb01718617dbdf4bc54c33/packages/react-scripts/scripts/utils/createJestConfig.js#L52-L55 you can patch it to work around that https://yarnpkg.com/features/protocols/#patch