Tests are using code from npm instead of code from pull request

[brunolemos]

Possibly a regression from 5fecfee.
Blocking #4837.

Is this a bug report?

Yes

Environment

System:
OS: macOS 10.14
CPU: x64 Intel(R) Core(TM) i5-6267U CPU @ 2.90GHz
Binaries:
Node: 8.11.4 - /usr/local/bin/node
Yarn: 1.10.1 - ~/.yarn/bin/yarn
npm: 6.4.1 - /usr/local/bin/npm
Browsers:
Chrome: 69.0.3497.100
Firefox: 59.0.2
Safari: 12.0
npmPackages:
@stiligita/react: 1.0.0-0
@types/react: 16.4.14
@types/react-dom: 16.0.8
react: 16.5.2
react-dom: 16.5.2
react-scripts: 2.0.5 (#4837)
npmGlobalPackages:
create-react-app: Not Found (#4837)

Steps to Reproduce

• Fork TypeScript support using Babel 7 #4837
• Run CI=false npx jest --config ./test/jest.config.js --testMatch '<rootDir>/**/typescript/*.test.js' (pass)
• Run CI=true npx jest --config ./test/jest.config.js --testMatch '<rootDir>/**/typescript/*.test.js' (fail)

Expected Behavior

Tests should pass because they are correct.
CRA should use the current code of each pull request, not a version from npm.

Actual Behavior

TypeScript tests fails because it tries to use the cra version from npm, which doesn't support typescript.

Reproducible Demo

#4837

Possibly related code

https://github.com/facebook/create-react-app/blob/f89385f7438f39750b762590ebd9729534e30190/test/fixtures/__shared__/util/setup.js#L18

https://github.com/facebook/create-react-app/blob/f89385f7438f39750b762590ebd9729534e30190/test/fixtures/__shared__/util/setup.js#L37-L42

[Timer]

The tests are supposed to be using code from "npm" because the PR is published before the test are ran:
https://github.com/facebook/create-react-app/blob/f89385f7438f39750b762590ebd9729534e30190/tasks/e2e-behavior.sh#L90-L100

I suspect our registry override might be wiped out, or similar.

[Timer]

https://travis-ci.org/facebook/create-react-app/jobs/441577719#L606-L709 this looks suspicious. Nothing but yarn.lock should be removed.

[brunolemos]

I made the wrong diagnostic about the problem because locally I ran jest directly so it didn't make this publish to the local npm.

I added a console.log to see the real test error on travis: https://travis-ci.org/facebook/create-react-app/jobs/441692012#L787-L797 (btw I wish it showed this by default):

 FAIL  fixtures/typescript/index.test.js (25.768s)
  ● Console
    console.error fixtures/typescript/index.test.js:7
      { Error: Command failed: yarnpkg test --env node --ci
      FAIL src/App.test.ts
        ● Test suite failed to run
      
          Cannot find module './App' from 'App.test.ts'
      
          > 1 | import App from './App';

It loaded App.test.ts so it's using the correct code from the PR.
But App.test.ts is not being able to import ./App which is weird.

[brunolemos]

Adding .disable-pnp fixed it 🤔🎉

[Timer]

Hmm, I'd like to figure out why this doesn't work with PnP (it should).