Cypress: Preprocessor opens another Cypress instance when bundling

[bahmutov]

This issue happens in Cypress v5.0.0 and does not occur in v4.12.1

If you try to run Cypress tests in https://github.com/eggheadio/egghead-next then a curious thing happens: it pops a new Cypress instance while trying to bundle.

Recording: https://jumpshare.com/v/v5mfJi5QlSbsd7IpBFAb

[ctorresDespegar]

I have the same problem in cypress v5.0.2. It always opens multiple windows but never it run the tests.

[bahmutov]

Narrowed it down to these dependencies

  "dependencies": {
    "next": "^9.5.3"
  },
  "devDependencies": {
    "cypress": "5.2.0",
    "jest": "^26.4.2"
  }

and .babelrc file

{
  "presets": ["next/babel"],
  "plugins": ["istanbul"]
}

$ npm ls babel-plugin-istanbul
[email protected] /Users/gleb/git/egghead-next
└─┬ [email protected]
  └─┬ @jest/[email protected]
    ├─┬ @jest/[email protected]
    │ └── [email protected] 
    └─┬ [email protected]
      └─┬ [email protected]
        └── [email protected]  deduped

Top level dependencies

$ npm ls --depth 0
[email protected] /Users/gleb/git/egghead-next
├── [email protected]
├── [email protected]
├── [email protected]
├── UNMET PEER DEPENDENCY react@^16.6.0
└── UNMET PEER DEPENDENCY react-dom@^16.6.0

Behavior: when you click on the spec.js it opens second global instance of Cypress

[bahmutov]

Reproducible example in https://github.com/cypress-io/cypress-test-tiny/tree/open-global

• clone repo
• npm install
• npx cypress open
• click on the spec

See the second instance of Cypress open!

Relevant portion of the debug log

 cypress:server:cypress starting cypress with argv [ '/Users/gleb/Library/Caches/Cypress/5.2.0/Cypress.app/Contents/MacOS/Cypress', '/Users/gleb/git/cypress-test-tiny/node_modules/babel-plugin-istanbul/lib/load-nyc-config-sync.js', '/Users/gleb/git/cypress-test-tiny' ] +0ms
  cypress:server:args argv array: [ '/Users/gleb/Library/Caches/Cypress/5.2.0/Cypress.app/Contents/MacOS/Cypress', '/Users/gleb/git/cypress-test-tiny/node_modules/babel-plugin-istanbul/lib/load-nyc-config-sync.js', '/Users/gleb/git/cypress-test-tiny' ] +0ms
  cypress:server:args argv parsed: { _: [ '/Users/gleb/Library/Caches/Cypress/5.2.0/Cypress.app/Contents/MacOS/Cypress', '/Users/gleb/git/cypress-test-tiny/node_modules/babel-plugin-istanbul/lib/load-nyc-config-sync.js', '/Users/gleb/git/cypress-test-tiny' ], invokedFromCli: false, cwd: '/Users/gleb/Library/Caches/Cypress/5.2.0/Cypress.app/Contents/Resources/app/packages/server' }

[bahmutov]

Traced it inside babel-plugin-istanbul to the function that loads the config like this

function loadNycConfig(cwd, opts) {
  ...
  const result = JSON.parse((0, _child_process.execFileSync)(process.execPath, args));
  ...
  return config;
}

Which in our case starts Cypress pointing at the args! For example if we print the args

console.log('about to execute')
console.log(process.execPath, args.join(' '))

we get

about to execute
/Users/gleb/Library/Caches/Cypress/5.2.0/Cypress.app/Contents/MacOS/Cypress 
  /Users/gleb/git/cypress-test-tiny/node_modules/babel-plugin-istanbul/lib/load-nyc-config-sync.js 
  /Users/gleb/git/cypress-test-tiny

Because it thinks it is executing inside Node, thus uses exec process to load other scripts as child processes. Should we separate every bundler better into a child process to solve this - because this one executes a child process _inside a require_.

[bahmutov]

Note: using system Node is NOT a workaround. The setting below still opens Cypress while loading babel options

{
  "nodeVersion": "system"
}

[johnlindquist]

Is there any movement on this? Kinda waiting on it so we can switch back to v5...

[chrisbreiding]

@johnlindquist I'm planning to look into this sometime in the next few days. Sorry for the inconvenience!

[nhynes]

@chrisbreiding thanks for looking into this. I'm getting the same issue using TS and Parcel without any explicit babel-plugin-istanbul. I'm also using route2, so I can't go back to 4.x.

[chrisbreiding]

@bahmutov: Should we separate every bundler better into a child process to solve this - because this one executes a child process inside a require.

That's exactly what we need to do. We do this for user-registered preprocessors, but when the user has not registered a preprocessor, we register our own default preprocessor _in the main Cypress process_. I'm fixing this in #8826 by now registering the default preprocessor in the plugins child process as well.

[bahmutov]

👏 👏 👏

Sent from my iPhone

On Oct 13, 2020, at 12:02, Chris Breiding [e-mail] wrote:


@bahmutov: Should we separate every bundler better into a child process to solve this - because this one executes a child process inside a require.

That's exactly what we need to do. We do this for user-registered preprocessors, but when the user has not registered a preprocessor, we register our own default preprocessor in the main Cypress process. I'm fixing this in #8826 by now registering the default preprocessor in the plugins child process as well.

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[cypress-bot[bot]]

The code for this is done in cypress-io/cypress#8826, but has yet to be released.
We'll update this issue and reference the changelog when it's released.

[cypress-bot[bot]]

Released in 5.4.0.

This comment thread has been locked. If you are still experiencing this issue after upgrading to
Cypress v5.4.0, please open a new issue.