feat: allow use of javascript in config file

[elevatebart]

Closes https://cypress-io.atlassian.net/browse/UNIFY-346

Preamble

As discussed with @jennifer-shehane on Sep 9th 2021, this PR is the first of a series of PRs to get to the cypress.config.ts new syntax. This is a follow-up to #17000.

Here is the list of discreet changes that will be merged as gradually as possible into develop:

First, these will not change end-user experience

• Allow cypress.config.js with the exact same data schema as a custom config file
• Allow cypress.config.js as a default config file
• Allow the use of TypeScript for configuring cypress cypress.config.ts
• Add the defineConfig() function to facilitate configuration in a JavaScript file
• Add the setupNodeEvents() config to configure plugins in the cypress.config.js file
  • Error when using a pluginsFile with cypress.config.js
• Add the component.devServer() + component.devServerOptions to streamline configuration of component testing.
• Make warnings visible in component testing when there is any.

Then changing the defaults and adding warning

• Warn when still using cypress.json
  • in the terminal
  • in the desktop-gui
  • in the component testing interface
• Change initial default scaffolding from using cypress.json and plugins/index.js to using cypress.config.js

User facing changelog

• One can now use JavaScript to define the content of what was before in the cypress.json file. Use the option --config-file my.config.for.cypress.js to specify where your file is.

Additional details

• Chokidar update was necessary for watching cypress.config.js properly

To test

Create a project with a js file as the config file

yarn create vite test-project
cd text-project
yarn create cypress-tests
mv cypress.json cypress.config.custom.js

Then open cypress.config.custom.js and write module.exports = { viewportWidth:300 } in it.

yarn cypress open --config-file cypress.config.custom.js

PR Tasks

• Have tests been added/updated?

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[cypress]

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Test summary

4189 • 0 • 50 • 2 • 1

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Run details

Project	cypress
Status	Passed
Commit	9c6b625
Started	Sep 22, 2021 6:27 PM
Ended	Sep 22, 2021 6:37 PM
Duration	09:53 💡
OS	Linux Debian - 10.9
Browser	Chrome beta 94

View run in Cypress Dashboard ➡️

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Flakiness

	cypress/integration/e2e/redirects_spec.js		1
1	redirection > meta > binds to the new page after a timeout

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[jennifer-shehane]

Updating from develop since we fixed the intercept flaky tests. Hopefully this should help determine flake from failures.

[JessicaSachs]

This looks good to me. I thoroughly tested the e2e runner.

[JessicaSachs]

This looks good @jennifer-shehane. Ready to go as soon as you give your 👍.

[cypress-bot]

Released in 8.5.0.

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