Detect and cleanly exit from renderer crashes

[flotwig]

• Closes Detect browser/renderer crashes  #6170

User facing changelog

• Cypress will now detect if your browser tab has crashed and will cleanly exit.

Additional details

• previously, Cypress would hang open until the CI job timed out
• methods used to tell if the browser tab has crashed:
  • if the user is not cy.visiting, and the socket disconnects, and there is not a new runner connection within 5 seconds, the browser tab crashed
  • if the user is cy.visiting, the socket disconnects, and it does not reconnect within 10 seconds (generous)
  • this makes the code a lot more complex, maybe the rules should just be "if the runner disconnects, and it does not reconnect within 10 seconds, the browser tab crashed" - don't try to be smart about it
    • apparently socket.io can and will disconnect and reconnect, so there should be a delay in either case
    • since 10 seconds is kinda a long delay, maybe these two cases should remain separate
• what do we do when an unexpected exit does occur?
  • browser is left open for debugging
  • in open mode: a warning is logged to stdio
  • in run mode: an error is thrown and tests end
• if the extension d/c's in run mode, force exit
• keep extension d/c error message the same

Most of the meat of the error has been moved to the docs. Docs PR: cypress-io/cypress-documentation#2413

User Experience Changes

• users will now see the BROWSER_CRASHED error message in stdout if the browser crashes in open mode
• users will see their tests exit early if the browser crashes, or if the extension disconnects, in run mode
• webextension disconnections now cause tests to end in run mode

PR Tasks

• Have tests been added/updated?
• Has the original issue been tagged with a release in ZenHub?
• Has a PR for user-facing changes been opened in cypress-documentation? Update error docs around renderer crashes cypress-documentation#2413

[cypress-bot]

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PR Review Checklist

If any of the following requirements can't be met, leave a comment in the review selecting 'Request changes', otherwise 'Approve'.

User Experience

• The feature/bugfix is self-documenting from within the product.
• The change provides the end user with a way to fix their problem (no dead ends).

Functionality

• The code works and performs its intended function with the correct logic.
• Performance has been factored in (for example, the code cleans up after itself to not cause memory leaks).
• The code guards against edge cases and invalid input and has tests to cover it.

Maintainability

• The code is readable (too many nested 'if's are a bad sign).
• Names used for variables, methods, etc, clearly describe their function.
• The code is easy to understood and there are relevant comments explaining.
• New algorithms are documented in the code with link(s) to external docs (flowcharts, w3c, chrome, firefox).
• There are comments containing link(s) to the addressed issue (in tests and code).

Quality

• The change does not reimplement code.
• There's not a module from the ecosystem that should be used instead.
• There is no redundant or duplicate code.
• There are no irrelevant comments left in the code.
• Tests are testing the code’s intended functionality in the best way possible.

Internal

• The original issue has been tagged with a release in ZenHub.

[cypress]

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Test summary

6954 • 0 • 97 • 0

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Run details

Project	cypress
Status	Passed
Commit	0e74adf
Started	Mar 16, 2020 3:23 PM
Ended	Mar 16, 2020 3:29 PM
Duration	06:08 💡
OS	Linux Debian - 10.1
Browser	Multiple

View run in Cypress Dashboard ➡️

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