fix: correct bad propagation of exit signals

[flotwig]

• Closes Audit usage of on('exit') to propagate exits + fix buggy usages #7722

User facing changelog

• Fixed an issue where Cypress could exit successfully even with failing tests under certain conditions.

Additional details

• if Cypress was spawned in global mode and was killed via a signal, the parent process would exit with a 0 exit code due to Audit usage of on('exit') to propagate exits + fix buggy usages #7722
• also fixed an instance of this pattern in the server tests
• all other instances of exit signal handling are correct

How has the user experience changed?

PR Tasks

• Have tests been added/updated?
• Has the original issue been tagged with a release in ZenHub?
• [na] Has a PR for user-facing changes been opened in cypress-documentation?
• [na] Have API changes been updated in the type definitions?
• [na] Have new configuration options been added to the cypress.schema.json?

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[cypress]

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Test summary

7644 • 0 • 119 • 0

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Run details

Project	cypress
Status	Passed
Commit	da32a8f
Started	Jun 22, 2020 5:33 PM
Ended	Jun 22, 2020 5:40 PM
Duration	06:41 💡
OS	Linux Debian - 10.1
Browser	Multiple

View run in Cypress Dashboard ➡️

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[brian-mann]

This appears to only change when we fork the process based on the usage of NODE_OPTIONS which to me does not seem to reflect the reason this issue was opened (it mentions the use of global mode).

How would changing the util/node_options affect global mode?

[flotwig]

@brian-mann util/node_options relaunches the Electron app if it is launched without the correct NODE_OPTIONS. The CLI always launches the Electron app with the correct options, so in released versions of Cypress, Electron will only practically be relaunched via util/node_options if launched in global mode (since the user will presumably not pass the expected NODE_OPTIONS).

[flotwig]

Other situations where the binary is launched directly (scripts, our own e2e tests...) will also benefit from this fix, which is why the changelog mentions "certain conditions" and not "global mode" explicitly.

[brian-mann]

Since this is fixing a userland bug, it needs tests. you can unit test this specific function if you'd like if its too difficult to recreate its usage in the real world.

we have some existing test patterns for testing cp.spawn methods you could look for in the CLI, etc.