Remove support for Node 6

[jennifer-shehane]

• close Drop Node 4 & 6 support from CLI #4200

User facing changelog

• Node 6 reached its end of life on April 30, 2019. This Node version will no longer be supported. The minimum Node version supported by Cypress is Node 8.
• Upgraded bluebird from 3.5.0 to 3.7.1.
• Upgraded cachedir from 2.2.0 to 2.3.0.
• Upgraded chalk from 2.4.2 to 3.0.0.
• Upgraded commander from 2.20.0 to 4.0.1.
• Upgraded debug from 3.2.6 to 4.1.1.
• Upgraded execa from 0.10.0 to 3.3.0.
• Upgraded fs-extra from 5.0.0 to 8.1.0.
• Upgraded is-ci from 1.2.1 to 2.0.0.
• Upgraded is-installed-globally from 0.1.0 to 0.3.1.
• Upgraded log-symbols from 2.2.0 to 3.0.0.
• Upgraded supports-color from 6.1.0 to 7.1.0.
• Upgraded untildify from 3.0.3 to 4.0.0.

PR Tasks

• [NA] Have tests been added/updated?
• Has a PR for user-facing changes been opened in cypress-documentation? Is part of 4.0 docs Cypress 4.0 Docs cypress-documentation#1710
• [NA] Have API changes been updated in the type definitions?
• [NA] Have new configuration options been added to the cypress.schema.json?

[cypress-bot]

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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

3061 • 0 • 46 • 0

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Run details

Project	cypress
Status	Passed
Commit	feb83f4
Started	Nov 19, 2019 7:42 PM
Ended	Nov 19, 2019 7:46 PM
Duration	03:41 💡
OS	Linux Debian - 9.8
Browser	Chrome 73

View run in Cypress Dashboard ➡️

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[chrisbreiding]

LGTM 👍

[NMinhNguyen]

Not too familiar with the way the project is built, but should we also update the build step to not transpile everything and only enough for Node.js 8 to interpret it? E.g. this would allow const to be used and I believe async/await too. Doesn’t have to be in this PR btw, just a thought I had 🙂

[chrisbreiding]

That's a good thought. I don't think we transpile any JavaScript that gets run in Node, but for CoffeeScript and TypeScript, we may be able to change the transpilation target. Any thoughts, @gleb?

[bahmutov]

So, this is CLI package, and we transpile cli/lib code into cli/build using script scripts/start-build.js that includes

shell.exec('babel lib -d build/lib')
shell.exec('babel index.js -o build/index.js')

I think we do need to look at what it targets now - I don't think it will make a lot of difference though for CLI code since we don't use async/await in our CLI source code.

I will open two separate issues:

• check babel transpile settings for CLI (above)
• check target version for our own TypeScript transpiles in packages/*

but overall this PR seems good to go as is

[flotwig]

Released in 4.0.0.

[kuceb]

if you have node < 8.12.0 you'll get an error when trying to install via yarn since execa lists engines > 8.12.0

error execa@3.3.0: The engine "node" is incompatible with this module. Expected version "^8.12.0 || >=9.7.0". Got "8.9.3"

[jennifer-shehane]

execa began requiring 8.12.0 in their engines in 2.0.1 as a bug fix, not noting it as a breaking change, which is like lol

I've opened a new issue here: #6512