Support @typescript-eslint/no-unused-vars rule

[karlhorky]

User facing changelog

This disables the ESLint @typescript-eslint/no-unused-vars rule (the typed counterpart to ESLint's built-in no-unused-vars)

Additional details

The files scaffolded by Cypress create an error out of the box for those users who are using @typescript-eslint/no-unused-vars instead of no-unused-vars

This rule is also possible (and desirable) to use with JS files as well - it offers additional type information even in JS files so that the rule catches more problems.

How has the user experience changed?

Before: Error out of the box

After: No error

Original PR: cypress-io/cypress#17432

cc @flotwig

[CLAassistant]

All committers have signed the CLA.

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[cypress]

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Test summary

5 • 0 • 0 • 0

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Run details

Project	cypress-example-kitchensink
Status	Passed
Commit	7913c0a
Started	Jul 22, 2021 9:59 PM
Ended	Jul 22, 2021 10:02 PM
Duration	03:37 💡
OS	Linux Ubuntu - 16.04
Browser	Custom chromium 90

View run in Cypress Dashboard ➡️

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[MikeMcC399]

@emilyrohrbough

"This branch has conflicts that must be resolved".

This PR changes a file which no longer exists under Cypress 10+

Did you approve it by accident? Can we check that the issue it was addressing still exists?

[MikeMcC399]

cypress/plugins/index.js is created by default after starting Cypress 9.7.0 with

// eslint-disable-next-line no-unused-vars
module.exports = (on, config) => {
  // `on` is used to hook into various events Cypress emits
  // `config` is the resolved Cypress config
}

The file remains after updating to Cypress 12.9.0 and then running the migration wizard.

After a clean installation of Cypress 12.9.0, opening this version and running E2E scaffolding, no file cypress/plugins/index.js is created. There is no other file with the above problematic code snippet.

[MikeMcC399]

The issue targeted by this PR is obsolete and the PR can be closed. There is nothing to fix anymore.

Modifications to examples in this repo (cypress-io/cypress-example-kitchensink) only flow into future versions of Cypress. They do not affect released versions or existing installations.

The issue only affects installations of Cypress Legacy configuration: Folders/files which were originally installed using Cypress 9 and lower.

Installations using Cypress current Configuration: Folders/files which were originally installed using Cypress 10+ are not affected. There is no file cypress/plugins/index.js created.

[MikeMcC399]

This PR should be closed because it is obsolete, but also because it would not have worked even if it had been dealt with in a timely manner.

Perhaps @karlhorky or one of the Cypress.io team could close it?

Rebasing

Attempting to rebase the branch https://github.com/karlhorky/cypress-example-kitchensink/tree/patch-2 on the master branch results in a conflict:

$ git rebase master pr/502
CONFLICT (modify/delete): cypress/plugins/index.js deleted in HEAD and modified in 7913c0a (Support @typescript-eslint/no-unused-vars rule).  Version 7913c0a (Support @typescript-eslint/no-unused-vars rule) of cypress/plugins/index.js left in tree.
error: could not apply 7913c0a... Support @typescript-eslint/no-unused-vars rule
hint: Resolve all conflicts manually, mark them as resolved with
hint: "git add/rm <conflicted_files>", then run "git rebase --continue".
hint: You can instead skip this commit: run "git rebase --skip".
hint: To abort and get back to the state before "git rebase", run "git rebase --abort".
Could not apply 7913c0a... Support @typescript-eslint/no-unused-vars rule

Since there is no other change in the PR apart from a modification to the deleted file cypress/plugins/index.js, after resolving the conflict, there is nothing left in the PR.

Effectiveness

It seems also that there was a misconception that changing cypress/plugins/index.js in this repository would affect the file delivered by installing and running a legacy Cypress version (9 or earlier). In fact although this file was packaged up and included in the npm module cypress-example-kitchensink, the Cypress build process described in Updating the example app using yarn workspace @packages/example build did not copy this file. See

https://github.com/cypress-io/cypress/blob/d681fd929bfeb4ca297d42ad77fc3d0e33dae793/packages/example/bin/convert.js#L44-L50

   glob('./cypress/integration/**/*.js', { realpath: true }, (err, specFiles) => {
    if (err) throw err

    htmlFiles.concat(specFiles).forEach(function (file) {
      return replaceStringsIn(file)
    })
  })

So even if Cypress were still using the layout which is now legacy, the PR would not have had the desired effect.

[karlhorky]

Yeah I'm thinking also that this PR is no longer needed.

If I see this happening in the latest versions, I'll open a new PR.

[MikeMcC399]

@karlhorky

Thanks for closing! I'm going through some of the eslint aspects at the moment, so please flag any issues if you find any new ones.