Cypress types need refactoring

[bahmutov]

Cypress v6.4.0

I have described how to get rid of the global Cypress objects like cy, Cypress, assertion methods, and Mocha's functions in the blog post https://glebbahmutov.com/blog/local-cypress/ While looking at the types I have noticed a few weird things:

• the cypress-global-vars.d.ts imports the EventEmitter types, thus including the type NodeEventEmitter, but that type is already used in cypress.d.ts without an explicit import

Thus, to work around these things I had to repeat a bunch of code from Cypress types, see https://github.com/bahmutov/local-cypress/blob/main/index.ts

Also just noticed that our on Action type does not return the object, thus this code is invalid but runs just fine

// @ts-check
/// <reference types="cypress" />
Cypress.on('test:before:run', () => {
  console.log('before running a test')
}).on('test:after:run', () => {
  console.log('after running a test')
})

So we should fix the Action interface to return this I think

Proposal

Rejigger the type imports a little bit. The end-user will not notice a difference, but the types will actually make more sense and will be easier to work with if one wants to avoid global type clashes.

Outside of the scope

• the top-level type is a union of cypress and EventEmitter - which is confusing to the user I believe. This is done in https://github.com/cypress-io/cypress/blob/develop/cli/types/cypress-global-vars.d.ts

We can merge the type in our code and have the cy be just of type cy, same for the top-level Cypress type

I have opened #15022 for this part

[cypress-bot]

The code for this is done in cypress-io/cypress#14992, but has yet to be released.
We'll update this issue and reference the changelog when it's released.

[cypress-bot]

Released in 6.5.0.

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