Type conflict when filtering detected browsers

[bahmutov]

in packages/launcher/lib/detect.ts

I had to add @ts-ignore to get around TypeScript error - the uniqBy(props(['name', 'version'])) would not work because "version" property on the Browser type is optional.

We probably need to be explicit and cast ourselves inside props or somehow switch type from Browser to DetectedBrowser.

See

cypress/packages/launcher/lib/detect.ts

Line 87 in 967f267

// @ts-ignore

Below is my experiments compacting and filtering

  // const removeDuplicates = uniqBy(props(['name', 'version']))
  const removeDuplicates = uniqBy((browser: Browser) => props(['name', 'version'], browser))

  // for some reason the type system does not understand that after _.compact
  // the remaining list only contains valid Browser objects
  // and we can pick "name" and "version" fields from each object
  const toUniqueBrowsers = (browsers: (Browser | boolean)[]) => {
    const justBrowsers: Browser[] = reject(isFalse)(browsers)
    return removeDuplicates(justBrowsers)
  }

[flotwig]

Even with just name (a required property) there is still a warning. I'll look and see if there's any knowledge about this from Ramda.

[flotwig]

/** returns list of detected browsers */
function detectBrowsers(goalBrowsers?: Browser[]): Bluebird<FoundBrowser[]> {
  // we can detect same browser under different aliases
  // tell them apart by the name and the version property
  if (!goalBrowsers) {
    goalBrowsers = browsers
  }
  const removeDuplicates = uniqBy((browser: FoundBrowser) => props(['name', 'version'], browser))
  return Bluebird.mapSeries(goalBrowsers, checkBrowser)
    .then(flatten)
    .then((foundBrowsers) => compact(foundBrowsers) as unknown as FoundBrowser[])
    .then(removeDuplicates)
}

This coerces all the errors away but it feels dirty casting to unknown then casting to FoundBrowser[]... though that's the workaround the warning suggests

[bahmutov]

or you can make it explicit and instead of `props...` do your own explicit function ``` uniqBy(nameAndVersion, ...) const nameAndVersion = (browser: Browser) => ${browser.name }-${browser.version!} ``` I think this will get rid of the error

[flotwig]

Doesn't work, it seems like the root of the issue is that Typescript thinks that compact will return a two-dimensional array, so I changed compact to this:

const compactFalse = (browsers: any[]) => compact(browsers) as FoundBrowser[]

and the warnings go away. Gonna merge this in with #3225 if there's no objection