Test: downloadAndUnzipVSCode could have a constant overload 'insiders'

[bpasero]

Refs: #76039

export declare function downloadAndUnzipVSCode(version?: string | 'insiders'): Promise<string>;

[bpasero]

Same for other places where this can be done, e.g. version in runTest options.

[octref]

Tried this but I wouldn't get any insiders IntelliSense. For what benefit should we do this?

[bpasero]

@mjbvz I would expect a string constant to show up in the intellisense?

@octref yeah if it does not show up as help to the user, it is of not much value.

[mjbvz]

@octref Can you please share the function declaration you are using?

[octref]

@mjbvz Simple repro:

function downloadVSCodeArchive(version: string | 'foo') {}

downloadVSCodeArchive('|') // do completion here

I'm on TS 3.5.2.

[mjbvz]

Thanks. TS will reduce the type to the common string type in cases like that for the intellisense details / parameter hints. I believe that is the expected behavior

[octref]

@mjbvz Found upstream issue: microsoft/TypeScript#29729

Apparently this works:

type StringLiteralUnion<T extends U, U = string> = T | (U & { });
type DownloadVersion = StringLiteralUnion<'insiders' | 'stable'>;

I'll add insiders and stable constants.