getInstances type is incorrect: returns a Promise when callback is unspecified

[lukasschwab]

Environment details

• OS: macOS 10.14
• Node.js version: v12.12.0
• npm version: 6.11.3
• @google-cloud/bigtable version: 2.2.1

Steps to reproduce

I have code that calls getInstances without defining a callback:

const [instances] = await bigtable.getInstances();

getInstances behaves according to its docstring:

If the callback is omitted, we'll return a Promise.

...but this behavior is not reflected in its generated type, which has return type void and no overloads:

getInstances(gaxOptions?: any, callback?: any): void;

This mismatch causes eslint to complain because void is a non-Promise.

Proposal

Declare an overload type:

getInstances(gaxOptions?: any, callback: any): void;
getInstances(gaxOptions?: any): Promise<Instance[]>;

Thanks!

[jkwlui]

We need to annotate this client like the way we do with other TypeScript libraries.

[lukasschwab]

@jkwlui can you link one of the annotated libraries/documentation for the annotation style? I'd be happy to give it a shot this weekend.

[callmehiphop]

@JustinBeckwith @jkwlui looks like we're missing types across the board for the entire client. Is this something that is being prioritize? There isn't an open issue or anything, but I'd be happy to try and take this if some one isn't already.

[bcoe]

@callmehiphop could we leverage @alexander-fenster's work to auto-generate types with the new micro-generator?

[callmehiphop]

@bcoe it would help in some aspects like having request/response types mapped out for us.

[xiaowei-routific]

We are currently adopting bigtable right now and having the same problem. We have a thin layer of wrapper of our own right now and really hope that this could be prioritized

[jgehrcke]

Can we do the same for createInstance and other entry points?