Rule await-promise: make Promise implementation configurable

[darxriggs]

Feature Request

• TSLint version: 5.1.0
• TypeScript version: 2.3.2
• Running TSLint via: CLI

TypeScript code being linted

import * as Bluebird from 'bluebird';

function functionReturningThenable(): Bluebird.Thenable<string> {
    return Bluebird.resolve('some data');
}

async function main(): Promise<void> {
    const data = await functionReturningThenable();
    console.log(data);
}

with tslint.json configuration:

{
  "rules": {
    "await-promise": true
  }
}

Actual behavior

(await-promise) src/test.ts[8, 18]: 'await' of non-Promise.

Expected behavior

No error should be reported.

There are multiple Promise implementations and interfaces out there (JQueryPromise, Q.Promise, Thenable, etc.). Also see Promises/A+, Therefore the rule should be configurable like no-floating-promises already is.

[darxriggs]

I'd like to create PR for this but I've seen #2631 ("no-floating-promises: rewrite as walker function").

So the question is if this rule should use applyWithWalker or applyWithFunction and why?

[ajafff]

@darxriggs we want to move away from RuleWalker and therefore ProgramAwareRuleWalker and eventually deprecate them. await-promise has not been refactored to use either AbstractWalker or applyWithFunction. #2631 would be a good start.

Which one you choose is up to you. For simple rules it's preferred to use a function. When you find yourself in the need to add several closures to the walker function, you should consider using AbstractWalker to avoid the repeated closure allocation.
For more information about the concepts, there is some documentation at https://palantir.github.io/tslint/develop/custom-rules/walker-design.html