[ng-dev] Feature request: AsyncTestingController

[ersimont]

Idea: Make a new AsyncTestingController to mimic Angular's HttpTestingController, to enable a consistent DX between testing both kinds of APIs.

The API may end up being used something like:

const clipboardController = new AsyncTestingController(navigator.clipboard, ['readText', 'writeText'], ctx);

clipboardController.expectNone('readText');

navigator.clipboard.readText().then((text) => console.log(text));

const calls = clipboardController.match('readText');
// -or-
const calls = clipboardController.match((call: CallInfo<Navigator['readText']>) => true);

const testCall = clipboardController.expectOne('readText');
// -or-
const testCall = clipboardController.expectOne((call: CallInfo<Navigator['readText']>) => {
  // return boolean
});

console.log(testCall.call.args); // `.call` is the jasmine CallInfo object
testCall.flush('resolve with this, with type safety');
testCall.error('a rejection reason of type any');

clipboardController.verify();

• Should calling flush() or error() after one of them was already called cause an error? (See what HttpTestingController does)?
• It would be nice for it to optionally interop with an AngularContext to trigger change detection on flush() and error(). (But first verify that zone.js does that in real life.)
• Use jasmine spies so that it automatically cleans up after itself after each test