voice - fix issues around stopping transcription (microsoft#191774)

Author: bpasero

src/vs/base/common/event.ts

@@ -557,6 +557,24 @@ export namespace Event {
 		return new Promise(resolve => once(event)(resolve));
 	}
 
+	/**
+	 * Creates an event out of a promise that fires once when the promise is
+	 * resolved with the result of the promise or `undefined`.
+	 */
+	export function fromPromise<T>(promise: Promise<T>): Event<T | undefined> {
+		const result = new Emitter<T | undefined>();
+
+		promise.then(res => {
+			result.fire(res);
+		}, () => {
+			result.fire(undefined);
+		}).finally(() => {
+			result.dispose();
+		});
+
+		return result.event;
+	}
+
 	/**
 	 * Adds a listener to an event and calls the listener immediately with undefined as the event object.
 	 *

src/vs/base/test/common/event.test.ts

@@ -4,7 +4,7 @@
  *--------------------------------------------------------------------------------------------*/
 import * as assert from 'assert';
 import { stub } from 'sinon';
-import { timeout } from 'vs/base/common/async';
+import { DeferredPromise, timeout } from 'vs/base/common/async';
 import { CancellationToken } from 'vs/base/common/cancellation';
 import { errorHandler, setUnexpectedErrorHandler } from 'vs/base/common/errors';
 import { AsyncEmitter, DebounceEmitter, DynamicListEventMultiplexer, Emitter, Event, EventBufferer, EventMultiplexer, IWaitUntil, MicrotaskEmitter, PauseableEmitter, Relay, createEventDeliveryQueue } from 'vs/base/common/event';
@@ -1158,6 +1158,48 @@ suite('Event utils', () => {
 		listener.dispose(); // should not crash
 	});
 
+	suite('fromPromise', () => {
+
+		test('not yet resolved', async function () {
+			return new Promise(resolve => {
+				let promise = new DeferredPromise<number>();
+
+				Event.fromPromise(promise.p)(e => {
+					assert.strictEqual(e, 1);
+
+					promise = new DeferredPromise();
+
+					Event.fromPromise(promise.p)(() => {
+						resolve();
+					});
+
+					promise.error(undefined);
+				});
+
+				promise.complete(1);
+			});
+		});
+
+		test('already resolved', async function () {
+			return new Promise(resolve => {
+				let promise = new DeferredPromise<number>();
+				promise.complete(1);
+
+				Event.fromPromise(promise.p)(e => {
+					assert.strictEqual(e, 1);
+
+					promise = new DeferredPromise();
+					promise.error(undefined);
+
+					Event.fromPromise(promise.p)(() => {
+						resolve();
+					});
+				});
+
+			});
+		});
+	});
+
 	suite('Relay', () => {
 		test('should input work', () => {
 			const e1 = new Emitter<number>();