refactor(core): Simplify createDeferredPromise, and add tests (no-changelog) (#10811)

packages/workflow/src/DeferredPromise.ts

@@ -1,14 +1,17 @@
-// From: https://gist.github.com/compulim/8b49b0a744a3eeb2205e2b9506201e50
+type ResolveFn<T> = (result: T | PromiseLike<T>) => void;
+type RejectFn = (error: Error) => void;
+
 export interface IDeferredPromise<T> {
-	promise: () => Promise<T>;
-	reject: (error: Error) => void;
-	resolve: (result: T) => void;
+	promise: Promise<T>;
+	resolve: ResolveFn<T>;
+	reject: RejectFn;
 }
 
-export async function createDeferredPromise<T = void>(): Promise<IDeferredPromise<T>> {
-	return await new Promise<IDeferredPromise<T>>((resolveCreate) => {
-		const promise = new Promise<T>((resolve, reject) => {
-			resolveCreate({ promise: async () => await promise, resolve, reject });
-		});
+export function createDeferredPromise<T = void>(): IDeferredPromise<T> {
+	const deferred: Partial<IDeferredPromise<T>> = {};
+	deferred.promise = new Promise<T>((resolve, reject) => {
+		deferred.resolve = resolve;
+		deferred.reject = reject;
 	});
+	return deferred as IDeferredPromise<T>;
 }

packages/workflow/src/Interfaces.ts

@@ -728,7 +728,7 @@ export interface ICredentialTestFunctions {
 }
 
 interface BaseHelperFunctions {
-	createDeferredPromise: <T = void>() => Promise<IDeferredPromise<T>>;
+	createDeferredPromise: <T = void>() => IDeferredPromise<T>;
 }
 
 interface JsonHelperFunctions {

packages/workflow/test/DeferredPromise.test.ts

@@ -0,0 +1,22 @@
+import { createDeferredPromise } from '@/DeferredPromise';
+
+describe('DeferredPromise', () => {
+	it('should resolve the promise with the correct value', async () => {
+		let done = false;
+		const deferred = createDeferredPromise<string>();
+		void deferred.promise.finally(() => {
+			done = true;
+		});
+		expect(done).toBe(false);
+		deferred.resolve('test');
+		await expect(deferred.promise).resolves.toBe('test');
+		expect(done).toBe(true);
+	});
+
+	it('should reject the promise with the correct error', async () => {
+		const deferred = createDeferredPromise();
+		const error = new Error('test error');
+		deferred.reject(error);
+		await expect(deferred.promise).rejects.toThrow(error);
+	});
+});