feat(utilities): add iterableToArray helper

packages/utilities/src/streams_utilities.ts

@@ -26,3 +26,35 @@ export async function readStreamToString(stream: Readable | PassThrough, encodin
     const buffer = await concatStreamToBuffer(stream);
     return buffer.toString(encoding);
 }
+
+function isAsyncIterable(value: unknown): value is AsyncIterable<unknown> {
+    return typeof value === 'object' && !!value && Symbol.asyncIterator in value;
+}
+
+async function asyncIterableToArray<T>(iterable: AsyncIterable<T>): Promise<T[]> {
+    const out: T[] = [];
+    for await (const item of iterable) {
+        out.push(item);
+    }
+
+    return out;
+}
+
+export function iterableToArray<T>(iterable: AsyncIterable<T>): Promise<T[]>;
+export function iterableToArray<T>(iterable: Iterable<T>): T[];
+
+/**
+ * Collect items from an iterable object or an async iterable into an array.
+ */
+export function iterableToArray<T>(iterable: AsyncIterable<T> | Iterable<T>) {
+    if (isAsyncIterable(iterable)) {
+        return asyncIterableToArray(iterable);
+    }
+
+    const out: T[] = [];
+    for (const item of iterable) {
+        out.push(item);
+    }
+
+    return out;
+}

test/streams_utilities.test.ts

@@ -0,0 +1,32 @@
+import { describe, expect, it } from 'vitest';
+
+import { iterableToArray } from '@apify/utilities';
+
+describe('iterableToArray', () => {
+    it('collects a synchronous iterable into an array', () => {
+        const result = iterableToArray(new Set([1, 2, 3]));
+
+        expect(result).toEqual([1, 2, 3]);
+    });
+
+    it('collects an async iterable into an array', async () => {
+        async function* gen() {
+            yield 'a';
+            yield 'b';
+            yield 'c';
+        }
+
+        const result = await iterableToArray(gen());
+
+        expect(result).toEqual(['a', 'b', 'c']);
+    });
+
+    it('propagates errors thrown by an async iterable', async () => {
+        async function* gen() {
+            yield 1;
+            throw new Error('boom');
+        }
+
+        await expect(iterableToArray(gen())).rejects.toThrow('boom');
+    });
+});