fix: support AsyncIterator for stream API

src/index.ts

@@ -42,6 +42,11 @@ function stream(source: Pattern | Pattern[], options?: Options): NodeJS.Readable
 
 	const works = getWorks(source, ProviderStream, options);
 
+	/**
+	 * The stream returned by the provider cannot work with an asynchronous iterator.
+	 * To support asynchronous iterators, regardless of the number of tasks, we always multiplex streams.
+	 * This affects performance (+25%). I don't see best solution right now.
+	 */
 	return utils.stream.merge(works);
 }
 

src/utils/stream.spec.ts

@@ -5,14 +5,6 @@ import * as util from './stream';
 
 describe('Utils → Stream', () => {
 	describe('.merge', () => {
-		it('should return source stream as is, when he is alone', () => {
-			const source = new stream.PassThrough();
-
-			const actual = util.merge([source]);
-
-			assert.strictEqual(actual, source);
-		});
-
 		it('should merge two streams into one stream', () => {
 			const first = new stream.PassThrough();
 			const second = new stream.PassThrough();

src/utils/stream.ts

@@ -1,14 +1,6 @@
 import merge2 = require('merge2');
 
 export function merge(streams: NodeJS.ReadableStream[]): NodeJS.ReadableStream {
-	/**
-	 * Multiplexing leads to the creation of a new stream.
-	 * If the source is one, then there is nothing to multiplex.
-	 */
-	if (streams.length === 1) {
-		return streams[0];
-	}
-
 	const mergedStream = merge2(streams);
 
 	streams.forEach((stream) => {