Fix fs.promises.watch context stuff

Added tests to prevent regression

Author: james-pre

src/emulation/promises.ts

@@ -951,9 +951,10 @@ export function watch(
 	options?: fs.WatchOptions | string
 ): AsyncIterable<promises.FileChangeInfo<string>> | AsyncIterable<promises.FileChangeInfo<Buffer>>;
 export function watch<T extends string | Buffer>(this: V_Context, filename: fs.PathLike, options: fs.WatchOptions | string = {}): AsyncIterable<promises.FileChangeInfo<T>> {
+	const context = this;
 	return {
 		[Symbol.asyncIterator](): AsyncIterator<promises.FileChangeInfo<T>> {
-			const watcher = new FSWatcher<T>(this, filename.toString(), typeof options !== 'string' ? options : { encoding: options as BufferEncoding | 'buffer' });
+			const watcher = new FSWatcher<T>(context, filename.toString(), typeof options !== 'string' ? options : { encoding: options as BufferEncoding | 'buffer' });
 
 			// A queue to hold change events, since we need to resolve them in the async iterator
 			const eventQueue: ((value: IteratorResult<promises.FileChangeInfo<T>>) => void)[] = [];

tests/common/context.test.ts

@@ -16,4 +16,21 @@ suite('Context', () => {
 	test('break-out fails', () => {
 		assert.deepEqual(c_fs.readdirSync('/../../'), ['example.txt']);
 	});
+
+	test('watch should consider context', async () => {
+		let lastFile: string,
+			events = 0;
+		const watcher = c_fs.promises.watch('/', { recursive: true });
+
+		(async () => {
+			for await (const event of watcher) {
+				lastFile = event.filename!;
+				if (++events == 2) return;
+			}
+		})();
+		await c_fs.promises.writeFile('/xpto.txt', 'in real root');
+		assert.strictEqual(lastFile!, 'xpto.txt');
+		await c_fs.promises.unlink('/xpto.txt');
+		assert.strictEqual(lastFile, 'xpto.txt');
+	});
 });