Function start

packages/browser-utils/test/networkUtils.test.ts:219–222

(controller)

      it('works with ReadableStream', () => {
        const stream = new ReadableStream({
          start(controller) {
            controller.enqueue(new TextEncoder().encode('stream data'));
            controller.close();
          },
        });
        const request = new Request('http://example.com', {
          method: 'POST',