Function start

test/fetch.test.ts:1770–1773

(controller)

      const payload = `{"x":"${'A'.repeat(oversize - 10)}"}`;
      const stream = new ReadableStream<Uint8Array>({
        start(controller) {
          controller.enqueue(new TextEncoder().encode(payload));
          controller.close();
        },
      });
      const response = createMockResponse({
        status: 429,