Function chunk

packages/ai/tests/stream-processor.test.ts:25–33

Create a typed StreamChunk by event type. Narrows the return to the * matching variant via `Extract`.

(
  type: T,
  fields?: Record<string, unknown>,
)

/** Create a typed StreamChunk by event type. Narrows the return to the
 *  matching variant via `Extract`. */
function chunk<T extends StreamChunk['type']>(
  type: T,
  fields?: Record<string, unknown>,
): Extract<StreamChunk, { type: T }> {
  return { type, timestamp: Date.now(), ...fields } as Extract<
    StreamChunk,
    { type: T }
  >
}

/** Create an async iterable from a list of chunks. */
async function* streamOf(