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import { DetachedPromise } from '../../lib/detached-promise'
import { trackStreamConsumed } from './web-on-close'
describe('trackStreamConsumed', () => {
it('calls onEnd when the stream finishes', async () => {
const endPromise = new DetachedPromise<void>()
const onEnd = jest.fn(endPromise.resolve)
const { stream: inputStream, controller } =
readableStreamWithController<string>()
const trackedStream = trackStreamConsumed(inputStream, onEnd)
const reader = trackedStream.getReader()
controller.enqueue('one')
controller.enqueue('two')
await reader.read()
await reader.read()
expect(onEnd).not.toHaveBeenCalled()
controller.close()
await expect(reader.read()).resolves.toEqual({
done: true,
value: undefined,
})
await endPromise.promise
expect(onEnd).toHaveBeenCalledTimes(1)
})
it('calls onEnd when the stream errors', async () => {
const endPromise = new DetachedPromise<void>()
const onEnd = jest.fn(endPromise.resolve)
const { stream: inputStream, controller } =
readableStreamWithController<string>()
const trackedStream = trackStreamConsumed(inputStream, onEnd)
const reader = trackedStream.getReader()
controller.enqueue('one')
controller.enqueue('two')
await reader.read()
await reader.read()
expect(onEnd).not.toHaveBeenCalled()
const error = new Error('kaboom')
controller.error(error)
// if the underlying stream errors, we should error as well
await expect(reader.read()).rejects.toThrow(error)
await endPromise.promise
expect(onEnd).toHaveBeenCalledTimes(1)
})
it('calls onEnd when the stream is cancelled', async () => {
const endPromise = new DetachedPromise<void>()
const onEnd = jest.fn(endPromise.resolve)
const cancelledPromise = new DetachedPromise<unknown>()
const onCancel = jest.fn(cancelledPromise.resolve)
const { stream: inputStream, controller } =
readableStreamWithController<string>(onCancel)
const trackedStream = trackStreamConsumed(inputStream, onEnd)
const reader = trackedStream.getReader()
controller.enqueue('one')
controller.enqueue('two')
await reader.read()
await reader.read()
expect(onEnd).not.toHaveBeenCalled()
const cancellationReason = new Error('cancelled')
await reader.cancel(cancellationReason)
// from a reader's perspective, a cancelled stream behaves like it's done
// (which is a bit weird honestly?)
await expect(reader.read()).resolves.toEqual({
done: true,
value: undefined,
})
await endPromise.promise
expect(onEnd).toHaveBeenCalledTimes(1)
// the cancellation should propagate to back to the underlying stream
await cancelledPromise.promise
expect(onCancel).toHaveBeenCalledWith(cancellationReason)
})
})
function readableStreamWithController<TChunk>(
onCancel?: (reason: unknown) => void
) {
let controller: ReadableStreamDefaultController<TChunk> = undefined!
const stream = new ReadableStream<TChunk>({
start(_controller) {
controller = _controller
},
cancel(reason) {
onCancel?.(reason)
},
})
return { controller, stream }
}
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