Multiple next with non async function about compose

[Runrioter]

No, koa-compose support sync calls. The problem here is next() return a Promise. We need return Promise or include it in async function (had been included in test case).

The following one is use promise-based sync function.

  it(`should throw if next() is called multiple times in non async function`, () => {
    const stack = [];

    stack.push((ctx, next) => {
      return next().then(() => {
        return next()
      });
    });

    return compose(stack)({}).then(() => {
      throw new Error('boom')
    }, (err) => {
      assert(/multiple times/.test(err.message))
    })
  });

[Runrioter]

await compose(stack)({});

Here, await compose(stack)({}) is wrong.

[xyluet]

Yes, so it should caught in try catch, but it didn't.

[Runrioter]

Try this await expect(compose(stack)({})).rejects.toThrowError('next() called multiple times'); ?

@xyluet

[xyluet]

it(`should throw if next() is called multiple times in non async function`, async () => {
    const stack = [];

    stack.push((ctx, next) => {
      next();
      next();
    });

    await expect(compose(stack)({})).rejects.toThrowError('next() called multiple times');
  });

I tried that before, it resolved to value, but still throw error in UnhandledPromiseRejectionWarning

expect(received).rejects.toThrowError()

    Expected received Promise to reject, instead it resolved to value
      undefined

[fl0w]

expect doesn't return a promise, so the last example wouldn't work. koa-compose doesn't support sync calls, thus your last next() occurs out of context and the throw isn't caught.

It's the same as doing

try {
  Promise.reject()
} catch {
  // nothing to catch, nothing thrown yet
}

[fl0w]

@Runrioter that's exactly what I ment (I maybe expressed it badly). If you're dealing with them as promises the request chain isn't synchronous, the execute on a new tick.