Xstate: Root transitions are not working properly

[hnordt]

Consider the following snippet:

const wordMachine = Machine({
  id: 'direction',
  initial: 'left',
  states: {
    left: {},
    right: {},
    center: {},
    justify: {}
  },
  on: {
    LEFT_CLICK: 'left',
    RIGHT_CLICK: 'right',
    CENTER_CLICK: 'center',
    JUSTIFY_CLICK: 'justify'
  }
});

If you copy and paste it in the Visualizer (https://statecharts.github.io/xstate-viz/) you'll see that you can transition to right by clicking on RIGHT_CLICK event.

It shouldn't happen. left means "travel to my sibling left state", direction has no siblings.

The expected result would be a warning: Target 'left' not found on 'direction' (or something like that).

[Andarist]

This is explicitly allowed here so I'm wondering if it's indeed a bug or just a documentation issue?

[hnordt]

I think it's a bug. left means a transition to a sibling, not to a child.

[hnordt]

If you add a parent foo state, the machine will be interpreted correctly:

const wordMachine = Machine({
  id: 'direction',
  initial: "foo",
  states: {
    foo: {
      initial: 'left',
      states: {
        left: {},
        right: {},
        center: {},
        justify: {}
      },
      on: {
        LEFT_CLICK: 'left',
        RIGHT_CLICK: 'right',
        CENTER_CLICK: 'center',
        JUSTIFY_CLICK: 'justify'
      }
    }
  }
});

It won't allow you to transition from left to right on RIGHT_CLICK because there's no right sibling.

[Andarist]

That would mean that in example those machines are wrongly configured:
https://github.com/davidkpiano/xstate/blob/0bd24b23f39a3971a2f879f918c032e5ff1c1285/test/actions.test.ts#L620
https://github.com/davidkpiano/xstate/blob/0bd24b23f39a3971a2f879f918c032e5ff1c1285/test/deep.test.ts#L5

[hnordt]

Yes, I believe they are wrong.

Waiting @davidkpiano thoughts on it.

For me transitions without a dot always mean a transition to a sibling state, and it should not resolve to a child state in any case.

If sibling transitions behave some way for the root state and then another way for children states, it's gonna be confusing.

[davidkpiano]

Yeah, they're wrong. Will fix.

[abhi18av]

Guys, does this issue still stand or perhaps it could be closed after the https://github.com/davidkpiano/xstate/pull/550 ?

[Andarist]

@abhi18av the issue still stands. It indeed got fixed in #550 but we couldn't merge it in, because it is a breaking change and we need to wait for the next major version for this to be fixed.

[abhi18av]

Cool 👍

I'm trying to understand the standing issues and PRs - apologies for notifications 😅

[Andarist]

No problem, thanks for looking into them!