[LionCheckboxIndeterminate]

[nbamfordcirium]

Expected behavior

LionCheckboxIndeterminate should have the appropriate state (checked, unchecked, or indeterminate) based on the state of its child checkbox elements when it is first created.

Actual Behavior

The last child checkbox element state is never processed and hence the indeterminate checkbox state is incorrect in some cases.

Subsequently changing the state works as expected.

https://studio.webcomponents.dev/edit/lqw33LqYQlzL0LC3rwzI

Additional context

lion-checkbox-group 0.21.1

The problem seems to be in LionCheckboxIndeterminate on line 209:

_onRequestToAddFormElement() {
    this._setOwnCheckedState();
}

According to the comments for FormRegistrartMixin, _onRequestToAddFormElement is called before the element is added, so the current checkbox element being added will never be visible when _setOwnCheckedState is called.