Testing NGXS states with sub states feeds wrong state into action handler - ngxs

Question

Setup:
I have a parent state defined as
#State<ParentStateModel>({
name: 'grid',
defaults: {
parentData: 'some data'
},
children: [LoadingState]
})
export class ParentState {
#Action(Action1)
action1(ctx: stateContext<ParentStateModel>, action: Action1) {
// In production this state will be ParentStateModel as expected
// but in unit test, it will be of type LoadingState
const state = ctx.getState();
}
}
And a child state defined as
#State<LoadingStateModel>({
name: 'gridLoading',
defaults: {
loading: false
}
})
export class LoadingState{
#Action(Action1)
action1(ctx: stateContext<LoadingStateModel>, action: Action1) {
ctx.setState({loading: true});
}
}
Notice that both states respond to Action1.
When running this in production, it works as it should. The loading state takes care of the LoadingStateModel and the ParentState takes care of the ParentStateModel.
But when unit testing the code, the action handler in ParentState is fed the LoadingStateModel instead of the ParentStateModel (see comment in code).
My unit test is setup as follows
TestBed.configureTestingModule({
imports: [NgxsModule.forRoot([CashflowState, LoadingState])]
});
If I do not include LoadingState in the imports array, NGXS fails with Child state not found: function LoadingState()
Am I doing something wrong, or is it a bug in NGXS?