Entity service waitForEntity returns too early

[richard-cox]

• To reproduce
  • Edit src/frontend/app/shared/components/add-service-instance/create-service-instance-helper.service.ts
  • comment out filter(o => !!o && !!o.entity && !!o.entity.entity && !!o.entity.entity.service_plans),
  • add filter(o => !!o && !!o.entity)
  • start afresh on the service instance wall
  • click 'edit' action on a service
  • exception thrown in console due to missing inline entity
• What's going on under the hood
  • cf service is fetched without service_plans in service wall
  • in edit stepper entity service created for cf service entity, this states service_plans is required
  • waitForEntity is subbed to
  • cf service entity is validated, service_plans identified
  • validation process marks cf service is updating
  • service_plans are fetched and saved in store (and in line)
  • validation process marks cf service as not updating
  • However... before the service_plans response is stored in the store a stale service request info state is pumped up the observable chain, this doesn't have the updating flag and thus passes the waitForEntity filter
• see branch rc-wait-for-bug

[richard-cox]

Bumped into this again during #3326 (after fix that issue the code requires tweaking to reproduce this issue)
Basically as ValidateEntities process is done via actions/effects now instead of synchronous functions as before we let an entity through which does not have the required fields

1. Entity service is created and getEntityObservable is called
2. Finds an entity in store (with a missing relation)
3. Kicks off asyncronously validation process (which will discover missing property, mark entity as updating, fetch missing property, mark entity as not updating)
4. Async actions of validation do not occur quick enough for waitForEntity, which see's an entity that's not updating and returns an invalid entity

this.entityObs$ = this.getEntityObservable(
      entityMonitor,
      this.actionDispatch,
    ).pipe(
      publishReplay(1),
      refCount(),
      tap((entityInfo: EntityInfo) => {
        if (!entityInfo || entityInfo.entity) {
          if ((!validateRelations || validated || isEntityBlocked(entityInfo.entityRequestInfo))) {
            return;
          }
          validated = true;
          store.dispatch(new ValidateEntitiesStart(
            action as ICFAction,
            [entityInfo.entity.metadata.guid],
            false
          ));
        }
      })
    );

    this.waitForEntity$ = this.entityObs$.pipe(
      filter((ent) => {
        const { entityRequestInfo, entity } = ent;
        return this.isEntityAvailable(entity, entityRequestInfo);
      }),
      publishReplay(1),
      refCount()
    );