Testing if a record and it’s relations have been destroyed - ember.js

Question

I've created an Ember service with a method to destroy a record and it's related data (defined by relationships in the model).
This is my delete-user.js service.
import Promise from 'rsvp';
import Service, { inject as service } from '#ember/service';
export default Service.extend({
store: service(),
deleteUserAndAssociatedData(userRecord) {
return userRecord.get('posts')
.then(postRecords => this._deletePosts(postRecords))
.then(() => userRecord.destroyRecord());
},
_deletePosts(postRecords) {
return Promise
.all(postRecords.invoke('destroyRecord'));
}
});
My question is how am I supposed to test this functionality? I would like to verify that the user and it's posts have been marked as destroyed.
This is what I have so far in delete-user-test.js:
import { moduleFor, test } from 'ember-qunit';
import { run } from '#ember/runloop';
import { A } from '#ember/array';
import EmberObject from '#ember/object';
moduleFor('service:delete-user', 'Integration | Service | delete-user', {
integration: true
});
let generateDummyUser = container => {
const store = container.lookup('service:store');
return run(() => {
return store.createRecord('user', { name: 'Dummy User'});
});
};
let generateDummyPost = container => {
const store = container.lookup('service:store');
return run(() => {
return store.createRecord('post');
});
};
test('it exists', function (assert) {
let service = this.subject();
assert.ok(service);
});
test('should delete the user', function (assert) {
let service = this.subject();
run(() => {
const userRecord = generateDummyUser(this.container);
service.deleteUserAndAssociatedData(userRecord);
assert.equal(userRecord.get('isDeleted'), true, 'the user is deleted');
});
});
test('should delete posts of the user', function (assert) {
let service = this.subject();
run(() => {
const userRecord = generateDummyUser(this.container);
const postRecord = generateDummyPost(this.container);
userRecord.get('posts').pushObject(postRecord);
return run(() => {
service.deleteUserAndAssociatedData(userRecord);
assert.equal(postRecord.get('isDeleted'), true, 'the post is deleted');
})
});
});
But the tests fail on the first assertion already with the following error:
Assertion Failed: calling set on destroyed object: .isSynced = false"
Is there anyone who can point me in the right direction? Maybe I should stub the adapter? Spy on the destroyRecord method?