Ember Mirage retreving DB Data

i have problem with retreving data in unit test from store by service method. Here is my code:

This is my test:

import { moduleFor, test } from 'ember-qunit';
import startMirage from '../../helpers/setup-mirage-for-integration';

moduleFor('service:filter-by-ingredients', 'Unit | Service | filter by ingredients', {
  needs: ['model:recipe', 'model:category'],
  beforeEach() {
    startMirage(this.container);
  },
  afterEach() {
    window.server.shutdown();
  }
});

test('should find recipe with title', async function(assert) {
  let recipe = server.create('recipe', {
    categories: server.createList('category', 5),
  })
  let service = this.subject();
  let result = await service.findRecipesWithContent();
  assert.equal(result.get('firstObject').get('categories').get('firstObject'), 10);
});

This is my service:

import Service from '@ember/service';
import { inject as service } from '@ember/service'

export default Service.extend({
  store: service(),
  findRecipesByWithContent() {
    return this.get('store').findAll('recipe');
  }
});

My mirage config:

  export default function() {

  this.get('/recipes', function(schema){
    return schema.recipes.all();
  });

  this.get('/categories', function(schema){
    return schema.categories.all();
  });

  this.post('/recipes', (schema, request) => {
    const attrs = JSON.parse(request.requestBody);
    return schema.recipes.create(attrs);
  });

  this.post('/categories', (schema, request) => {
    const attrs = JSON.parse(request.requestBody);
    return schema.categories.create(attrs);
  });
}

My factories:

import { Factory, faker, hasMany } from 'ember-cli-mirage';

export default Factory.extend({
  title: faker.list.random('omelette', 'chicken with salad', 'toasts', 'risotto', 'penne', 'spaghetti'),
  portionAmount: faker.list.random(1, 2, 3, 4, 5, 6),
  preparationTime: faker.list.random(5, 10, 15, 30, 45, 60),
  description: 'this is the description',
  calories: faker.list.random(100, 150, 200, 300, 400, 500),
  categories: hasMany('category'),
  rating: faker.list.random(1, 2, 3, 4, 5, 6),
});

Category factory

import { Factory, faker } from 'ember-cli-mirage';

export default Factory.extend({
  name: faker.list.random('dinner', 'breakfast', 'vegan', 'vegetarian', 'supper'),
});

And finally my models:

category

import DS from 'ember-data';

export default DS.Model.extend({
  name: DS.attr()
});

recipes

import DS from 'ember-data';
import { hasMany } from 'ember-data/relationships';

export default DS.Model.extend({
  title: DS.attr(),
  portionAmount: DS.attr(),
  preparationTime: DS.attr('number'),
  description: DS.attr(),
  calories: DS.attr('number'),
  categories: hasMany('category', { async: true }),
  rating: DS.attr(),
});

If i print:

console.log(server.db.recipes)

It shows all recipes with categories, one in my case, but when i call

service method findRecipeWithContent(), result.get('firstObject').get(categories).get('length') 

is 0. I can't get to this relationships.

If anyone can help me i would be very gratefull. Greetings!