Ember Data: Data becoming unlinked

mirage.config.js

export default function() {
  //window.server = this;
  this.get('authors/:id');

};

mirage.scenarios.default.js

export default function(server) {
  
  let author = server.create('author', {
    name: 'John Steinbeck'
  });
  
  ['Of Mice and Men', 'The Grapes of Wrath', 'Travels with Charley'].forEach(title => {
    server.create('author-book', {
      book: server.create('book', { title, isPublished: true }),
      author
    });
  });
  
}

mirage.serializers.application.js

import { JSONAPISerializer } from 'ember-cli-mirage';

export default JSONAPISerializer.extend({
});

mirage.serializers.author-book.js

import { JSONAPISerializer } from 'ember-cli-mirage';

export default JSONAPISerializer.extend({
  links() {
    return {
      book: {
        self: '/some/url',
        related: '/some/url'
      }
    };
  }
});

mirage.serializers.author.js

import { JSONAPISerializer } from 'ember-cli-mirage';

export default JSONAPISerializer.extend({
  links() {
    return {
      authorBooks: {
        self: '/some/url',
        related: '/some/url'
      }
    };
  }
});

models.author-book.js

import DS from 'ember-data';

export default DS.Model.extend({
  author: DS.belongsTo({ async: false }),
  book: DS.belongsTo({ async: false })
});

models.author.js

import DS from 'ember-data';
import Ember from 'ember';

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

  authorBooks: DS.hasMany('author-book', { async: false }),
  books: Ember.computed.mapBy('authorBooks', 'book'),
  publishedBooks: Ember.computed('books.@each.isPublished', function() {
    let books = this.get('books');
    console.log(books);

    return books.filterBy('isPublished');
  })

});

models.book.js

import DS from 'ember-data';

export default DS.Model.extend({
  title: DS.attr(),
  isPublished: DS.attr(),
  
  authorBooks: DS.hasMany('author-book', { async: false })
});

routes.application.js

import Ember from 'ember';

export default Ember.Route.extend({

  beforeModel() {
    return this.store.findRecord('author', 1, {
      include: 'author-books.book',
      reload: true
    });
  },
  
  model() {
    // CHANGEME
    let showBug = true;

    if (!showBug) {
      // Reloading the author is fine...
      return this.store.findRecord('author', 1, {
        include: 'author-books.book',
        reload: true
      });
      
    } else {
      // But if we reload the author without including author-books.book,
      //the existing books are disassociated from the author
      return this.store.findRecord('author', 1, {
        include: 'author-books',
        reload: true
      });
    }
  },
  
  afterModel(author) {
    let books = author.get('authorBooks').mapBy('book');
    
    // The bug is that author.authorBooks.mapBy('book') is null,
    // even though the data was there from beforeModel.
    //
    // The book link in the response payload is overriding the relationship.
    console.log('The authors books:');
    console.log(books);
  }
  
});

styles.app.css

body {
  margin: 0;
  font-family: 'Helvetica Neue', Helvetica, Arial, sans-serif;
  font-size: 12pt;
}

h1 {
  font-size: 12px;
  font-weight: bold;
  text-align: center;
  text-shadow: none;
  background: #2e4068;
  color: white;
  padding: 20px;
  margin: 0;
  text-transform: uppercase;
}

p {
  font-weight: normal;
}

.pa4 {
  padding: 20px;
}
hr {
  border-top: none;
  border-bottom: 1px solid #ddd;
}
button {
  padding: 10px 20px;
  background: #3490DC;
  color: white;
  box-shadow: 0 2px 0px 0px #1C3D5A;
  border: none;
  border-radius: 2px;
  cursor: pointer;
}
button:hover {
  background: #2779BD;
}

templates.application.hbs

<h1>Mirage boilerplate</h1>

<div class='pa4'>

  <p>
    Open the console.
  </p>



  
</div>

tests.acceptance.my-acceptance-test.js

import { test } from 'qunit';
import moduleForAcceptance from '../../tests/helpers/module-for-acceptance';

moduleForAcceptance('Acceptance | Users');

test('I can see the users', function(assert) {
  server.create('user', { name: 'Link' });
  
  //visit('/');

  andThen(function() {
    assert.ok(true);
    //assert.ok(find(':contains(Welcome Link!)').length);
  });
});

tests.helpers.destroy-app.js

import Ember from 'ember';

export default function destroyApp(application) {
  Ember.run(application, 'destroy');
}

tests.helpers.module-for-acceptance.js

import { module } from 'qunit';
import startApp from '../helpers/start-app';
import destroyApp from '../helpers/destroy-app';

export default function(name, options = {}) {
  module(name, {
    beforeEach() {
      this.application = startApp();

      if (options.beforeEach) {
        options.beforeEach.apply(this, arguments);
      }
    },

    afterEach() {
      if (options.afterEach) {
        options.afterEach.apply(this, arguments);
      }

      destroyApp(this.application);
    }
  });
}

tests.helpers.resolver.js

import Resolver from '../../resolver';
import config from '../../config/environment';

const resolver = Resolver.create();

resolver.namespace = {
  modulePrefix: config.modulePrefix,
  podModulePrefix: config.podModulePrefix
};

export default resolver;

tests.helpers.start-app.js

import Ember from 'ember';
import Application from '../../app';
import config from '../../config/environment';

export default function startApp(attrs) {
  let application;

  let attributes = Ember.merge({rootElement: "#test-root"}, config.APP);
  attributes = Ember.merge(attributes, attrs); // use defaults, but you can override;

  Ember.run(() => {
    application = Application.create(attributes);
    application.setupForTesting();
    application.injectTestHelpers();
  });

  return application;
}

tests.test-helper.js

import resolver from './helpers/resolver';
import {
  setResolver
} from 'ember-qunit';

setResolver(resolver);

twiddle.json

{
  "version": "0.13.1",
  "ENV": {
    "ember-cli-mirage": {
      "enabled": true
    }
  },
  "EmberENV": {
    "FEATURES": {}
  },
  "options": {
    "use_pods": false,
    "enable-testing": false
  },
  "dependencies": {
    "jquery": "https://cdnjs.cloudflare.com/ajax/libs/jquery/1.11.3/jquery.js",
    "ember": "2.16.2",
    "ember-template-compiler": "2.16.2",
    "ember-testing": "2.16.2"
  },
  "addons": {
    "ember-data": "2.16.3",
    "ember-cli-mirage": "0.4.7"
  }
}