my_app_test.js

import { test } from 'qunit';
import Pretender from 'pretender';
import moduleForAcceptance from 'my-app/tests/helpers/module-for-acceptance';

export function json(status, payload) {
  return [
    status,
    { 'Content-Type': 'application/json; charset=utf-8' },
    JSON.stringify(payload)
  ];
}

moduleForAcceptance('Acceptance | post-viewer', {
  beforeEach() {
    this.server = new Pretender();
  },
  afterEach() {
    this.server.shutdown();
  }
});

test('visiting /post-viewer/:post_id', function(assert) {
  this.server.get('my_api/posts/123', function() {
    return json(200, {
      id: '123',
      title: 'Rails is Omakase',
      body: '...'
    });
  });

  visit('/post-viewer/123');

  andThen(function() {
    assert.equal(currentURL(), '/post-viewer/123');
    findWithAssert(`.post-title:contains('Rails is Omakase'`);
  });
});