title: Test Migrations are not running with my Rails Engine, even though `maintain_test_schema!` is specified
body: <p>I'm developing a Rails Engine (Plugin). So far I have </p>
  
  <ul>
  <li>Set up RSpec as a framework</li>
  <li>Added a migration to create a model/table called <code>MyJob</code></li>
  <li>Added some basic model tests under <code>spec/models/my_job_spec.rb</code></li>
  </ul>
  
  <p>The rails template automatically creates a <code>spec/dummy</code> app, so I did the following to run my test</p>
  
  <pre><code># Create the development and test DBs
  rake db:create
  
  # Copy migrations over to my dummy app
  cd spec/dummy
  rake my_app:install:migrations
  cd ../..
  
  # Run specs
  rspec spec/models/my_job_spec.rb
  </code></pre>
  
  <p>However when I run my specs, I get an error: </p>
  
  <pre><code>&gt; rspec spec/models/
  /Users/jeeves/.rvm/gems/ruby-2.2.2@gb/gems/activerecord-5.1.0/lib/active_record/migration.rb:576:in `check_pending!':  (ActiveRecord::PendingMigrationError)
  
  Migrations are pending. To resolve this issue, run:
  
          bin/rails db:migrate RAILS_ENV=test
  </code></pre>
  
  <p>I thought this automatically would happen because in my <code>rails_helper.rb</code> I definitely have the following, which is supposed to maintain my test schema for me</p>
  
  <pre><code>ActiveRecord::Migration.maintain_test_schema!
  </code></pre>
  
  <p>Does it work differently with plugins or engines? </p>
  
  <p><em>EDIT:</em> I tried the recommendation of running <code>bin/rails db:migrate RAILS_ENV=test</code>, inside <code>spec/dummy/</code> and then re-running <code>rspec spec/</code>. Still no luck.</p>