How to make RSpec recognize slim templates?
<p>I have a trivialized controller action in a module</p>

<pre><code>module MyEngine
  module UsersControllerExt
    extend ActiveSupport::Concern

    def index
      @users = User.relevant
      render template: "users/index"
    end

  end
end
</code></pre>

<p>And an RSpec controller concern spec using anonymous controller</p>

<pre><code>RSpec.describe MyEngine::UsersControllerExt, type: :controller do
  controller(ApplicationController) do
    include MyEngine::UsersControllerExt
  end

  describe "GET :show" do
    it "should set @users instance variable" do
      get :index

      expect(assigns(:users)).to be_present      
    end
  end

end
</code></pre>

<p>This spec fails with</p>

<pre><code>ActionView::MissingTemplate:
   Missing template users/index with {:locale=&gt;[:en], :formats=&gt;[:html], :variants=&gt;[], :handlers=&gt;[:erb, :builder, :raw, :ruby]}. Searched in:
     * "~/Documents/my_engine/spec/dummy/app/views"
     * "~/Documents/my_engine/app/views"
</code></pre>

<p>If I change the template file <code>index.slim</code> to <code>index.erb</code>, the spec passes.<br>
How do I make RSpec accept slim templates?</p>