refile file upload using rspec and fixture file upload

gistfile1.rb

describe "post #upload" do
  it "image to object" do
    container = create :container
    file = fixture_file_upload(Rails.root.join('spec/fixtures/files/example.jpg'), 'image/jpeg')
    container.attached_image = file
    post :upload, container: container.to_param
    expect(container.reload.attached_image).to be_present
  end
end

Little bit different approach:

describe "Image Uploads" do
  describe User do
    let(:user) { create :user }
    it 'should be possible to create a profile image for a user' do
      user.profile_image = File.open(File.join(Rails.root, 'db/seeds/aist.png'))
      expect(user.profile_image.id).to be_truthy
    end
  end
end