[Rails] Unit testing + instance variables

[Jeremy Kemper]

Belorion wrote:
> After *much* digging and playing around, I finally figured out how to
> unit test instance variables that are created by actions.  It  was
> more difficult than I expected.  It seems like there should have been
> a more straight forward way to do this.  Can someone enlighten me?  A
> simplified and somewhat contrived example of what I am current doing:
> 
>     def test_list
>         get :list
>         # This step seems exessively complex, and took me a while to figure out
>         my_inst_vars  = @controller.instance_variable_get "@assigns"
> 
>         assert_equal( 5, my_inst_vars["recipes"].size )
>         assert_equal( 8, my_inst_vars["categories"].size )
>     end
> end

These assertions test instance variables passed to the view from the
controller:
  assert_template_has
  assert_template_has_no
  assert_assigned_equals
See http://manuals.rubyonrails.com/read/chapter/28#page78

However, they don't allow you to manipulate the instance variables.  You
can pull them directly from the response instead:

  def test_list
    assert_equal 5, @response.template.assigns['recipes'].size
    assert_equal 8, @response.template.assigns['categories'].size
  end

Test::Unit::TestCase#assigns would be a convenient enhancement.

  def test_list
    assert_equal 5, assigns(:recipes).size
    assert_equal 8, assigns(:categories).size
  end

  protected
    def assigns(name)
      @response.template.assigns[name.to_s]
    end

jeremy