TestCase should respect the view_assigns API instead of pulling variables on its own.

actionpack/lib/abstract_controller/rendering.rb

@@ -120,8 +120,6 @@ def _render_template(options) #:nodoc:
       view_renderer.render(view_context, options)
     end
 
-    private
-
     DEFAULT_PROTECTED_INSTANCE_VARIABLES = %w(
       @_action_name @_response_body @_formats @_prefixes @_config
       @_view_context_class @_view_renderer @_lookup_context
@@ -139,6 +137,8 @@ def view_assigns
       hash
     end
 
+    private
+
     # Normalize args and options.
     # :api: private
     def _normalize_render(*args, &block)

actionpack/lib/action_dispatch/testing/test_process.rb

@@ -5,12 +5,7 @@
 module ActionDispatch
   module TestProcess
     def assigns(key = nil)
-      assigns = {}.with_indifferent_access
-      @controller.instance_variable_names.each do |ivar|
-        next if ActionController::Base.protected_instance_variables.include?(ivar)
-        assigns[ivar[1..-1]] = @controller.instance_variable_get(ivar)
-      end
-
+      assigns = @controller.view_assigns.with_indifferent_access
       key.nil? ? assigns : assigns[key]
     end
 

actionpack/test/controller/test_test.rb

@@ -146,6 +146,17 @@ def setup
     end
   end
 
+  class ViewAssignsController < ActionController::Base
+    def test_assigns
+      @foo = "foo"
+      render :nothing => true
+    end
+
+    def view_assigns
+      { "bar" => "bar" }
+    end
+  end
+
   def test_raw_post_handling
     params = ActiveSupport::OrderedHash[:page, {:name => 'page name'}, 'some key', 123]
     post :render_raw_post, params.dup
@@ -256,6 +267,15 @@ def test_assigns
     assert_equal "foo", assigns["foo"]
   end
 
+  def test_view_assigns
+    @controller = ViewAssignsController.new
+    process :test_assigns
+    assert_equal nil, assigns(:foo)
+    assert_equal nil, assigns[:foo]
+    assert_equal "bar", assigns(:bar)
+    assert_equal "bar", assigns[:bar]
+  end
+
   def test_assert_tag_tag
     process :test_html_output