diff --git a/actionpack/CHANGELOG.md b/actionpack/CHANGELOG.md
index 4fecd38e3dacf8b4a3d92ffb2a06e258712ed8a9..c8f11027765d536ccf9816c46d64dde7cf00210b 100644
--- a/actionpack/CHANGELOG.md
+++ b/actionpack/CHANGELOG.md
@@ -1,5 +1,11 @@
 ## Rails 4.0.0 (unreleased) ##
 
+*   Rename internal variables on ActionController::TemplateAssertions to prevent
+    naming collisions. @partials, @templates and @layouts are now prefixed with an underscore.
+    Fix #7459
+
+    *Yves Senn*
+
 *   `resource` and `resources` don't modify the passed options hash
     Fix #7777
 
diff --git a/actionpack/lib/action_controller/test_case.rb b/actionpack/lib/action_controller/test_case.rb
index 20c6e2bf53d729f38214341a62791437196e5578..3af378173ab1c1d27728bb7be23c4e3b315c472e 100644
--- a/actionpack/lib/action_controller/test_case.rb
+++ b/actionpack/lib/action_controller/test_case.rb
@@ -12,16 +12,16 @@ module TemplateAssertions
     end
 
     def setup_subscriptions
-      @partials = Hash.new(0)
-      @templates = Hash.new(0)
-      @layouts = Hash.new(0)
+      @_partials = Hash.new(0)
+      @_templates = Hash.new(0)
+      @_layouts = Hash.new(0)
 
       ActiveSupport::Notifications.subscribe("render_template.action_view") do |name, start, finish, id, payload|
         path = payload[:layout]
         if path
-          @layouts[path] += 1
+          @_layouts[path] += 1
           if path =~ /^layouts\/(.*)/
-            @layouts[$1] += 1
+            @_layouts[$1] += 1
           end
         end
       end
@@ -32,11 +32,11 @@ def setup_subscriptions
         partial = path =~ /^.*\/_[^\/]*$/
 
         if partial
-          @partials[path] += 1
-          @partials[path.split("/").last] += 1
+          @_partials[path] += 1
+          @_partials[path.split("/").last] += 1
         end
 
-        @templates[path] += 1
+        @_templates[path] += 1
       end
     end
 
@@ -46,9 +46,9 @@ def teardown_subscriptions
     end
 
     def process(*args)
-      @partials = Hash.new(0)
-      @templates = Hash.new(0)
-      @layouts = Hash.new(0)
+      @_partials = Hash.new(0)
+      @_templates = Hash.new(0)
+      @_layouts = Hash.new(0)
       super
     end
 
@@ -88,7 +88,7 @@ def assert_template(options = {}, message = nil)
       case options
       when NilClass, Regexp, String, Symbol
         options = options.to_s if Symbol === options
-        rendered = @templates
+        rendered = @_templates
         msg = message || sprintf("expecting <%s> but rendering with <%s>",
                 options.inspect, rendered.keys)
         matches_template =
@@ -109,15 +109,15 @@ def assert_template(options = {}, message = nil)
         if options.key?(:layout)
           expected_layout = options[:layout]
           msg = message || sprintf("expecting layout <%s> but action rendered <%s>",
-                  expected_layout, @layouts.keys)
+                  expected_layout, @_layouts.keys)
 
           case expected_layout
           when String, Symbol
-            assert_includes @layouts.keys, expected_layout.to_s, msg
+            assert_includes @_layouts.keys, expected_layout.to_s, msg
           when Regexp
-            assert(@layouts.keys.any? {|l| l =~ expected_layout }, msg)
+            assert(@_layouts.keys.any? {|l| l =~ expected_layout }, msg)
           when nil, false
-            assert(@layouts.empty?, msg)
+            assert(@_layouts.empty?, msg)
           end
         end
 
@@ -128,17 +128,17 @@ def assert_template(options = {}, message = nil)
               assert_equal(v, actual_locals[k])
             end
           elsif expected_count = options[:count]
-            actual_count = @partials[expected_partial]
+            actual_count = @_partials[expected_partial]
             msg = message || sprintf("expecting %s to be rendered %s time(s) but rendered %s time(s)",
                      expected_partial, expected_count, actual_count)
             assert(actual_count == expected_count.to_i, msg)
           else
             msg = message || sprintf("expecting partial <%s> but action rendered <%s>",
-                    options[:partial], @partials.keys)
-            assert_includes @partials, expected_partial, msg
+                    options[:partial], @_partials.keys)
+            assert_includes @_partials, expected_partial, msg
           end
         elsif options.key?(:partial)
-          assert @partials.empty?,
+          assert @_partials.empty?,
             "Expected no partials to be rendered"
         end
       else
diff --git a/actionpack/lib/action_view/test_case.rb b/actionpack/lib/action_view/test_case.rb
index b7fd6ec7e1738267d64310dbdc2732326fdf8b21..5434b3421e50e97f4cec3c53be061e0770b56615 100644
--- a/actionpack/lib/action_view/test_case.rb
+++ b/actionpack/lib/action_view/test_case.rb
@@ -196,17 +196,17 @@ def view
         :@_result,
         :@_routes,
         :@controller,
-        :@layouts,
+        :@_layouts,
         :@locals,
         :@method_name,
         :@output_buffer,
-        :@partials,
+        :@_partials,
         :@passed,
         :@rendered,
         :@request,
         :@routes,
         :@tagged_logger,
-        :@templates,
+        :@_templates,
         :@options,
         :@test_passed,
         :@view,