1 files changed, 27 insertions, 2 deletions
diff --git a/actionpack/lib/action_controller/test_case.rb b/actionpack/lib/action_controller/test_case.rb
index 8c10c3e7b0..9a77f179d3 100644
--- a/actionpack/lib/action_controller/test_case.rb
+++ b/actionpack/lib/action_controller/test_case.rb
@@ -2,6 +2,7 @@ require 'rack/session/abstract/id'
 require 'active_support/core_ext/object/to_query'
 require 'active_support/core_ext/module/anonymous'
 require 'active_support/core_ext/hash/keys'
+require 'active_support/deprecation'
 
 require 'rails-dom-testing'
 
@@ -66,7 +67,8 @@ module ActionController
 
     def reset_template_assertion
       RENDER_TEMPLATE_INSTANCE_VARIABLES.each do |instance_variable|
-        instance_variable_get("@_#{instance_variable}").clear
+        ivar = instance_variable_get("@_#{instance_variable}")
+        ivar.clear if ivar
       end
     end
 
@@ -144,6 +146,8 @@ module ActionController
             assert(@_layouts.keys.any? {|l| l =~ expected_layout }, msg)
           when nil, false
             assert(@_layouts.empty?, msg)
+          else
+            raise ArgumentError, "assert_template only accepts a String, Symbol, Regexp, nil or false for :layout"
           end
         end
 
@@ -710,7 +714,28 @@ module ActionController
             :relative_url_root => nil,
             :_recall => @request.path_parameters)
 
-          url, query_string = @routes.path_for(options).split("?", 2)
+          if route_name = options.delete(:use_route)
+            ActiveSupport::Deprecation.warn <<-MSG.squish
+              Passing the `use_route` option in functional tests are deprecated.
+              Support for this option in the `process` method (and the related
+              `get`, `head`, `post`, `patch`, `put` and `delete` helpers) will
+              be removed in the next version without replacement.
+
+              Functional tests are essentially unit tests for controllers and
+              they should not require knowledge to how the application's routes
+              are configured. Instead, you should explicitly pass the appropiate
+              params to the `process` method.
+
+              Previously the engines guide also contained an incorrect example
+              that recommended using this option to test an engine's controllers
+              within the dummy application. That recommendation was incorrect
+              and has since been corrected. Instead, you should override the
+              `@routes` variable in the test case with `Foo::Engine.routes`. See
+              the updated engines guide for details.
+            MSG
+          end
+
+          url, query_string = @routes.path_for(options, route_name).split("?", 2)
 
           @request.env["SCRIPT_NAME"] = @controller.config.relative_url_root
           @request.env["PATH_INFO"] = url