adding that assert_template with :layout will raise ArgumentError for unknown layout type

actionpack/lib/action_controller/test_case.rb

@@ -145,6 +145,8 @@ def assert_template(options = {}, message = nil)
             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
 

actionpack/test/controller/action_pack_assertions_test.rb

@@ -575,6 +575,13 @@ def test_fails_expecting_no_layout
     end
   end
 
+  def test_fails_expecting_not_known_layout
+    get :render_with_layout
+    assert_raise(ArgumentError) do
+      assert_template :layout => 1
+    end
+  end
+
   def test_passes_with_correct_layout
     get :render_with_layout
     assert_template :layout => "layouts/standard"