image_tag raises an error if size is passed with height and/or width

actionview/lib/action_view/helpers/asset_tag_helper.rb

@@ -207,6 +207,7 @@ def favicon_link_tag(source='favicon.ico', options={})
       #   # => <img alt="Icon" class="menu_icon" src="/icons/icon.gif" />
       def image_tag(source, options={})
         options = options.symbolize_keys
+        check_for_image_tag_errors(options)
 
         src = options[:src] = path_to_image(source)
 
@@ -325,6 +326,12 @@ def extract_dimensions(size)
             [size, size]
           end
         end
+
+        def check_for_image_tag_errors(options)
+          if options[:size] && (options[:height] || options[:width])
+            raise ArgumentError, "Cannot pass a :size option with a :height or :width option"
+          end
+        end
     end
   end
 end

actionview/test/template/asset_tag_helper_test.rb

@@ -464,6 +464,14 @@ def test_image_tag_does_not_modify_options
     assert_equal({:size => '16x10'}, options)
   end
 
+  def test_image_tag_raises_an_error_for_competing_size_arguments
+    exception = assert_raise(ArgumentError) do
+      image_tag("gold.png", :height => "100", :width => "200", :size => "45x70")
+    end
+
+    assert_equal("Cannot pass a :size option with a :height or :width option", exception.message)
+  end
+
   def test_favicon_link_tag
     FaviconLinkToTag.each { |method, tag| assert_dom_equal(tag, eval(method)) }
   end