SeleniumHQ/selenium · error · ArgumentError

expected #{rectangle.inspect}:#{rectangle.class} to respond

Error message

expected #{rectangle.inspect}:#{rectangle.class} to respond to #x, #y, #width, and #height

What it means

Raised by Window#rect= (ArgumentError) when the rectangle argument does not respond to all of x, y, width, and height. Validation iterates %w[x y width height] through respond_to? before delegating to bridge.set_window_rect.

Source

Thrown at rb/lib/selenium/webdriver/common/window.rb:89

      #
      # Get the position of the current window.
      #
      # @return [Selenium::WebDriver::Point] The position.
      #

      def position
        @bridge.window_position
      end

      #
      # Sets the current window rect to the given point and position.
      #
      # @param [Selenium::WebDriver::Rectangle, #x, #y, #width, #height] rectangle The new rect.
      #

      def rect=(rectangle)
        unless %w[x y width height].all? { |val| rectangle.respond_to? val }
          raise ArgumentError, "expected #{rectangle.inspect}:#{rectangle.class} " \
                               'to respond to #x, #y, #width, and #height'
        end

        @bridge.set_window_rect(x: rectangle.x,
                                y: rectangle.y,
                                width: rectangle.width,
                                height: rectangle.height)
      end

      #
      # Get the rect of the current window.
      #
      # @return [Selenium::WebDriver::Rectangle] The rectangle.
      #

      def rect
        @bridge.window_rect
      end

View on GitHub (pinned to aa36b38e69)

Solutions

1. Pass Selenium::WebDriver::Rectangle.new(x, y, width, height).
2. If you only have partial data, fill the missing fields (e.g. fetch current rect first and merge).
3. Avoid passing Hashes or Arrays; convert them into a Rectangle (or duck-typed object with all four accessors).

Example fix

// before
driver.manage.window.rect = {x: 0, y: 0, width: 800, height: 600}

// after
driver.manage.window.rect = Selenium::WebDriver::Rectangle.new(0, 0, 800, 600)

def rectangle_like?(obj)
  %w[x y width height].all? { |m| obj.respond_to?(m) }
end

raise ArgumentError, 'invalid rectangle' unless rectangle_like?(rect)
driver.manage.window.rect = rect

def rectangle_like?(obj)
  %w[x y width height].all? { |m| obj.respond_to?(m) }
end

When it happens

Trigger: Passing a Dimension (has width/height only), a Point (x/y only), a hash, an array, or a partial struct to driver.manage.window.rect =.

Common situations: Reusing a Dimension or Point object where a full Rectangle is required; passing a Hash with symbol keys (hashes don't respond to x/y/width/height as methods); constructing rects from JSON without wrapping in a Rectangle.

Related errors

• expected #{dimension.inspect}:#{dimension.class} to respond
• expected #{point.inspect}:#{point.class} to respond to #x an
• Valid types are :tab and :window, received: #{type.inspect}
• incompatible proxy type #{type.inspect} (already set to #{@t
• cannot find element by #{how.inspect}

AI-assisted analysis of SeleniumHQ/selenium@aa36b38e69 (2026-08-14). Data as JSON: /api/errors/7661e9914a10614c. Report an issue: GitHub.