function test_resize_window()
  App.screen.init{width=300, height=300}
  Editor_state = edit.initialize_test_state()
  Editor_state.filename = 'foo'
  check_eq(App.screen.width, 300, 'baseline/width')
  check_eq(App.screen.height, 300, 'baseline/height')
  check_eq(Editor_state.left, Test_margin_left, 'baseline/left_margin')
  check_eq(Editor_state.right, 300 - Test_margin_right, 'baseline/left_margin')
  App.resize(200, 400)
  -- ugly; resize switches to real, non-test margins
  check_eq(App.screen.width, 200, 'width')
  check_eq(App.screen.height, 400, 'height')
  check_eq(Editor_state.left, Margin_left, 'left_margin')
  check_eq(Editor_state.right, 200-Margin_right, 'right_margin')
  check_eq(Editor_state.width, 200-Margin_left-Margin_right, 'drawing_width')
  -- TODO: how to make assertions about when App.update got past the early exit?
end