save_to_disk(Lines, Filename)

      save_to_disk(Lines, Filename)

function test_undo_name_point()
  io.write('\ntest_undo_name_point')
  -- create a drawing with a line
  Filename = 'foo'
  App.screen.init{width=Margin_left+300, height=300}
  Lines = load_array{'```lines', '```', ''}
  Line_width = 256  -- drawing coordinates 1:1 with pixels
  Current_drawing_mode = 'line'
  App.draw()
  -- draw a line
  App.run_after_mouse_press(Margin_left+5, Margin_top+Drawing_padding_top+6, 1)
  App.run_after_mouse_release(Margin_left+35, Margin_top+Drawing_padding_top+36, 1)
  local drawing = Lines[1]
  check_eq(#drawing.shapes, 1, 'F - test_undo_name_point/baseline/#shapes')
  check_eq(#drawing.points, 2, 'F - test_undo_name_point/baseline/#points')
  check_eq(drawing.shapes[1].mode, 'line', 'F - test_undo_name_point/baseline/shape:1')
  local p1 = drawing.points[drawing.shapes[1].p1]
  local p2 = drawing.points[drawing.shapes[1].p2]
  check_eq(p1.x, 5, 'F - test_undo_name_point/baseline/p1:x')
  check_eq(p1.y, 6, 'F - test_undo_name_point/baseline/p1:y')
  check_eq(p2.x, 35, 'F - test_undo_name_point/baseline/p2:x')
  check_eq(p2.y, 36, 'F - test_undo_name_point/baseline/p2:y')
  check_nil(p2.name, 'F - test_undo_name_point/baseline/p2:name')
  check_eq(#History, 1, 'F - test_undo_name_point/baseline/history:1')
  -- enter 'name' mode without moving the mouse
  App.run_after_keychord('C-n')
  App.run_after_textinput('A')
  App.run_after_keychord('return')
  check_eq(p2.name, 'A', 'F - test_undo_name_point/baseline')
  check_eq(#History, 3, 'F - test_undo_name_point/baseline/history:2')
  check_eq(Next_history, 4, 'F - test_undo_name_point/baseline/next_history')
  -- undo
  App.run_after_keychord('C-z')
  local drawing = Lines[1]
  local p2 = drawing.points[drawing.shapes[1].p2]
  check_eq(Next_history, 3, 'F - test_undo_name_point/next_history')
  check_eq(p2.name, '', 'F - test_undo_name_point')  -- not quite what it was before, but close enough
  -- change is saved
  Lines = load_from_disk(Filename)
  local p2 = Lines[1].points[drawing.shapes[1].p2]
  check_eq(p2.name, '', 'F - test_undo_name_point/save')
end

  naming points