local infile = io.open(filename)

  local infile = App.open_for_reading(filename)

function test_creating_drawing_saves()
  io.write('\ntest_creating_drawing_saves')
  App.screen.init{width=120, height=60}
  Filename = 'foo'
  Lines = load_array{}
  App.draw()
  -- click on button to create drawing
  App.run_after_mouse_click(8,Margin_top+8, 1)
  -- filesystem contains drawing and an empty line of text
  check_eq(App.filesystem['foo'], '```lines\n```\n\n', 'F - test_creating_drawing_saves')
end

  Filename = 'foo'

  -- The format on disk isn't perfectly stable. Table fields can be reordered.
  -- So just reload from disk to verify.
  Lines = load_from_disk(Filename)
  local drawing = Lines[1]
  check_eq(#drawing.shapes, 1, 'F - test_draw_line/save/#shapes')
  check_eq(#drawing.points, 2, 'F - test_draw_line/save/#points')
  check_eq(drawing.shapes[1].mode, 'line', 'F - test_draw_line/save/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_draw_line/save/p1:x')
  check_eq(p1.y, 6, 'F - test_draw_line/save/p1:y')
  check_eq(p2.x, 35, 'F - test_draw_line/save/p2:x')
  check_eq(p2.y, 36, 'F - test_draw_line/save/p2:y')

    write = function(self, s)
              App.filesystem[filename] = App.filesystem[filename]..s

    write = function(self, ...)
              local args = {...}
              for i,s in ipairs(args) do
                App.filesystem[filename] = App.filesystem[filename]..s
              end
            end,
    close = function(self)
            end
  }
end
function App.open_for_reading(filename)
  return {
    lines = function(self)
              return App.filesystem[filename]:gmatch('[^\n]+')

  App.open_for_reading = function(filename) return io.open(filename, 'r') end

  draw a line, circle, rectangle, square, polygon, quit, restart. All the shapes you drew should still be visible.