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Console

   (X) #0   09/12/06  console commands
   (X) #1   09/12/06  quick find
   (X) #2   09/12/06  open with
   (X) #4   09/12/06  history for console
   (X) #13  09/12/27  display docstring of a command


General

   (X) #5   09/12/06  move code from fm into objects
   (X) #6   09/12/06  move main to __init__
   (X) #7   09/12/06  cooler titlebar
   (X) #8   09/12/17  Add operations to modify files/directories
   (X) #9   09/12/24  add a widget for managing running operations
   (X) #10  09/12/24  sorting
   (X) #11  09/12/27  filter
   (X) #12  09/12/27  jump through the list in a specific order
   (X) #14  09/12/29  make filelists inherit from pagers
   (X) #15  09/12/29  better way of running processes!!~
   (X) #16  10/01/01  list of bookmarks
   (X) #21  10/01/01  write help!
   (X) #22  10/01/03  add getopt options to change flags/mode
   (X) #29  10/01/06  add chmod command
   (X) #30  10/01/06  add a way to create symlinks
   (X) #32  10/01/08  place the (hidden) cursor to a meaningful position
   (X) #34  10/01/09  display free disk space
   (X) #35  10/01/09  display disk usage of files in current directory
   ( ) #36  10/01/11  help coloring is terribly inefficient
   (X) #37  10/01/13  better tab completion for OpenConsole
   ( ) #38  10/01/16  searching in pager
   (X) #39  10/01/17  flushinput not always good
   (X) #42  10/01/17  memorize directory for `` when using :cd
   (X) #43  10/01/18  internally treat the bookmarks ` and ' the same
   ( ) #44  10/01/18  more error messages :P
   (X) #47  10/01/19  less restricive auto preview
   (X) #48  10/01/19  abbreviate commands with first unambiguous substring
   ( ) #50  10/01/19  add more unit tests
   ( ) #51  10/01/21  remove directory.marked_items ?
   (X) #55  10/01/24  allow change of filename when pasting
          you're given the choice between overwriting or appending a "_"
   ( ) #56  10/01/30  warn before deleting mount points
   ( ) #57  10/01/30  warn before deleting unseen marked files
   (X) #58  10/02/04  change the title of the terminal
   (X) #61  10/02/09  show sum of size of marked files
   (X) #63  10/02/15  limit filesize in previews
   ( ) #64  10/02/25  scroll in previews
   (X) #66  10/02/28  explain how colorschemes work
   (X) #70  10/03/14  mouse handler for titlebar
   (X) #71  10/03/21  previews: black/whitelist + read file
   (X) #79  10/04/08  tab number zero
   ( ) #80  10/04/08  when closing tabs, avoid gaps?
   (X) #81  10/04/15  system crash when previewing /proc/kcore with root permissions
   (X) #83  10/04/19  better ways to mark files. eg by regexp, filetype,..
   ( ) #86  10/04/21  narg for move_parent
   ( ) #60  10/02/05  utf support improvable
   ( ) #91  10/05/12  in keys.py, fm.move(right=N) should run with mode=N
   ( ) #92  10/05/14  allow to enter the realpath of a directory
   ( ) #93  10/05/15  pause after running program


Bugs

   (X) #17  10/01/01  why do bookmarks disappear sometimes?
   (X) #18  10/01/01  fix notify widget (by adding a LogView?)
   (X) #19  10/01/01  resizing after pressing g
   (X) #23  10/01/04  stop dir loading with ^C -> wont load anymore
   (X) #25  10/01/06  directories sometimes dont reload correctly
   (X) #26  10/01/06  :delete on symlinks of directories fails
   (X) #31  10/01/06  ^C breaks cd-after-exit by stopping sourced shell script
   (X) #40  10/01/17  freeze with unavailable sshfs
          Not rangers fault (?)
   (X) #41  10/01/17  capital file extensions are not recognized
   (X) #46  10/01/19  old username displayed after using su
   (X) #49  10/01/19  fix unit tests :'(
   (X) #52  10/01/23  special characters in tab completion
   (X) #54  10/01/23  max_dirsize_for_autopreview not working
   (X) #62  10/02/15  curs_set can raise an exception
   (X) #65  10/02/16  "source ranger ranger some/file.txt" shouldn't cd after exit
   (X) #67  10/03/08  terminal title in tty
   (X) #69  10/03/11  tab-completion breaks with Apps subclass
   (X) #73  10/03/21  when clicking on the first column, it goes 1x down
   (X) #74  10/03/21  console doesn't scroll
   (X) #78  10/03/31  broken preview when deleting all files in a directory
   (X) #85  10/04/26  no automatic reload of directory after using :filter
   (X) #87  10/05/10  files are not properly closed after previewing
   ( ) #88  10/05/10  race conditions for data loading from FS
   (X) #90  10/05/11  no link target for broken links
   ( ) #94  10/05/26  "pressed keys" text cut off when chaining ctrl-XYZ keys


Ideas

   ( ) #20  10/01/01  use inotify to monitor filesystem changes
   ( ) #24  10/01/06  progress bar
   (X) #27  10/01/06  hide bookmarks in list which contain hidden dir
   (X) #28  10/01/06  use regexp instead of string for searching
   (X) #33  10/01/08  accelerate mousewheel speed
          won't do this
   (X) #45  10/01/18  hooks for events like setting changes
   (X) #53  10/01/23  merge fm and environment
          won't do this
   (X) #68  10/03/10  threads, to seperate ui and loading
          won't do this
   ( ) #72  10/03/21  ranger daemon which does the slow io tasks
   ( ) #75  10/03/28  navigate in history
   (X) #76  10/03/28  save history between sessions
   (X) #77  10/03/28  colorscheme overlay in options.py
   ( ) #82  10/04/19  :s command for batch renaming
   ( ) #84  10/04/25  use pygments for syntax highlighting
   ( ) #89  10/05/10  branch view


Blocking

   ( ) #60  10/02/05  utf support improvable
   (X) #81  10/04/15  system crash when previewing /proc/kcore with root permissions
{ color: inherit; background-color: transparent; padding-left: 5px; padding-right: 5px; } span.linenos { color: inherit; background-color: transparent; padding-left: 5px; padding-right: 5px; } td.linenos .special { color: #000000; background-color: #ffffc0; padding-left: 5px; padding-right: 5px; } span.linenos.special { color: #000000; background-color: #ffffc0; padding-left: 5px; padding-right: 5px; } .highlight .hll { background-color: #ffffcc } .highlight .c { color: #888888 } /* Comment */ .highlight .err { color: #a61717; background-color: #e3d2d2 } /* Error */ .highlight .k { color: #008800; font-weight: bold } /* Keyword */ .highlight .ch { color: #888888 } /* Comment.Hashbang */ .highlight .cm { color: #888888 } /* Comment.Multiline */ .highlight .cp { color: #cc0000; font-weight: bold } /* Comment.Preproc */ .highlight .cpf { color: #888888 } /* Comment.PreprocFile */ .highlight .c1 { color: #888888 } /* Comment.Single */ .highlight .cs { color: #cc0000; font-weight: bold; background-color: #fff0f0 } /* Comment.Special */ .highlight .gd { color: #000000; background-color: #ffdddd } /* Generic.Deleted */ .highlight .ge { font-style: italic } /* Generic.Emph */ .highlight .ges { font-weight: bold; font-style: italic } /* Generic.EmphStrong */ .highlight .gr { color: #aa0000 } /* Generic.Error */ .highlight .gh { color: #333333 } /* Generic.Heading */ .highlight .gi { color: #000000; background-color: #ddffdd } /* Generic.Inserted */ .highlight .go { color: #888888 } /* Generic.Output */ .highlight .gp { color: #555555 } /* Generic.Prompt */ .highlight .gs { font-weight: bold } /* Generic.Strong */ .highlight .gu { color: #666666 } /* Generic.Subheading */ .highlight .gt { color: #aa0000 } /* Generic.Traceback */ .highlight .kc { color: #008800; font-weight: bold } /* Keyword.Constant */ .highlight .kd { color: #008800; font-weight: bold } /* Keyword.Declaration */ .highlight .kn { color: #008800; font-weight: bold } /* Keyword.Namespace */ .highlight .kp { color: #008800 } /* Keyword.Pseudo */ .highlight .kr { color: #008800; font-weight: bold } /* Keyword.Reserved */ .highlight .kt { color: #888888; font-weight: bold } /* Keyword.Type */ .highlight .m { color: #0000DD; font-weight: bold } /* Literal.Number */ .highlight .s { color: #dd2200; background-color: #fff0f0 } /* Literal.String */ .highlight .na { color: #336699 } /* Name.Attribute */ .highlight .nb { color: #003388 } /* Name.Builtin */ .highlight .nc { color: #bb0066; font-weight: bold } /* Name.Class */ .highlight .no { color: #003366; font-weight: bold } /* Name.Constant */ .highlight .nd { color: #555555 } /* Name.Decorator */ .highlight .ne { color: #bb0066; font-weight: bold } /* Name.Exception */ .highlight .nf { color: #0066bb; font-weight: bold } /* Name.Function */ .highlight .nl { color: #336699; font-style: italic } /* Name.Label */ .highlight .nn { color: #bb0066; font-weight: bold } /* Name.Namespace */ .highlight .py { color: #336699; font-weight: bold } /* Name.Property */ .highlight .nt { color: #bb0066; font-weight: bold } /* Name.Tag */ .highlight .nv { color: #336699 } /* Name.Variable */ .highlight .ow { color: #008800 } /* Operator.Word */ .highlight .w { color: #bbbbbb } /* Text.Whitespace */ .highlight .mb { color: #0000DD; font-weight: bold } /* Literal.Number.Bin */ .highlight .mf { color: #0000DD; font-weight: bold } /* Literal.Number.Float */ .highlight .mh { color: #0000DD; font-weight: bold } /* Literal.Number.Hex */ .highlight .mi { color: #0000DD; font-weight: bold } /* Literal.Number.Integer */ .highlight .mo { color: #0000DD; font-weight: bold } /* Literal.Number.Oct */ .highlight .sa { color: #dd2200; background-color: #fff0f0 } /* Literal.String.Affix */ .highlight .sb { color: #dd2200; background-color: #fff0f0 } /* Literal.String.Backtick */ .highlight .sc { color: #dd2200; background-color: #fff0f0 } /* Literal.String.Char */ .highlight .dl { color: #dd2200; background-color: #fff0f0 } /* Literal.String.Delimiter */ .highlight .sd { color: #dd2200; background-color: #fff0f0 } /* Literal.String.Doc */ .highlight .s2 { color: #dd2200; background-color: #fff0f0 } /* Literal.String.Double */ .highlight .se { color: #0044dd; background-color: #fff0f0 } /* Literal.String.Escape */ .highlight .sh { color: #dd2200; background-color: #fff0f0 } /* Literal.String.Heredoc */ .highlight .si { color: #3333bb; background-color: #fff0f0 } /* Literal.String.Interpol */ .highlight .sx { color: #22bb22; background-color: #f0fff0 } /* Literal.String.Other */ .highlight .sr { color: #008800; background-color: #fff0ff } /* Literal.String.Regex */ .highlight .s1 { color: #dd2200; background-color: #fff0f0 } /* Literal.String.Single */ .highlight .ss { color: #aa6600; background-color: #fff0f0 } /* Literal.String.Symbol */ .highlight .bp { color: #003388 } /* Name.Builtin.Pseudo */ .highlight .fm { color: #0066bb; font-weight: bold } /* Name.Function.Magic */ .highlight .vc { color: #336699 } /* Name.Variable.Class */ .highlight .vg { color: #dd7700 } /* Name.Variable.Global */ .highlight .vi { color: #3333bb } /* Name.Variable.Instance */ .highlight .vm { color: #336699 } /* Name.Variable.Magic */ .highlight .il { color: #0000DD; font-weight: bold } /* Literal.Number.Integer.Long */
-- major tests for text editing flows

function test_initial_state()
  io.write('\ntest_initial_state')
  App.screen.init{width=120, height=60}
  Editor_state = edit.initialize_test_state()
  Editor_state.lines = load_array{}
  Text.redraw_all(Editor_state)
  edit.draw(Editor_state)
  check_eq(#Editor_state.lines, 1, 'F - test_initial_state/#lines')
  check_eq(Editor_state.cursor1.line, 1, 'F - test_initial_state/cursor:line')
  check_eq(Editor_state.cursor1.pos, 1, 'F - test_initial_state/cursor:pos')
  check_eq(Editor_state.screen_top1.line, 1, 'F - test_initial_state/screen_top:line')
  check_eq(Editor_state.screen_top1.pos, 1, 'F - test_initial_state/screen_top:pos')
end

function test_backspace_from_start_of_final_line()
  io.write('\ntest_backspace_from_start_of_final_line')
  -- display final line of text with cursor at start of it
  App.screen.init{width=120, height=60}
  Editor_state = edit.initialize_test_state()
  Editor_state.lines = load_array{'abc', 'def'}
  Editor_state.screen_top1 = {line=2, pos=1}
  Editor_state.cursor1 = {line=2, pos=1}
  Text.redraw_all(Editor_state)
  -- backspace scrolls up
  edit.run_after_keychord(Editor_state, 'backspace')
  check_eq(#Editor_state.lines, 1, 'F - test_backspace_from_start_of_final_line/#lines')
  check_eq(Editor_state.cursor1.line, 1, 'F - test_backspace_from_start_of_final_line/cursor')
  check_eq(Editor_state.screen_top1.line, 1, 'F - test_backspace_from_start_of_final_line/screen_top')
end

function test_insert_first_character()
  io.write('\ntest_insert_first_character')
  App.screen.init{width=120, height=60}
  Editor_state = edit.initialize_test_state()
  Editor_state.lines = load_array{}
  Text.redraw_all(Editor_state)
  edit.draw(Editor_state)
  edit.run_after_textinput(Editor_state, 'a')
  local y = Editor_state.top
  App.screen.check(y, 'a', 'F - test_insert_first_character/screen:1')
end

function test_press_ctrl()
  io.write('\ntest_press_ctrl')
  -- press ctrl while the cursor is on text
  App.screen.init{width=50, height=80}
  Editor_state = edit.initialize_test_state()
  Editor_state.lines = load_array{''}
  Text.redraw_all(Editor_state)
  Editor_state.cursor1 = {line=1, pos=1}
  Editor_state.screen_top1 = {line=1, pos=1}
  Editor_state.screen_bottom1 = {}
  edit.run_after_keychord(Editor_state, 'C-m')
end

function test_move_left()
  io.write('\ntest_move_left')
  App.screen.init{width=120, height=60}
  Editor_state = edit.initialize_test_state()
  Editor_state.lines = load_array{'a'}
  Text.redraw_all(Editor_state)
  Editor_state.cursor1 = {line=1, pos=2}
  edit.draw(Editor_state)
  edit.run_after_keychord(Editor_state, 'left')
  check_eq(Editor_state.cursor1.pos, 1, 'F - test_move_left')
end

function test_move_right()
  io.write('\ntest_move_right')
  App.screen.init{width=120, height=60}
  Editor_state = edit.initialize_test_state()
  Editor_state.lines = load_array{'a'}
  Text.redraw_all(Editor_state)
  Editor_state.cursor1 = {line=1, pos=1}
  edit.draw(Editor_state)
  edit.run_after_keychord(Editor_state, 'right')
  check_eq(Editor_state.cursor1.pos, 2, 'F - test_move_right')
end

function test_move_left_to_previous_line()
  io.write('\ntest_move_left_to_previous_line')
  App.screen.init{width=120, height=60}
  Editor_state = edit.initialize_test_state()
  Editor_state.lines = load_array{'abc', 'def'}
  Text.redraw_all(Editor_state)
  Editor_state.cursor1 = {line=2, pos=1}
  edit.draw(Editor_state)
  edit.run_after_keychord(Editor_state, 'left')
  check_eq(Editor_state.cursor1.line, 1, 'F - test_move_left_to_previous_line/line')
  check_eq(Editor_state.cursor1.pos, 4, 'F - test_move_left_to_previous_line/pos')  -- past end of line
end

function test_move_right_to_next_line()
  io.write('\ntest_move_right_to_next_line')
  App.screen.init{width=120, height=60}
  Editor_state = edit.initialize_test_state()
  Editor_state.lines = load_array{'abc', 'def'}
  Text.redraw_all(Editor_state)
  Editor_state.cursor1 = {line=1, pos=4}  -- past end of line
  edit.draw(Editor_state)
  edit.run_after_keychord(Editor_state, 'right')
  check_eq(Editor_state.cursor1.line, 2, 'F - test_move_right_to_next_line/line')
  check_eq(Editor_state.cursor1.pos, 1, 'F - test_move_right_to_next_line/pos')
end

function test_move_to_start_of_word()
  io.write('\ntest_move_to_start_of_word')
  App.screen.init{width=120, height=60}
  Editor_state = edit.initialize_test_state()
  Editor_state.lines = load_array{'abc'}
  Text.redraw_all(Editor_state)
  Editor_state.cursor1 = {line=1, pos=3}
  edit.draw(Editor_state)
  edit.run_after_keychord(Editor_state, 'M-left')
  check_eq(Editor_state.cursor1.pos, 1, 'F - test_move_to_start_of_word')
end

function test_move_to_start_of_previous_word()
  io.write('\ntest_move_to_start_of_previous_word')
  App.screen.init{width=120, height=60}
  Editor_state = edit.initialize_test_state()
  Editor_state.lines = load_array{'abc def'}
  Text.redraw_all(Editor_state)
  Editor_state.cursor1 = {line=1, pos=4}  -- at the space between words
  edit.draw(Editor_state)
  edit.run_after_keychord(Editor_state, 'M-left')
  check_eq(Editor_state.cursor1.pos, 1, 'F - test_move_to_start_of_previous_word')
end

function test_skip_to_previous_word()
  io.write('\ntest_skip_to_previous_word')
  App.screen.init{width=120, height=60}
  Editor_state = edit.initialize_test_state()
  Editor_state.lines = load_array{'abc def'}
  Text.redraw_all(Editor_state)
  Editor_state.cursor1 = {line=1, pos=5}  -- at the start of second word
  edit.draw(Editor_state)
  edit.run_after_keychord(Editor_state, 'M-left')
  check_eq(Editor_state.cursor1.pos, 1, 'F - test_skip_to_previous_word')
end

function test_skip_past_tab_to_previous_word()
  io.write('\ntest_skip_past_tab_to_previous_word')
  App.screen.init{width=120, height=60}
  Editor_state = edit.initialize_test_state()
  Editor_state.lines = load_array{'abc def\tghi'}
  Text.redraw_all(Editor_state)
  Editor_state.cursor1 = {line=1, pos=10}  -- within third word
  edit.draw(Editor_state)
  edit.run_after_keychord(Editor_state, 'M-left')
  check_eq(Editor_state.cursor1.pos, 9, 'F - test_skip_past_tab_to_previous_word')
end

function test_skip_multiple_spaces_to_previous_word()
  io.write('\ntest_skip_multiple_spaces_to_previous_word')
  App.screen.init{width=120, height=60}
  Editor_state = edit.initialize_test_state()
  Editor_state.lines = load_array{'abc  def'}
  Text.redraw_all(Editor_state)
  Editor_state.cursor1 = {line=1, pos=6}  -- at the start of second word
  edit.draw(Editor_state)
  edit.run_after_keychord(Editor_state, 'M-left')
  check_eq(Editor_state.cursor1.pos, 1, 'F - test_skip_multiple_spaces_to_previous_word')
end

function test_move_to_start_of_word_on_previous_line()
  io.write('\ntest_move_to_start_of_word_on_previous_line')
  App.screen.init{width=120, height=60}
  Editor_state = edit.initialize_test_state()
  Editor_state.lines = load_array{'abc def', 'ghi'}
  Text.redraw_all(Editor_state)
  Editor_state.cursor1 = {line=2, pos=1}
  edit.draw(Editor_state)
  edit.run_after_keychord(Editor_state, 'M-left')
  check_eq(Editor_state.cursor1.line, 1, 'F - test_move_to_start_of_word_on_previous_line/line')
  check_eq(Editor_state.cursor1.pos, 5, 'F - test_move_to_start_of_word_on_previous_line/pos')
end

function test_move_past_end_of_word()
  io.write('\ntest_move_past_end_of_word')
  App.screen.init{width=120, height=60}
  Editor_state = edit.initialize_test_state()
  Editor_state.lines = load_array{'abc def'}
  Text.redraw_all(Editor_state)
  Editor_state.cursor1 = {line=1, pos=1}
  edit.draw(Editor_state)
  edit.run_after_keychord(Editor_state, 'M-right')
  check_eq(Editor_state.cursor1.pos, 4, 'F - test_move_past_end_of_word')
end

function test_skip_to_next_word()
  io.write('\ntest_skip_to_next_word')
  App.screen.init{width=120, height=60}
  Editor_state = edit.initialize_test_state()
  Editor_state.lines = load_array{'abc def'}
  Text.redraw_all(Editor_state)
  Editor_state.cursor1 = {line=1, pos=4}  -- at the space between words
  edit.draw(Editor_state)
  edit.run_after_keychord(Editor_state, 'M-right')
  check_eq(Editor_state.cursor1.pos, 8, 'F - test_skip_to_next_word')
end

function test_skip_past_tab_to_next_word()
  io.write('\ntest_skip_past_tab_to_next_word')
  App.screen.init{width=120, height=60}
  Editor_state = edit.initialize_test_state()
  Editor_state.lines = load_array{'abc\tdef'}
  Text.redraw_all(Editor_state)
  Editor_state.cursor1 = {line=1, pos=1}  -- at the space between words
  edit.draw(Editor_state)
  edit.run_after_keychord(Editor_state, 'M-right')
  check_eq(Editor_state.cursor1.pos, 4, 'F - test_skip_past_tab_to_next_word')
end

function test_skip_multiple_spaces_to_next_word()
  io.write('\ntest_skip_multiple_spaces_to_next_word')
  App.screen.init{width=120, height=60}
  Editor_state = edit.initialize_test_state()
  Editor_state.lines = load_array{'abc  def'}
  Text.redraw_all(Editor_state)
  Editor_state.cursor1 = {line=1, pos=4}  -- at the start of second word
  edit.draw(Editor_state)
  edit.run_after_keychord(Editor_state, 'M-right')
  check_eq(Editor_state.cursor1.pos, 9, 'F - test_skip_multiple_spaces_to_next_word')
end

function test_move_past_end_of_word_on_next_line()
  io.write('\ntest_move_past_end_of_word_on_next_line')
  App.screen.init{width=120, height=60}
  Editor_state = edit.initialize_test_state()
  Editor_state.lines = load_array{'abc def', 'ghi'}
  Text.redraw_all(Editor_state)
  Editor_state.cursor1 = {line=1, pos=8}
  edit.draw(Editor_state)
  edit.run_after_keychord(Editor_state, 'M-right')
  check_eq(Editor_state.cursor1.line, 2, 'F - test_move_past_end_of_word_on_next_line/line')
  check_eq(Editor_state.cursor1.pos, 4, 'F - test_move_past_end_of_word_on_next_line/pos')
end

function test_click_with_mouse()
  io.write('\ntest_click_with_mouse')
  -- display two lines with cursor on one of them
  App.screen.init{width=50, height=80}
  Editor_state = edit.initialize_test_state()
  Editor_state.lines = load_array{'abc', 'def'}
  Text.redraw_all(Editor_state)
  Editor_state.cursor1 = {line=2, pos=1}
  Editor_state.screen_top1 = {line=1, pos=1}
  Editor_state.screen_bottom1 = {}
  -- click on the other line
  edit.draw(Editor_state)
  edit.run_after_mouse_click(Editor_state, Editor_state.left+8,Editor_state.top+5, 1)
  -- cursor moves
  check_eq(Editor_state.cursor1.line, 1, 'F - test_click_with_mouse/cursor:line')
  check_nil(Editor_state.selection1.line, 'F - test_click_with_mouse/selection is empty to avoid perturbing future edits')
end

function test_click_with_mouse_to_left_of_line()
  io.write('\ntest_click_with_mouse_to_left_of_line')
  -- display a line with the cursor in the middle
  App.screen.init{width=50, height=80}
  Editor_state = edit.initialize_test_state()
  Editor_state.lines = load_array{'abc'}
  Text.redraw_all(Editor_state)
  Editor_state.cursor1 = {line=1, pos=3}
  Editor_state.screen_top1 = {line=1, pos=1}
  Editor_state.screen_bottom1 = {}
  -- click to the left of the line
  edit.draw(Editor_state)
  edit.run_after_mouse_click(Editor_state, Editor_state.left-4,Editor_state.top+5, 1)
  -- cursor moves to start of line
  check_eq(Editor_state.cursor1.line, 1, 'F - test_click_with_mouse_to_left_of_line/cursor:line')
  check_eq(Editor_state.cursor1.pos, 1, 'F - test_click_with_mouse_to_left_of_line/cursor:pos')
  check_nil(Editor_state.selection1.line, 'F - test_click_with_mouse_to_left_of_line/selection is empty to avoid perturbing future edits')
end

function test_click_with_mouse_takes_margins_into_account()
  io.write('\ntest_click_with_mouse_takes_margins_into_account')
  -- display two lines with cursor on one of them
  App.screen.init{width=100, height=80}
  Editor_state = edit.initialize_test_state()
  Editor_state.left = 50  -- occupy only right side of screen
  Editor_state.lines = load_array{'abc', 'def'}
  Text.redraw_all(Editor_state)
  Editor_state.cursor1 = {line=2, pos=1}
  Editor_state.screen_top1 = {line=1, pos=1}
  Editor_state.screen_bottom1 = {}
  -- click on the other line
  edit.draw(Editor_state)
  edit.run_after_mouse_click(Editor_state, Editor_state.left+8,Editor_state.top+5, 1)
  -- cursor moves
  check_eq(Editor_state.cursor1.line, 1, 'F - test_click_with_mouse_takes_margins_into_account/cursor:line')
  check_eq(Editor_state.cursor1.pos, 2, 'F - test_click_with_mouse_takes_margins_into_account/cursor:pos')
  check_nil(Editor_state.selection1.line, 'F - test_click_with_mouse_takes_margins_into_account/selection is empty to avoid perturbing future edits')
end

function test_click_with_mouse_on_empty_line()
  io.write('\ntest_click_with_mouse_on_empty_line')
  -- display two lines with the first one empty
  App.screen.init{width=50, height=80}
  Editor_state = edit.initialize_test_state()
  Editor_state.lines = load_array{'', 'def'}
  Text.redraw_all(Editor_state)
  Editor_state.cursor1 = {line=2, pos=1}
  Editor_state.screen_top1 = {line=1, pos=1}
  Editor_state.screen_bottom1 = {}
  -- click on the empty line
  edit.draw(Editor_state)
  edit.run_after_mouse_click(Editor_state, Editor_state.left+8,Editor_state.top+5, 1)
  -- cursor moves
  check_eq(Editor_state.cursor1.line, 1, 'F - test_click_with_mouse_on_empty_line/cursor')
end

function test_draw_text()
  io.write('\ntest_draw_text')
  App.screen.init{width=120, height=60}
  Editor_state = edit.initialize_test_state()
  Editor_state.lines = load_array{'abc', 'def', 'ghi'}
  Text.redraw_all(Editor_state)
  Editor_state.cursor1 = {line=1, pos=1}
  Editor_state.screen_top1 = {line=1, pos=1}
  Editor_state.screen_bottom1 = {}
  edit.draw(Editor_state)
  local y = Editor_state.top
  App.screen.check(y, 'abc', 'F - test_draw_text/screen:1')
  y = y + Editor_state.line_height
  App.screen.check(y, 'def', 'F - test_draw_text/screen:2')
  y = y + Editor_state.line_height
  App.screen.check(y, 'ghi', 'F - test_draw_text/screen:3')
end

function test_draw_wrapping_text()
  io.write('\ntest_draw_wrapping_text')
  App.screen.init{width=50, height=60}
  Editor_state = edit.initialize_test_state()
  Editor_state.lines = load_array{'abc', 'defgh', 'xyz'}
  Text.redraw_all(Editor_state)
  Editor_state.cursor1 = {line=1, pos=1}
  Editor_state.screen_top1 = {line=1, pos=1}
  Editor_state.screen_bottom1 = {}
  edit.draw(Editor_state)
  local y = Editor_state.top
  App.screen.check(y, 'abc', 'F - test_draw_wrapping_text/screen:1')
  y = y + Editor_state.line_height
  App.screen.check(y, 'de', 'F - test_draw_wrapping_text/screen:2')
  y = y + Editor_state.line_height
  App.screen.check(y, 'fgh', 'F - test_draw_wrapping_text/screen:3')
end

function test_draw_word_wrapping_text()
  io.write('\ntest_draw_word_wrapping_text')
  App.screen.init{width=60, height=60}
  Editor_state = edit.initialize_test_state()
  Editor_state.lines = load_array{'abc def ghi', 'jkl'}
  Text.redraw_all(Editor_state)
  Editor_state.cursor1 = {line=1, pos=1}
  Editor_state.screen_top1 = {line=1, pos=1}
  Editor_state.screen_bottom1 = {}
  edit.draw(Editor_state)
  local y = Editor_state.top
  App.screen.check(y, 'abc ', 'F - test_draw_word_wrapping_text/screen:1')
  y = y + Editor_state.line_height
  App.screen.check(y, 'def ', 'F - test_draw_word_wrapping_text/screen:2')
  y = y + Editor_state.line_height
  App.screen.check(y, 'ghi', 'F - test_draw_word_wrapping_text/screen:3')
end

function test_click_with_mouse_on_wrapping_line()
  io.write('\ntest_click_with_mouse_on_wrapping_line')
  -- display two lines with cursor on one of them
  App.screen.init{width=50, height=80}
  Editor_state = edit.initialize_test_state()
  Editor_state.lines = load_array{'abc def ghi jkl mno pqr stu'}
  Text.redraw_all(Editor_state)
  Editor_state.cursor1 = {line=1, pos=20}
  Editor_state.screen_top1 = {line=1, pos=1}
  Editor_state.screen_bottom1 = {}
  -- click on the other line
  edit.draw(Editor_state)
  edit.run_after_mouse_click(Editor_state, Editor_state.left+8,Editor_state.top+5, 1)
  -- cursor moves
  check_eq(Editor_state.cursor1.line, 1, 'F - test_click_with_mouse_on_wrapping_line/cursor:line')
  check_eq(Editor_state.cursor1.pos, 2, 'F - test_click_with_mouse_on_wrapping_line/cursor:pos')
  check_nil(Editor_state.selection1.line, 'F - test_click_with_mouse_on_wrapping_line/selection is empty to avoid perturbing future edits')
end

function test_click_with_mouse_on_wrapping_line_takes_margins_into_account()
  io.write('\ntest_click_with_mouse_on_wrapping_line_takes_margins_into_account')
  -- display two lines with cursor on one of them
  App.screen.init{width=100, height=80}
  Editor_state = edit.initialize_test_state()
  Editor_state.left = 50  -- occupy only right side of screen
  Editor_state.lines = load_array{'abc def ghi jkl mno pqr stu'}
  Text.redraw_all(Editor_state)
  Editor_state.cursor1 = {line=1, pos=20}
  Editor_state.screen_top1 = {line=1, pos=1}
  Editor_state.screen_bottom1 = {}
  -- click on the other line
  edit.draw(Editor_state)
  edit.run_after_mouse_click(Editor_state, Editor_state.left+8,Editor_state.top+5, 1)
  -- cursor moves
  check_eq(Editor_state.cursor1.line, 1, 'F - test_click_with_mouse_on_wrapping_line_takes_margins_into_account/cursor:line')
  check_eq(Editor_state.cursor1.pos, 2, 'F - test_click_with_mouse_on_wrapping_line_takes_margins_into_account/cursor:pos')
  check_nil(Editor_state.selection1.line, 'F - test_click_with_mouse_on_wrapping_line_takes_margins_into_account/selection is empty to avoid perturbing future edits')
end

function test_draw_text_wrapping_within_word()
  -- arrange a screen line that needs to be split within a word
  io.write('\ntest_draw_text_wrapping_within_word')
  App.screen.init{width=60, height=60}
  Editor_state = edit.initialize_test_state()
  Editor_state.lines = load_array{'abcd e fghijk', 'xyz'}
  Text.redraw_all(Editor_state)
  Editor_state.cursor1 = {line=1, pos=1}
  Editor_state.screen_top1 = {line=1, pos=1}
  Editor_state.screen_bottom1 = {}
  edit.draw(Editor_state)
  local y = Editor_state.top
  App.screen.check(y, 'abcd ', 'F - test_draw_text_wrapping_within_word/screen:1')
  y = y + Editor_state.line_height
  App.screen.check(y, 'e fgh', 'F - test_draw_text_wrapping_within_word/screen:2')
  y = y + Editor_state.line_height
  App.screen.check(y, 'ijk', 'F - test_draw_text_wrapping_within_word/screen:3')
end

function test_draw_wrapping_text_containing_non_ascii()
  -- draw a long line containing non-ASCII
  io.write('\ntest_draw_wrapping_text_containing_non_ascii')
  App.screen.init{width=60, height=60}
  Editor_state = edit.initialize_test_state()
  Editor_state.lines = load_array{'madam I’m adam', 'xyz'}  -- notice the non-ASCII apostrophe
  Text.redraw_all(Editor_state)
  Editor_state.cursor1 = {line=1, pos=1}
  Editor_state.screen_top1 = {line=1, pos=1}
  Editor_state.screen_bottom1 = {}
  edit.draw(Editor_state)
  local y = Editor_state.top
  App.screen.check(y, 'mad', 'F - test_draw_wrapping_text_containing_non_ascii/screen:1')
  y = y + Editor_state.line_height
  App.screen.check(y, 'am I', 'F - test_draw_wrapping_text_containing_non_ascii/screen:2')
  y = y + Editor_state.line_height
  App.screen.check(y, '’m a', 'F - test_draw_wrapping_text_containing_non_ascii/screen:3')
end

function test_click_on_wrapping_line()
  io.write('\ntest_click_on_wrapping_line')
  -- display a wrapping line
  App.screen.init{width=75, height=80}
  Editor_state = edit.initialize_test_state()
                               --  12345678901234
  Editor_state.lines = load_array{"madam I'm adam"}
  Text.redraw_all(Editor_state)
  Editor_state.cursor1 = {line=1, pos=1}
  Editor_state.screen_top1 = {line=1, pos=1}
  Editor_state.screen_bottom1 = {}
  edit.draw(Editor_state)
  local y = Editor_state.top
  App.screen.check(y, 'madam ', 'F - test_click_on_wrapping_line/baseline/screen:1')
  y = y + Editor_state.line_height
  App.screen.check(y, "I'm ad", 'F - test_click_on_wrapping_line/baseline/screen:2')
  y = y + Editor_state.line_height
  -- click past end of second screen line
  edit.run_after_mouse_click(Editor_state, App.screen.width-2,y-2, 1)
  -- cursor moves to end of screen line
  check_eq(Editor_state.cursor1.line, 1, 'F - test_click_on_wrapping_line/cursor:line')
  check_eq(Editor_state.cursor1.pos, 12, 'F - test_click_on_wrapping_line/cursor:pos')
end

function test_click_on_wrapping_line_rendered_from_partway_at_top_of_screen()
  io.write('\ntest_click_on_wrapping_line_rendered_from_partway_at_top_of_screen')
  -- display a wrapping line from its second screen line
  App.screen.init{width=75, height=80}
  Editor_state = edit.initialize_test_state()
                               --  12345678901234
  Editor_state.lines = load_array{"madam I'm adam"}
  Text.redraw_all(Editor_state)
  Editor_state.cursor1 = {line=1, pos=8}
  Editor_state.screen_top1 = {line=1, pos=7}
  Editor_state.screen_bottom1 = {}
  edit.draw(Editor_state)
  local y = Editor_state.top
  App.screen.check(y, "I'm ad", 'F - test_click_on_wrapping_line_rendered_from_partway_at_top_of_screen/baseline/screen:2')
  y = y + Editor_state.line_height
  -- click past end of second screen line
  edit.run_after_mouse_click(Editor_state, App.screen.width-2,y-2, 1)
  -- cursor moves to end of screen line
  check_eq(Editor_state.cursor1.line, 1, 'F - test_click_on_wrapping_line_rendered_from_partway_at_top_of_screen/cursor:line')
  check_eq(Editor_state.cursor1.pos, 12, 'F - test_click_on_wrapping_line_rendered_from_partway_at_top_of_screen/cursor:pos')
end

function test_click_past_end_of_wrapping_line()
  io.write('\ntest_click_past_end_of_wrapping_line')
  -- display a wrapping line
  App.screen.init{width=75, height=80}
  Editor_state = edit.initialize_test_state()
                               --  12345678901234
  Editor_state.lines = load_array{"madam I'm adam"}
  Text.redraw_all(Editor_state)
  Editor_state.cursor1 = {line=1, pos=1}
  Editor_state.screen_top1 = {line=1, pos=1}
  Editor_state.screen_bottom1 = {}
  edit.draw(Editor_state)
  local y = Editor_state.top
  App.screen.check(y, 'madam ', 'F - test_click_past_end_of_wrapping_line/baseline/screen:1')
  y = y + Editor_state.line_height
  App.screen.check(y, "I'm ad", 'F - test_click_past_end_of_wrapping_line/baseline/screen:2')
  y = y + Editor_state.line_height
  App.screen.check(y, 'am', 'F - test_click_past_end_of_wrapping_line/baseline/screen:3')
  y = y + Editor_state.line_height
  -- click past the end of it
  edit.run_after_mouse_click(Editor_state, App.screen.width-2,y-2, 1)
  -- cursor moves to end of line
  check_eq(Editor_state.cursor1.pos, 15, 'F - test_click_past_end_of_wrapping_line/cursor')  -- one more than the number of UTF-8 code-points
end

function test_click_past_end_of_wrapping_line_containing_non_ascii()
  io.write('\ntest_click_past_end_of_wrapping_line_containing_non_ascii')
  -- display a wrapping line containing non-ASCII
  App.screen.init{width=75, height=80}
  Editor_state = edit.initialize_test_state()
                               --  12345678901234
  Editor_state.lines = load_array{'madam I’m adam'}  -- notice the non-ASCII apostrophe
  Text.redraw_all(Editor_state)
  Editor_state.cursor1 = {line=1, pos=1}
  Editor_state.screen_top1 = {line=1, pos=1}
  Editor_state.screen_bottom1 = {}
  edit.draw(Editor_state)
  local y = Editor_state.top
  App.screen.check(y, 'madam ', 'F - test_click_past_end_of_wrapping_line_containing_non_ascii/baseline/screen:1')
  y = y + Editor_state.line_height
  App.screen.check(y, 'I’m ad', 'F - test_click_past_end_of_wrapping_line_containing_non_ascii/baseline/screen:2')
  y = y + Editor_state.line_height
  App.screen.check(y, 'am', 'F - test_click_past_end_of_wrapping_line_containing_non_ascii/baseline/screen:3')
  y = y + Editor_state.line_height
  -- click past the end of it
  edit.run_after_mouse_click(Editor_state, App.screen.width-2,y-2, 1)
  -- cursor moves to end of line
  check_eq(Editor_state.cursor1.pos, 15, 'F - test_click_past_end_of_wrapping_line_containing_non_ascii/cursor')  -- one more than the number of UTF-8 code-points
end

function test_click_past_end_of_word_wrapping_line()
  io.write('\ntest_click_past_end_of_word_wrapping_line')
  -- display a long line wrapping at a word boundary on a screen of more realistic length
  App.screen.init{width=160, height=80}
  Editor_state = edit.initialize_test_state()
                                -- 0        1         2
                                -- 123456789012345678901
  Editor_state.lines = load_array{'the quick brown fox jumped over the lazy dog'}
  Text.redraw_all(Editor_state)
  Editor_state.cursor1 = {line=1, pos=1}
  Editor_state.screen_top1 = {line=1, pos=1}
  Editor_state.screen_bottom1 = {}
  edit.draw(Editor_state)
  local y = Editor_state.top
  App.screen.check(y, 'the quick brown fox ', 'F - test_click_past_end_of_word_wrapping_line/baseline/screen:1')
  y = y + Editor_state.line_height
  -- click past the end of the screen line
  edit.run_after_mouse_click(Editor_state, App.screen.width-2,y-2, 1)
  -- cursor moves to end of screen line
  check_eq(Editor_state.cursor1.pos, 20, 'F - test_click_past_end_of_word_wrapping_line/cursor')
end

function test_select_text()
  io.write('\ntest_select_text')
  -- display a line of text
  App.screen.init{width=75, height=80}
  Editor_state = edit.initialize_test_state()
  Editor_state.lines = load_array{'abc def'}
  Text.redraw_all(Editor_state)
  Editor_state.cursor1 = {line=1, pos=1}
  Editor_state.screen_top1 = {line=1, pos=1}
  Editor_state.screen_bottom1 = {}
  edit.draw(Editor_state)
  -- select a letter
  App.fake_key_press('lshift')
  edit.run_after_keychord(Editor_state, 'S-right')
  App.fake_key_release('lshift')
  edit.key_released(Editor_state, 'lshift')
  -- selection persists even after shift is released
  check_eq(Editor_state.selection1.line, 1, 'F - test_select_text/selection:line')
  check_eq(Editor_state.selection1.pos, 1, 'F - test_select_text/selection:pos')
  check_eq(Editor_state.cursor1.line, 1, 'F - test_select_text/cursor:line')
  check_eq(Editor_state.cursor1.pos, 2, 'F - test_select_text/cursor:pos')
end

function test_cursor_movement_without_shift_resets_selection()
  io.write('\ntest_cursor_movement_without_shift_resets_selection')
  -- display a line of text with some part selected
  App.screen.init{width=75, height=80}
  Editor_state = edit.initialize_test_state()
  Editor_state.lines = load_array{'abc'}
  Text.redraw_all(Editor_state)
  Editor_state.cursor1 = {line=1, pos=1}
  Editor_state.selection1 = {line=1, pos=2}
  Editor_state.screen_top1 = {line=1, pos=1}
  Editor_state.screen_bottom1 = {}
  edit.draw(Editor_state)
  -- press an arrow key without shift
  edit.run_after_keychord(Editor_state, 'right')
  -- no change to data, selection is reset
  check_nil(Editor_state.selection1.line, 'F - test_cursor_movement_without_shift_resets_selection')
  check_eq(Editor_state.lines[1].data, 'abc', 'F - test_cursor_movement_without_shift_resets_selection/data')
end

function test_edit_deletes_selection()
  io.write('\ntest_edit_deletes_selection')
  -- display a line of text with some part selected
  App.screen.init{width=75, height=80}
  Editor_state = edit.initialize_test_state()
  Editor_state.lines = load_array{'abc'}
  Text.redraw_all(Editor_state)
  Editor_state.cursor1 = {line=1, pos=1}
  Editor_state.selection1 = {line=1, pos=2}
  Editor_state.screen_top1 = {line=1, pos=1}
  Editor_state.screen_bottom1 = {}
  edit.draw(Editor_state)
  -- press a key
  edit.run_after_textinput(Editor_state, 'x')
  -- selected text is deleted and replaced with the key
  check_eq(Editor_state.lines[1].data, 'xbc', 'F - test_edit_deletes_selection')
end

function test_edit_with_shift_key_deletes_selection()
  io.write('\ntest_edit_with_shift_key_deletes_selection')
  -- display a line of text with some part selected
  App.screen.init{width=75, height=80}
  Editor_state = edit.initialize_test_state()
  Editor_state.lines = load_array{'abc'}
  Text.redraw_all(Editor_state)
  Editor_state.cursor1 = {line=1, pos=1}
  Editor_state.selection1 = {line=1, pos=2}
  Editor_state.screen_top1 = {line=1, pos=1}
  Editor_state.screen_bottom1 = {}
  edit.draw(Editor_state)
  -- mimic precise keypresses for a capital letter
  App.fake_key_press('lshift')
  edit.keychord_pressed(Editor_state, 'd', 'd')
  edit.textinput(Editor_state, 'D')
  edit.key_released(Editor_state, 'd')
  App.fake_key_release('lshift')
  -- selected text is deleted and replaced with the key
  check_nil(Editor_state.selection1.line, 'F - test_edit_with_shift_key_deletes_selection')
  check_eq(Editor_state.lines[1].data, 'Dbc', 'F - test_edit_with_shift_key_deletes_selection/data')
end

function test_copy_does_not_reset_selection()
  io.write('\ntest_copy_does_not_reset_selection')
  -- display a line of text with a selection
  App.screen.init{width=75, height=80}
  Editor_state = edit.initialize_test_state()
  Editor_state.lines = load_array{'abc'}
  Text.redraw_all(Editor_state)
  Editor_state.cursor1 = {line=1, pos=1}
  Editor_state.selection1 = {line=1, pos=2}
  Editor_state.screen_top1 = {line=1, pos=1}
  Editor_state.screen_bottom1 = {}
  edit.draw(Editor_state)
  -- copy selection
  edit.run_after_keychord(Editor_state, 'C-c')
  check_eq(App.clipboard, 'a', 'F - test_copy_does_not_reset_selection/clipboard')
  -- selection is reset since shift key is not pressed
  check(Editor_state.selection1.line, 'F - test_copy_does_not_reset_selection')
end

function test_cut()
  io.write('\ntest_cut')
  -- display a line of text with some part selected
  App.screen.init{width=75, height=80}
  Editor_state = edit.initialize_test_state()
  Editor_state.lines = load_array{'abc'}
  Text.redraw_all(Editor_state)
  Editor_state.cursor1 = {line=1, pos=1}
  Editor_state.selection1 = {line=1, pos=2}
  Editor_state.screen_top1 = {line=1, pos=1}
  Editor_state.screen_bottom1 = {}
  edit.draw(Editor_state)
  -- press a key
  edit.run_after_keychord(Editor_state, 'C-x')
  check_eq(App.clipboard, 'a', 'F - test_cut/clipboard')
  -- selected text is deleted
  check_eq(Editor_state.lines[1].data, 'bc', 'F - test_cut/data')
end

function test_paste_replaces_selection()
  io.write('\ntest_paste_replaces_selection')
  -- display a line of text with a selection
  App.screen.init{width=75, height=80}
  Editor_state = edit.initialize_test_state()
  Editor_state.lines = load_array{'abc', 'def'}
  Text.redraw_all(Editor_state)
  Editor_state.cursor1 = {line=2, pos=1}
  Editor_state.selection1 = {line=1, pos=1}
  Editor_state.screen_top1 = {line=1, pos=1}
  Editor_state.screen_bottom1 = {}
  edit.draw(Editor_state)
  -- set clipboard
  App.clipboard = 'xyz'
  -- paste selection
  edit.run_after_keychord(Editor_state, 'C-v')
  -- selection is reset since shift key is not pressed
  -- selection includes the newline, so it's also deleted
  check_eq(Editor_state.lines[1].data, 'xyzdef', 'F - test_paste_replaces_selection')
end

function test_deleting_selection_may_scroll()
  io.write('\ntest_deleting_selection_may_scroll')
  -- display lines 2/3/4
  App.screen.init{width=120, height=60}
  Editor_state = edit.initialize_test_state()
  Editor_state.lines = load_array{'abc', 'def', 'ghi', 'jkl'}
  Text.redraw_all(Editor_state)
  Editor_state.cursor1 = {line=3, pos=2}
  Editor_state.screen_top1 = {line=2, pos=1}
  Editor_state.screen_bottom1 = {}
  edit.draw(Editor_state)
  local y = Editor_state.top
  App.screen.check(y, 'def', 'F - test_deleting_selection_may_scroll/baseline/screen:1')
  y = y + Editor_state.line_height
  App.screen.check(y, 'ghi', 'F - test_deleting_selection_may_scroll/baseline/screen:2')
  y = y + Editor_state.line_height
  App.screen.check(y, 'jkl', 'F - test_deleting_selection_may_scroll/baseline/screen:3')
  -- set up a selection starting above the currently displayed page
  Editor_state.selection1 = {line=1, pos=2}
  -- delete selection
  edit.run_after_keychord(Editor_state, 'backspace')
  -- page scrolls up
  check_eq(Editor_state.screen_top1.line, 1, 'F - test_deleting_selection_may_scroll')
  check_eq(Editor_state.lines[1].data, 'ahi', 'F - test_deleting_selection_may_scroll/data')
end

function test_edit_wrapping_text()
  io.write('\ntest_edit_wrapping_text')
  App.screen.init{width=50, height=60}
  Editor_state = edit.initialize_test_state()
  Editor_state.lines = load_array{'abc', 'def', 'xyz'}
  Text.redraw_all(Editor_state)
  Editor_state.cursor1 = {line=2, pos=4}
  Editor_state.screen_top1 = {line=1, pos=1}
  Editor_state.screen_bottom1 = {}
  edit.draw(Editor_state)
  edit.run_after_textinput(Editor_state, 'g')
  local y = Editor_state.top
  App.screen.check(y, 'abc', 'F - test_edit_wrapping_text/screen:1')
  y = y + Editor_state.line_height
  App.screen.check(y, 'de', 'F - test_edit_wrapping_text/screen:2')
  y = y + Editor_state.line_height
  App.screen.check(y, 'fg', 'F - test_edit_wrapping_text/screen:3')
end

function test_insert_newline()
  io.write('\ntest_insert_newline')
  -- display a few lines
  App.screen.init{width=Editor_state.left+30, height=60}
  Editor_state = edit.initialize_test_state()
  Editor_state.lines = load_array{'abc', 'def', 'ghi', 'jkl'}
  Text.redraw_all(Editor_state)
  Editor_state.cursor1 = {line=1, pos=2}
  Editor_state.screen_top1 = {line=1, pos=1}
  Editor_state.screen_bottom1 = {}
  edit.draw(Editor_state)
  local y = Editor_state.top
  App.screen.check(y, 'abc', 'F - test_insert_newline/baseline/screen:1')
  y = y + Editor_state.line_height
  App.screen.check(y, 'def', 'F - test_insert_newline/baseline/screen:2')
  y = y + Editor_state.line_height
  App.screen.check(y, 'ghi', 'F - test_insert_newline/baseline/screen:3')
  -- hitting the enter key splits the line
  edit.run_after_keychord(Editor_state, 'return')
  check_eq(Editor_state.screen_top1.line, 1, 'F - test_insert_newline/screen_top')
  check_eq(Editor_state.cursor1.line, 2, 'F - test_insert_newline/cursor:line')
  check_eq(Editor_state.cursor1.pos, 1, 'F - test_insert_newline/cursor:pos')
  y = Editor_state.top
  App.screen.check(y, 'a', 'F - test_insert_newline/screen:1')
  y = y + Editor_state.line_height
  App.screen.check(y, 'bc', 'F - test_insert_newline/screen:2')
  y = y + Editor_state.line_height
  App.screen.check(y, 'def', 'F - test_insert_newline/screen:3')
end

function test_insert_newline_at_start_of_line()
  io.write('\ntest_insert_newline_at_start_of_line')
  -- display a line
  App.screen.init{width=Editor_state.left+30, height=60}
  Editor_state = edit.initialize_test_state()
  Editor_state.lines = load_array{'abc'}
  Text.redraw_all(Editor_state)
  Editor_state.cursor1 = {line=1, pos=1}
  Editor_state.screen_top1 = {line=1, pos=1}
  Editor_state.screen_bottom1 = {}
  -- hitting the enter key splits the line
  edit.run_after_keychord(Editor_state, 'return')
  check_eq(Editor_state.cursor1.line, 2, 'F - test_insert_newline_at_start_of_line/cursor:line')
  check_eq(Editor_state.cursor1.pos, 1, 'F - test_insert_newline_at_start_of_line/cursor:pos')
  check_eq(Editor_state.lines[1].data, '', 'F - test_insert_newline_at_start_of_line/data:1')
  check_eq(Editor_state.lines[2].data, 'abc', 'F - test_insert_newline_at_start_of_line/data:2')
end

function test_insert_from_clipboard()
  io.write('\ntest_insert_from_clipboard')
  -- display a few lines
  App.screen.init{width=Editor_state.left+30, height=60}
  Editor_state = edit.initialize_test_state()
  Editor_state.lines = load_array{'abc', 'def', 'ghi', 'jkl'}
  Text.redraw_all(Editor_state)
  Editor_state.cursor1 = {line=1, pos=2}
  Editor_state.screen_top1 = {line=1, pos=1}
  Editor_state.screen_bottom1 = {}
  edit.draw(Editor_state)
  local y = Editor_state.top
  App.screen.check(y, 'abc', 'F - test_insert_from_clipboard/baseline/screen:1')
  y = y + Editor_state.line_height
  App.screen.check(y, 'def', 'F - test_insert_from_clipboard/baseline/screen:2')
  y = y + Editor_state.line_height
  App.screen.check(y, 'ghi', 'F - test_insert_from_clipboard/baseline/screen:3')
  -- paste some text including a newline, check that new line is created
  App.clipboard = 'xy\nz'
  edit.run_after_keychord(Editor_state, 'C-v')
  check_eq(Editor_state.screen_top1.line, 1, 'F - test_insert_from_clipboard/screen_top')
  check_eq(Editor_state.cursor1.line, 2, 'F - test_insert_from_clipboard/cursor:line')
  check_eq(Editor_state.cursor1.pos, 2, 'F - test_insert_from_clipboard/cursor:pos')
  y = Editor_state.top
  App.screen.check(y, 'axy', 'F - test_insert_from_clipboard/screen:1')
  y = y + Editor_state.line_height
  App.screen.check(y, 'zbc', 'F - test_insert_from_clipboard/screen:2')
  y = y + Editor_state.line_height
  App.screen.check(y, 'def', 'F - test_insert_from_clipboard/screen:3')
end

function test_move_cursor_using_mouse()
  io.write('\ntest_move_cursor_using_mouse')
  App.screen.init{width=50, height=60}
  Editor_state = edit.initialize_test_state()
  Editor_state.lines = load_array{'abc', 'def', 'xyz'}
  Text.redraw_all(Editor_state)
  Editor_state.cursor1 = {line=1, pos=1}
  Editor_state.screen_top1 = {line=1, pos=1}
  Editor_state.screen_bottom1 = {}
  Editor_state.selection1 = {}
  edit.draw(Editor_state)  -- populate line_cache.starty for each line Editor_state.line_cache
  edit.run_after_mouse_release(Editor_state, Editor_state.left+8,Editor_state.top+5, 1)
  check_eq(Editor_state.cursor1.line, 1, 'F - test_move_cursor_using_mouse/cursor:line')
  check_eq(Editor_state.cursor1.pos, 2, 'F - test_move_cursor_using_mouse/cursor:pos')
  check_nil(Editor_state.selection1.line, 'F - test_move_cursor_using_mouse/selection:line')
  check_nil(Editor_state.selection1.pos, 'F - test_move_cursor_using_mouse/selection:pos')
end

function test_select_text_using_mouse()
  io.write('\ntest_select_text_using_mouse')
  App.screen.init{width=50, height=60}
  Editor_state = edit.initialize_test_state()
  Editor_state.lines = load_array{'abc', 'def', 'xyz'}
  Text.redraw_all(Editor_state)
  Editor_state.cursor1 = {line=1, pos=1}
  Editor_state.screen_top1 = {line=1, pos=1}
  Editor_state.screen_bottom1 = {}
  Editor_state.selection1 = {}
  edit.draw(Editor_state)  -- populate line_cache.starty for each line Editor_state.line_cache
  -- press and hold on first location
  edit.run_after_mouse_press(Editor_state, Editor_state.left+8,Editor_state.top+5, 1)
  -- drag and release somewhere else
  edit.run_after_mouse_release(Editor_state, Editor_state.left+20,Editor_state.top+Editor_state.line_height+5, 1)
  check_eq(Editor_state.selection1.line, 1, 'F - test_select_text_using_mouse/selection:line')
  check_eq(Editor_state.selection1.pos, 2, 'F - test_select_text_using_mouse/selection:pos')
  check_eq(Editor_state.cursor1.line, 2, 'F - test_select_text_using_mouse/cursor:line')
  check_eq(Editor_state.cursor1.pos, 4, 'F - test_select_text_using_mouse/cursor:pos')
end

function test_select_text_using_mouse_and_shift()
  io.write('\ntest_select_text_using_mouse_and_shift')
  App.screen.init{width=50, height=60}
  Editor_state = edit.initialize_test_state()
  Editor_state.lines = load_array{'abc', 'def', 'xyz'}
  Text.redraw_all(Editor_state)
  Editor_state.cursor1 = {line=1, pos=1}
  Editor_state.screen_top1 = {line=1, pos=1}
  Editor_state.screen_bottom1 = {}
  Editor_state.selection1 = {}
  edit.draw(Editor_state)  -- populate line_cache.starty for each line Editor_state.line_cache
  -- click on first location
  edit.run_after_mouse_press(Editor_state, Editor_state.left+8,Editor_state.top+5, 1)
  edit.run_after_mouse_release(Editor_state, Editor_state.left+8,Editor_state.top+5, 1)
  -- hold down shift and click somewhere else
  App.fake_key_press('lshift')
  edit.run_after_mouse_press(Editor_state, Editor_state.left+20,Editor_state.top+5, 1)
  edit.run_after_mouse_release(Editor_state, Editor_state.left+20,Editor_state.top+Editor_state.line_height+5, 1)
  App.fake_key_release('lshift')
  check_eq(Editor_state.selection1.line, 1, 'F - test_select_text_using_mouse_and_shift/selection:line')
  check_eq(Editor_state.selection1.pos, 2, 'F - test_select_text_using_mouse_and_shift/selection:pos')
  check_eq(Editor_state.cursor1.line, 2, 'F - test_select_text_using_mouse_and_shift/cursor:line')
  check_eq(Editor_state.cursor1.pos, 4, 'F - test_select_text_using_mouse_and_shift/cursor:pos')
end

function test_select_text_repeatedly_using_mouse_and_shift()
  io.write('\ntest_select_text_repeatedly_using_mouse_and_shift')
  App.screen.init{width=50, height=60}
  Editor_state = edit.initialize_test_state()
  Editor_state.lines = load_array{'abc', 'def', 'xyz'}
  Text.redraw_all(Editor_state)
  Text.redraw_all(Editor_state)
  Editor_state.cursor1 = {line=1, pos=1}
  Editor_state.screen_top1 = {line=1, pos=1}
  Editor_state.screen_bottom1 = {}
  Editor_state.selection1 = {}
  edit.draw(Editor_state)  -- populate line_cache.starty for each line Editor_state.line_cache
  -- click on first location
  edit.run_after_mouse_press(Editor_state, Editor_state.left+8,Editor_state.top+5, 1)
  edit.run_after_mouse_release(Editor_state, Editor_state.left+8,Editor_state.top+5, 1)
  -- hold down shift and click on a second location
  App.fake_key_press('lshift')
  edit.run_after_mouse_press(Editor_state, Editor_state.left+20,Editor_state.top+5, 1)
  edit.run_after_mouse_release(Editor_state, Editor_state.left+20,Editor_state.top+Editor_state.line_height+5, 1)
  -- hold down shift and click at a third location
  App.fake_key_press('lshift')
  edit.run_after_mouse_press(Editor_state, Editor_state.left+20,Editor_state.top+5, 1)
  edit.run_after_mouse_release(Editor_state, Editor_state.left+8,Editor_state.top+Editor_state.line_height+5, 1)
  App.fake_key_release('lshift')
  -- selection is between first and third location. forget the second location, not the first.
  check_eq(Editor_state.selection1.line, 1, 'F - test_select_text_repeatedly_using_mouse_and_shift/selection:line')
  check_eq(Editor_state.selection1.pos, 2, 'F - test_select_text_repeatedly_using_mouse_and_shift/selection:pos')
  check_eq(Editor_state.cursor1.line, 2, 'F - test_select_text_repeatedly_using_mouse_and_shift/cursor:line')
  check_eq(Editor_state.cursor1.pos, 2, 'F - test_select_text_repeatedly_using_mouse_and_shift/cursor:pos')
end

function test_cut_without_selection()
  io.write('\ntest_cut_without_selection')
  -- display a few lines
  App.screen.init{width=Editor_state.left+30, height=60}
  Editor_state = edit.initialize_test_state()
  Editor_state.lines = load_array{'abc', 'def', 'ghi', 'jkl'}
  Text.redraw_all(Editor_state)
  Editor_state.cursor1 = {line=1, pos=2}
  Editor_state.screen_top1 = {line=1, pos=1}
  Editor_state.screen_bottom1 = {}
  Editor_state.selection1 = {}
  edit.draw(Editor_state)
  -- try to cut without selecting text
  edit.run_after_keychord(Editor_state, 'C-x')
  -- no crash
  check_nil(Editor_state.selection1.line, 'F - test_cut_without_selection')
end

function test_pagedown()
  io.write('\ntest_pagedown')
  App.screen.init{width=120, height=45}
  Editor_state = edit.initialize_test_state()
  Editor_state.lines = load_array{'abc', 'def', 'ghi'}
  Text.redraw_all(Editor_state)
  Editor_state.cursor1 = {line=1, pos=1}
  Editor_state.screen_top1 = {line=1, pos=1}
  Editor_state.screen_bottom1 = {}
  -- initially the first two lines are displayed
  edit.draw(Editor_state)
  local y = Editor_state.top
  App.screen.check(y, 'abc', 'F - test_pagedown/baseline/screen:1')
  y = y + Editor_state.line_height
  App.screen.check(y, 'def', 'F - test_pagedown/baseline/screen:2')
  -- after pagedown the bottom line becomes the top
  edit.run_after_keychord(Editor_state, 'pagedown')
  check_eq(Editor_state.screen_top1.line, 2, 'F - test_pagedown/screen_top')
  check_eq(Editor_state.cursor1.line, 2, 'F - test_pagedown/cursor')
  y = Editor_state.top
  App.screen.check(y, 'def', 'F - test_pagedown/screen:1')
  y = y + Editor_state.line_height
  App.screen.check(y, 'ghi', 'F - test_pagedown/screen:2')
end

function test_pagedown_often_shows_start_of_wrapping_line()
  io.write('\ntest_pagedown_often_shows_start_of_wrapping_line')
  -- draw a few lines ending in part of a wrapping line
  App.screen.init{width=50, height=60}
  Editor_state = edit.initialize_test_state()
  Editor_state.lines = load_array{'abc', 'def ghi jkl', 'mno'}
  Text.redraw_all(Editor_state)
  Editor_state.cursor1 = {line=1, pos=1}
  Editor_state.screen_top1 = {line=1, pos=1}
  Editor_state.screen_bottom1 = {}
  edit.draw(Editor_state)
  local y = Editor_state.top
  App.screen.check(y, 'abc', 'F - test_pagedown_often_shows_start_of_wrapping_line/baseline/screen:1')
  y = y + Editor_state.line_height
  App.screen.check(y, 'def ', 'F - test_pagedown_often_shows_start_of_wrapping_line/baseline/screen:2')
  y = y + Editor_state.line_height
  App.screen.check(y, 'ghi ', 'F - test_pagedown_often_shows_start_of_wrapping_line/baseline/screen:3')
  -- after pagedown we start drawing from the bottom _line_ (multiple screen lines)
  edit.run_after_keychord(Editor_state, 'pagedown')
  check_eq(Editor_state.screen_top1.line, 2, 'F - test_pagedown_often_shows_start_of_wrapping_line/screen_top:line')
  check_eq(Editor_state.screen_top1.pos, 1, 'F - test_pagedown_often_shows_start_of_wrapping_line/screen_top:pos')
  check_eq(Editor_state.cursor1.line, 2, 'F - test_pagedown_often_shows_start_of_wrapping_line/cursor:line')
  check_eq(Editor_state.cursor1.pos, 1, 'F - test_pagedown_often_shows_start_of_wrapping_line/cursor:pos')
  y = Editor_state.top
  App.screen.check(y, 'def ', 'F - test_pagedown_often_shows_start_of_wrapping_line/screen:1')
  y = y + Editor_state.line_height
  App.screen.check(y, 'ghi ', 'F - test_pagedown_often_shows_start_of_wrapping_line/screen:2')
  y = y + Editor_state.line_height
  App.screen.check(y, 'jkl', 'F - test_pagedown_often_shows_start_of_wrapping_line/screen:3')
end

function test_pagedown_can_start_from_middle_of_long_wrapping_line()
  io.write('\ntest_pagedown_can_start_from_middle_of_long_wrapping_line')
  -- draw a few lines starting from a very long wrapping line
  App.screen.init{width=Editor_state.left+30, height=60}
  Editor_state = edit.initialize_test_state()
  Editor_state.lines = load_array{'abc def ghi jkl mno pqr stu vwx yza bcd efg hij', 'XYZ'}
  Text.redraw_all(Editor_state)
  Editor_state.cursor1 = {line=1, pos=2}
  Editor_state.screen_top1 = {line=1, pos=1}
  Editor_state.screen_bottom1 = {}
  edit.draw(Editor_state)
  local y = Editor_state.top
  App.screen.check(y, 'abc ', 'F - test_pagedown_can_start_from_middle_of_long_wrapping_line/baseline/screen:1')
  y = y + Editor_state.line_height
  App.screen.check(y, 'def ', 'F - test_pagedown_can_start_from_middle_of_long_wrapping_line/baseline/screen:2')
  y = y + Editor_state.line_height
  App.screen.check(y, 'ghi ', 'F - test_pagedown_can_start_from_middle_of_long_wrapping_line/baseline/screen:3')
  -- after pagedown we scroll down the very long wrapping line
  edit.run_after_keychord(Editor_state, 'pagedown')
  check_eq(Editor_state.screen_top1.line, 1, 'F - test_pagedown_can_start_from_middle_of_long_wrapping_line/screen_top:line')
  check_eq(Editor_state.screen_top1.pos, 9, 'F - test_pagedown_can_start_from_middle_of_long_wrapping_line/screen_top:pos')
  y = Editor_state.top
  App.screen.check(y, 'ghi ', 'F - test_pagedown_can_start_from_middle_of_long_wrapping_line/screen:1')
  y = y + Editor_state.line_height
  App.screen.check(y, 'jkl ', 'F - test_pagedown_can_start_from_middle_of_long_wrapping_line/screen:2')
  y = y + Editor_state.line_height
  App.screen.check(y, 'mno ', 'F - test_pagedown_can_start_from_middle_of_long_wrapping_line/screen:3')
end

function test_pagedown_never_moves_up()
  io.write('\ntest_pagedown_never_moves_up')
  -- draw the final screen line of a wrapping line
  App.screen.init{width=Editor_state.left+30, height=60}
  Editor_state = edit.initialize_test_state()
  Editor_state.lines = load_array{'abc def ghi'}
  Text.redraw_all(Editor_state)
  Editor_state.cursor1 = {line=1, pos=9}
  Editor_state.screen_top1 = {line=1, pos=9}
  Editor_state.screen_bottom1 = {}
  edit.draw(Editor_state)
  -- pagedown makes no change
  edit.run_after_keychord(Editor_state, 'pagedown')
  check_eq(Editor_state.screen_top1.line, 1, 'F - test_pagedown_never_moves_up/screen_top:line')
  check_eq(Editor_state.screen_top1.pos, 9, 'F - test_pagedown_never_moves_up/screen_top:pos')
end

function test_down_arrow_moves_cursor()
  io.write('\ntest_down_arrow_moves_cursor')
  App.screen.init{width=120, height=60}
  Editor_state = edit.initialize_test_state()
  Editor_state.lines = load_array{'abc', 'def', 'ghi', 'jkl'}
  Text.redraw_all(Editor_state)
  Editor_state.cursor1 = {line=1, pos=1}
  Editor_state.screen_top1 = {line=1, pos=1}
  Editor_state.screen_bottom1 = {}
  -- initially the first three lines are displayed
  edit.draw(Editor_state)
  local y = Editor_state.top
  App.screen.check(y, 'abc', 'F - test_down_arrow_moves_cursor/baseline/screen:1')
  y = y + Editor_state.line_height
  App.screen.check(y, 'def', 'F - test_down_arrow_moves_cursor/baseline/screen:2')
  y = y + Editor_state.line_height
  App.screen.check(y, 'ghi', 'F - test_down_arrow_moves_cursor/baseline/screen:3')
  -- after hitting the down arrow, the cursor moves down by 1 line
  edit.run_after_keychord(Editor_state, 'down')
  check_eq(Editor_state.screen_top1.line, 1, 'F - test_down_arrow_moves_cursor/screen_top')
  check_eq(Editor_state.cursor1.line, 2, 'F - test_down_arrow_moves_cursor/cursor')
  -- the screen is unchanged
  y = Editor_state.top
  App.screen.check(y, 'abc', 'F - test_down_arrow_moves_cursor/screen:1')
  y = y + Editor_state.line_height
  App.screen.check(y, 'def', 'F - test_down_arrow_moves_cursor/screen:2')
  y = y + Editor_state.line_height
  App.screen.check(y, 'ghi', 'F - test_down_arrow_moves_cursor/screen:3')
end

function test_down_arrow_scrolls_down_by_one_line()
  io.write('\ntest_down_arrow_scrolls_down_by_one_line')
  -- display the first three lines with the cursor on the bottom line
  App.screen.init{width=120, height=60}
  Editor_state = edit.initialize_test_state()
  Editor_state.lines = load_array{'abc', 'def', 'ghi', 'jkl'}
  Text.redraw_all(Editor_state)
  Editor_state.cursor1 = {line=3, pos=1}
  Editor_state.screen_top1 = {line=1, pos=1}
  Editor_state.screen_bottom1 = {}
  edit.draw(Editor_state)
  local y = Editor_state.top
  App.screen.check(y, 'abc', 'F - test_down_arrow_scrolls_down_by_one_line/baseline/screen:1')
  y = y + Editor_state.line_height
  App.screen.check(y, 'def', 'F - test_down_arrow_scrolls_down_by_one_line/baseline/screen:2')
  y = y + Editor_state.line_height
  App.screen.check(y, 'ghi', 'F - test_down_arrow_scrolls_down_by_one_line/baseline/screen:3')
  -- after hitting the down arrow the screen scrolls down by one line
  edit.run_after_keychord(Editor_state, 'down')
  check_eq(Editor_state.screen_top1.line, 2, 'F - test_down_arrow_scrolls_down_by_one_line/screen_top')
  check_eq(Editor_state.cursor1.line, 4, 'F - test_down_arrow_scrolls_down_by_one_line/cursor')
  y = Editor_state.top
  App.screen.check(y, 'def', 'F - test_down_arrow_scrolls_down_by_one_line/screen:1')
  y = y + Editor_state.line_height
  App.screen.check(y, 'ghi', 'F - test_down_arrow_scrolls_down_by_one_line/screen:2')
  y = y + Editor_state.line_height
  App.screen.check(y, 'jkl', 'F - test_down_arrow_scrolls_down_by_one_line/screen:3')
end

function test_down_arrow_scrolls_down_by_one_screen_line()
  io.write('\ntest_down_arrow_scrolls_down_by_one_screen_line')
  -- display the first three lines with the cursor on the bottom line
  App.screen.init{width=Editor_state.left+30, height=60}
  Editor_state = edit.initialize_test_state()
  Editor_state.lines = load_array{'abc', 'def', 'ghi jkl', 'mno'}
  Text.redraw_all(Editor_state)
  Editor_state.cursor1 = {line=3, pos=1}
  Editor_state.screen_top1 = {line=1, pos=1}
  Editor_state.screen_bottom1 = {}
  edit.draw(Editor_state)
  local y = Editor_state.top
  App.screen.check(y, 'abc', 'F - test_down_arrow_scrolls_down_by_one_screen_line/baseline/screen:1')
  y = y + Editor_state.line_height
  App.screen.check(y, 'def', 'F - test_down_arrow_scrolls_down_by_one_screen_line/baseline/screen:2')
  y = y + Editor_state.line_height
  App.screen.check(y, 'ghi ', 'F - test_down_arrow_scrolls_down_by_one_screen_line/baseline/screen:3')  -- line wrapping includes trailing whitespace
  -- after hitting the down arrow the screen scrolls down by one line
  edit.run_after_keychord(Editor_state, 'down')
  check_eq(Editor_state.screen_top1.line, 2, 'F - test_down_arrow_scrolls_down_by_one_screen_line/screen_top')
  check_eq(Editor_state.cursor1.line, 3, 'F - test_down_arrow_scrolls_down_by_one_screen_line/cursor:line')
  check_eq(Editor_state.cursor1.pos, 5, 'F - test_down_arrow_scrolls_down_by_one_screen_line/cursor:pos')
  y = Editor_state.top
  App.screen.check(y, 'def', 'F - test_down_arrow_scrolls_down_by_one_screen_line/screen:1')
  y = y + Editor_state.line_height
  App.screen.check(y, 'ghi ', 'F - test_down_arrow_scrolls_down_by_one_screen_line/screen:2')
  y = y + Editor_state.line_height
  App.screen.check(y, 'jkl', 'F - test_down_arrow_scrolls_down_by_one_screen_line/screen:3')
end

function test_down_arrow_scrolls_down_by_one_screen_line_after_splitting_within_word()
  io.write('\ntest_down_arrow_scrolls_down_by_one_screen_line_after_splitting_within_word')
  -- display the first three lines with the cursor on the bottom line
  App.screen.init{width=Editor_state.left+30, height=60}
  Editor_state = edit.initialize_test_state()
  Editor_state.lines = load_array{'abc', 'def', 'ghijkl', 'mno'}
  Text.redraw_all(Editor_state)
  Editor_state.cursor1 = {line=3, pos=1}
  Editor_state.screen_top1 = {line=1, pos=1}
  Editor_state.screen_bottom1 = {}
  edit.draw(Editor_state)
  local y = Editor_state.top
  App.screen.check(y, 'abc', 'F - test_down_arrow_scrolls_down_by_one_screen_line_after_splitting_within_word/baseline/screen:1')
  y = y + Editor_state.line_height
  App.screen.check(y, 'def', 'F - test_down_arrow_scrolls_down_by_one_screen_line_after_splitting_within_word/baseline/screen:2')
  y = y + Editor_state.line_height
  App.screen.check(y, 'ghij', 'F - test_down_arrow_scrolls_down_by_one_screen_line_after_splitting_within_word/baseline/screen:3')
  -- after hitting the down arrow the screen scrolls down by one line
  edit.run_after_keychord(Editor_state, 'down')
  check_eq(Editor_state.screen_top1.line, 2, 'F - test_down_arrow_scrolls_down_by_one_screen_line_after_splitting_within_word/screen_top')
  check_eq(Editor_state.cursor1.line, 3, 'F - test_down_arrow_scrolls_down_by_one_screen_line_after_splitting_within_word/cursor:line')
  check_eq(Editor_state.cursor1.pos, 5, 'F - test_down_arrow_scrolls_down_by_one_screen_line_after_splitting_within_word/cursor:pos')
  y = Editor_state.top
  App.screen.check(y, 'def', 'F - test_down_arrow_scrolls_down_by_one_screen_line_after_splitting_within_word/screen:1')
  y = y + Editor_state.line_height
  App.screen.check(y, 'ghij', 'F - test_down_arrow_scrolls_down_by_one_screen_line_after_splitting_within_word/screen:2')
  y = y + Editor_state.line_height
  App.screen.check(y, 'kl', 'F - test_down_arrow_scrolls_down_by_one_screen_line_after_splitting_within_word/screen:3')
end

function test_page_down_followed_by_down_arrow_does_not_scroll_screen_up()
  io.write('\ntest_page_down_followed_by_down_arrow_does_not_scroll_screen_up')
  App.screen.init{width=Editor_state.left+30, height=60}
  Editor_state = edit.initialize_test_state()
  Editor_state.lines = load_array{'abc', 'def', 'ghijkl', 'mno'}
  Text.redraw_all(Editor_state)
  Editor_state.cursor1 = {line=3, pos=1}
  Editor_state.screen_top1 = {line=1, pos=1}
  Editor_state.screen_bottom1 = {}
  edit.draw(Editor_state)
  local y = Editor_state.top
  App.screen.check(y, 'abc', 'F - test_page_down_followed_by_down_arrow_does_not_scroll_screen_up/baseline/screen:1')
  y = y + Editor_state.line_height
  App.screen.check(y, 'def', 'F - test_page_down_followed_by_down_arrow_does_not_scroll_screen_up/baseline/screen:2')
  y = y + Editor_state.line_height
  App.screen.check(y, 'ghij', 'F - test_page_down_followed_by_down_arrow_does_not_scroll_screen_up/baseline/screen:3')
  -- after hitting pagedown the screen scrolls down to start of a long line
  edit.run_after_keychord(Editor_state, 'pagedown')
  check_eq(Editor_state.screen_top1.line, 3, 'F - test_page_down_followed_by_down_arrow_does_not_scroll_screen_up/baseline2/screen_top')
  check_eq(Editor_state.cursor1.line, 3, 'F - test_page_down_followed_by_down_arrow_does_not_scroll_screen_up/baseline2/cursor:line')
  check_eq(Editor_state.cursor1.pos, 1, 'F - test_page_down_followed_by_down_arrow_does_not_scroll_screen_up/baseline2/cursor:pos')
  -- after hitting down arrow the screen doesn't scroll down further, and certainly doesn't scroll up
  edit.run_after_keychord(Editor_state, 'down')
  check_eq(Editor_state.screen_top1.line, 3, 'F - test_page_down_followed_by_down_arrow_does_not_scroll_screen_up/screen_top')
  check_eq(Editor_state.cursor1.line, 3, 'F - test_page_down_followed_by_down_arrow_does_not_scroll_screen_up/cursor:line')
  check_eq(Editor_state.cursor1.pos, 5, 'F - test_page_down_followed_by_down_arrow_does_not_scroll_screen_up/cursor:pos')
  y = Editor_state.top
  App.screen.check(y, 'ghij', 'F - test_page_down_followed_by_down_arrow_does_not_scroll_screen_up/screen:1')
  y = y + Editor_state.line_height
  App.screen.check(y, 'kl', 'F - test_page_down_followed_by_down_arrow_does_not_scroll_screen_up/screen:2')
  y = y + Editor_state.line_height
  App.screen.check(y, 'mno', 'F - test_page_down_followed_by_down_arrow_does_not_scroll_screen_up/screen:3')
end

function test_up_arrow_moves_cursor()
  io.write('\ntest_up_arrow_moves_cursor')
  -- display the first 3 lines with the cursor on the bottom line
  App.screen.init{width=120, height=60}
  Editor_state = edit.initialize_test_state()
  Editor_state.lines = load_array{'abc', 'def', 'ghi', 'jkl'}
  Text.redraw_all(Editor_state)
  Editor_state.cursor1 = {line=3, pos=1}
  Editor_state.screen_top1 = {line=1, pos=1}
  Editor_state.screen_bottom1 = {}
  edit.draw(Editor_state)
  local y = Editor_state.top
  App.screen.check(y, 'abc', 'F - test_up_arrow_moves_cursor/baseline/screen:1')
  y = y + Editor_state.line_height
  App.screen.check(y, 'def', 'F - test_up_arrow_moves_cursor/baseline/screen:2')
  y = y + Editor_state.line_height
  App.screen.check(y, 'ghi', 'F - test_up_arrow_moves_cursor/baseline/screen:3')
  -- after hitting the up arrow the cursor moves up by 1 line
  edit.run_after_keychord(Editor_state, 'up')
  check_eq(Editor_state.screen_top1.line, 1, 'F - test_up_arrow_moves_cursor/screen_top')
  check_eq(Editor_state.cursor1.line, 2, 'F - test_up_arrow_moves_cursor/cursor')
  -- the screen is unchanged
  y = Editor_state.top
  App.screen.check(y, 'abc', 'F - test_up_arrow_moves_cursor/screen:1')
  y = y + Editor_state.line_height
  App.screen.check(y, 'def', 'F - test_up_arrow_moves_cursor/screen:2')
  y = y + Editor_state.line_height
  App.screen.check(y, 'ghi', 'F - test_up_arrow_moves_cursor/screen:3')
end

function test_up_arrow_scrolls_up_by_one_line()
  io.write('\ntest_up_arrow_scrolls_up_by_one_line')
  -- display the lines 2/3/4 with the cursor on line 2
  App.screen.init{width=120, height=60}
  Editor_state = edit.initialize_test_state()
  Editor_state.lines = load_array{'abc', 'def', 'ghi', 'jkl'}
  Text.redraw_all(Editor_state)
  Editor_state.cursor1 = {line=2, pos=1}
  Editor_state.screen_top1 = {line=2, pos=1}
  Editor_state.screen_bottom1 = {}
  edit.draw(Editor_state)
  local y = Editor_state.top
  App.screen.check(y, 'def', 'F - test_up_arrow_scrolls_up_by_one_line/baseline/screen:1')
  y = y + Editor_state.line_height
  App.screen.check(y, 'ghi', 'F - test_up_arrow_scrolls_up_by_one_line/baseline/screen:2')
  y = y + Editor_state.line_height
  App.screen.check(y, 'jkl', 'F - test_up_arrow_scrolls_up_by_one_line/baseline/screen:3')
  -- after hitting the up arrow the screen scrolls up by one line
  edit.run_after_keychord(Editor_state, 'up')
  check_eq(Editor_state.screen_top1.line, 1, 'F - test_up_arrow_scrolls_up_by_one_line/screen_top')
  check_eq(Editor_state.cursor1.line, 1, 'F - test_up_arrow_scrolls_up_by_one_line/cursor')
  y = Editor_state.top
  App.screen.check(y, 'abc', 'F - test_up_arrow_scrolls_up_by_one_line/screen:1')
  y = y + Editor_state.line_height
  App.screen.check(y, 'def', 'F - test_up_arrow_scrolls_up_by_one_line/screen:2')
  y = y + Editor_state.line_height
  App.screen.check(y, 'ghi', 'F - test_up_arrow_scrolls_up_by_one_line/screen:3')
end

function test_up_arrow_scrolls_up_by_one_screen_line()
  io.write('\ntest_up_arrow_scrolls_up_by_one_screen_line')
  -- display lines starting from second screen line of a line
  App.screen.init{width=Editor_state.left+30, height=60}
  Editor_state = edit.initialize_test_state()
  Editor_state.lines = load_array{'abc', 'def', 'ghi jkl', 'mno'}
  Text.redraw_all(Editor_state)
  Editor_state.cursor1 = {line=3, pos=6}
  Editor_state.screen_top1 = {line=3, pos=5}
  Editor_state.screen_bottom1 = {}
  edit.draw(Editor_state)
  local y = Editor_state.top
  App.screen.check(y, 'jkl', 'F - test_up_arrow_scrolls_up_by_one_screen_line/baseline/screen:1')
  y = y + Editor_state.line_height
  App.screen.check(y, 'mno', 'F - test_up_arrow_scrolls_up_by_one_screen_line/baseline/screen:2')
  -- after hitting the up arrow the screen scrolls up to first screen line
  edit.run_after_keychord(Editor_state, 'up')
  y = Editor_state.top
  App.screen.check(y, 'ghi ', 'F - test_up_arrow_scrolls_up_by_one_screen_line/screen:1')
  y = y + Editor_state.line_height
  App.screen.check(y, 'jkl', 'F - test_up_arrow_scrolls_up_by_one_screen_line/screen:2')
  y = y + Editor_state.line_height
  App.screen.check(y, 'mno', 'F - test_up_arrow_scrolls_up_by_one_screen_line/screen:3')
  check_eq(Editor_state.screen_top1.line, 3, 'F - test_up_arrow_scrolls_up_by_one_screen_line/screen_top')
  check_eq(Editor_state.screen_top1.pos, 1, 'F - test_up_arrow_scrolls_up_by_one_screen_line/screen_top')
  check_eq(Editor_state.cursor1.line, 3, 'F - test_up_arrow_scrolls_up_by_one_screen_line/cursor:line')
  check_eq(Editor_state.cursor1.pos, 1, 'F - test_up_arrow_scrolls_up_by_one_screen_line/cursor:pos')
end

function test_up_arrow_scrolls_up_to_final_screen_line()
  io.write('\ntest_up_arrow_scrolls_up_to_final_screen_line')
  -- display lines starting just after a long line
  App.screen.init{width=Editor_state.left+30, height=60}
  Editor_state = edit.initialize_test_state()
  Editor_state.lines = load_array{'abc def', 'ghi', 'jkl', 'mno'}
  Text.redraw_all(Editor_state)
  Editor_state.cursor1 = {line=2, pos=1}
  Editor_state.screen_top1 = {line=2, pos=1}
  Editor_state.screen_bottom1 = {}
  edit.draw(Editor_state)
  local y = Editor_state.top
  App.screen.check(y, 'ghi', 'F - test_up_arrow_scrolls_up_to_final_screen_line/baseline/screen:1')
  y = y + Editor_state.line_height
  App.screen.check(y, 'jkl', 'F - test_up_arrow_scrolls_up_to_final_screen_line/baseline/screen:2')
  y = y + Editor_state.line_height
  App.screen.check(y, 'mno', 'F - test_up_arrow_scrolls_up_to_final_screen_line/baseline/screen:3')
  -- after hitting the up arrow the screen scrolls up to final screen line of previous line
  edit.run_after_keychord(Editor_state, 'up')
  y = Editor_state.top
  App.screen.check(y, 'def', 'F - test_up_arrow_scrolls_up_to_final_screen_line/screen:1')
  y = y + Editor_state.line_height
  App.screen.check(y, 'ghi', 'F - test_up_arrow_scrolls_up_to_final_screen_line/screen:2')
  y = y + Editor_state.line_height
  App.screen.check(y, 'jkl', 'F - test_up_arrow_scrolls_up_to_final_screen_line/screen:3')
  check_eq(Editor_state.screen_top1.line, 1, 'F - test_up_arrow_scrolls_up_to_final_screen_line/screen_top')
  check_eq(Editor_state.screen_top1.pos, 5, 'F - test_up_arrow_scrolls_up_to_final_screen_line/screen_top')
  check_eq(Editor_state.cursor1.line, 1, 'F - test_up_arrow_scrolls_up_to_final_screen_line/cursor:line')
  check_eq(Editor_state.cursor1.pos, 5, 'F - test_up_arrow_scrolls_up_to_final_screen_line/cursor:pos')
end

function test_up_arrow_scrolls_up_to_empty_line()
  io.write('\ntest_up_arrow_scrolls_up_to_empty_line')
  -- display a screenful of text with an empty line just above it outside the screen
  App.screen.init{width=120, height=60}
  Editor_state = edit.initialize_test_state()
  Editor_state.lines = load_array{'', 'abc', 'def', 'ghi', 'jkl'}
  Text.redraw_all(Editor_state)
  Editor_state.cursor1 = {line=2, pos=1}
  Editor_state.screen_top1 = {line=2, pos=1}
  Editor_state.screen_bottom1 = {}
  edit.draw(Editor_state)
  local y = Editor_state.top
  App.screen.check(y, 'abc', 'F - test_up_arrow_scrolls_up_to_empty_line/baseline/screen:1')
  y = y + Editor_state.line_height
  App.screen.check(y, 'def', 'F - test_up_arrow_scrolls_up_to_empty_line/baseline/screen:2')
  y = y + Editor_state.line_height
  App.screen.check(y, 'ghi', 'F - test_up_arrow_scrolls_up_to_empty_line/baseline/screen:3')
  -- after hitting the up arrow the screen scrolls up by one line
  edit.run_after_keychord(Editor_state, 'up')
  check_eq(Editor_state.screen_top1.line, 1, 'F - test_up_arrow_scrolls_up_to_empty_line/screen_top')
  check_eq(Editor_state.cursor1.line, 1, 'F - test_up_arrow_scrolls_up_to_empty_line/cursor')
  y = Editor_state.top
  -- empty first line
  y = y + Editor_state.line_height
  App.screen.check(y, 'abc', 'F - test_up_arrow_scrolls_up_to_empty_line/screen:2')
  y = y + Editor_state.line_height
  App.screen.check(y, 'def', 'F - test_up_arrow_scrolls_up_to_empty_line/screen:3')
end

function test_pageup()
  io.write('\ntest_pageup')
  App.screen.init{width=120, height=45}
  Editor_state = edit.initialize_test_state()
  Editor_state.lines = load_array{'abc', 'def', 'ghi'}
  Text.redraw_all(Editor_state)
  Editor_state.cursor1 = {line=2, pos=1}
  Editor_state.screen_top1 = {line=2, pos=1}
  Editor_state.screen_bottom1 = {}
  -- initially the last two lines are displayed
  edit.draw(Editor_state)
  local y = Editor_state.top
  App.screen.check(y, 'def', 'F - test_pageup/baseline/screen:1')
  y = y + Editor_state.line_height
  App.screen.check(y, 'ghi', 'F - test_pageup/baseline/screen:2')
  -- after pageup the cursor goes to first line
  edit.run_after_keychord(Editor_state, 'pageup')
  check_eq(Editor_state.screen_top1.line, 1, 'F - test_pageup/screen_top')
  check_eq(Editor_state.cursor1.line, 1, 'F - test_pageup/cursor')
  y = Editor_state.top
  App.screen.check(y, 'abc', 'F - test_pageup/screen:1')
  y = y + Editor_state.line_height
  App.screen.check(y, 'def', 'F - test_pageup/screen:2')
end

function test_pageup_scrolls_up_by_screen_line()
  io.write('\ntest_pageup_scrolls_up_by_screen_line')
  -- display the first three lines with the cursor on the bottom line
  App.screen.init{width=Editor_state.left+30, height=60}
  Editor_state = edit.initialize_test_state()
  Editor_state.lines = load_array{'abc def', 'ghi', 'jkl', 'mno'}
  Text.redraw_all(Editor_state)
  Editor_state.cursor1 = {line=2, pos=1}
  Editor_state.screen_top1 = {line=2, pos=1}
  Editor_state.screen_bottom1 = {}
  edit.draw(Editor_state)
  local y = Editor_state.top
  App.screen.check(y, 'ghi', 'F - test_pageup_scrolls_up_by_screen_line/baseline/screen:1')
  y = y + Editor_state.line_height
  App.screen.check(y, 'jkl', 'F - test_pageup_scrolls_up_by_screen_line/baseline/screen:2')
  y = y + Editor_state.line_height
  App.screen.check(y, 'mno', 'F - test_pageup_scrolls_up_by_screen_line/baseline/screen:3')  -- line wrapping includes trailing whitespace
  -- after hitting the page-up key the screen scrolls up to top
  edit.run_after_keychord(Editor_state, 'pageup')
  check_eq(Editor_state.screen_top1.line, 1, 'F - test_pageup_scrolls_up_by_screen_line/screen_top')
  check_eq(Editor_state.cursor1.line, 1, 'F - test_pageup_scrolls_up_by_screen_line/cursor:line')
  check_eq(Editor_state.cursor1.pos, 1, 'F - test_pageup_scrolls_up_by_screen_line/cursor:pos')
  y = Editor_state.top
  App.screen.check(y, 'abc ', 'F - test_pageup_scrolls_up_by_screen_line/screen:1')
  y = y + Editor_state.line_height
  App.screen.check(y, 'def', 'F - test_pageup_scrolls_up_by_screen_line/screen:2')
  y = y + Editor_state.line_height
  App.screen.check(y, 'ghi', 'F - test_pageup_scrolls_up_by_screen_line/screen:3')
end

function test_pageup_scrolls_up_from_middle_screen_line()
  io.write('\ntest_pageup_scrolls_up_from_middle_screen_line')
  -- display a few lines starting from the middle of a line (Editor_state.cursor1.pos > 1)
  App.screen.init{width=Editor_state.left+30, height=60}
  Editor_state = edit.initialize_test_state()
  Editor_state.lines = load_array{'abc def', 'ghi jkl', 'mno'}
  Text.redraw_all(Editor_state)
  Editor_state.cursor1 = {line=2, pos=5}
  Editor_state.screen_top1 = {line=2, pos=5}
  Editor_state.screen_bottom1 = {}
  edit.draw(Editor_state)
  local y = Editor_state.top
  App.screen.check(y, 'jkl', 'F - test_pageup_scrolls_up_from_middle_screen_line/baseline/screen:2')
  y = y + Editor_state.line_height
  App.screen.check(y, 'mno', 'F - test_pageup_scrolls_up_from_middle_screen_line/baseline/screen:3')  -- line wrapping includes trailing whitespace
  -- after hitting the page-up key the screen scrolls up to top
  edit.run_after_keychord(Editor_state, 'pageup')
  check_eq(Editor_state.screen_top1.line, 1, 'F - test_pageup_scrolls_up_from_middle_screen_line/screen_top')
  check_eq(Editor_state.cursor1.line, 1, 'F - test_pageup_scrolls_up_from_middle_screen_line/cursor:line')
  check_eq(Editor_state.cursor1.pos, 1, 'F - test_pageup_scrolls_up_from_middle_screen_line/cursor:pos')
  y = Editor_state.top
  App.screen.check(y, 'abc ', 'F - test_pageup_scrolls_up_from_middle_screen_line/screen:1')
  y = y + Editor_state.line_height
  App.screen.check(y, 'def', 'F - test_pageup_scrolls_up_from_middle_screen_line/screen:2')
  y = y + Editor_state.line_height
  App.screen.check(y, 'ghi ', 'F - test_pageup_scrolls_up_from_middle_screen_line/screen:3')
end

function test_enter_on_bottom_line_scrolls_down()
  io.write('\ntest_enter_on_bottom_line_scrolls_down')
  -- display a few lines with cursor on bottom line
  App.screen.init{width=Editor_state.left+30, height=60}
  Editor_state = edit.initialize_test_state()
  Editor_state.lines = load_array{'abc', 'def', 'ghi', 'jkl'}
  Text.redraw_all(Editor_state)
  Editor_state.cursor1 = {line=3, pos=2}
  Editor_state.screen_top1 = {line=1, pos=1}
  Editor_state.screen_bottom1 = {}
  edit.draw(Editor_state)
  local y = Editor_state.top
  App.screen.check(y, 'abc', 'F - test_enter_on_bottom_line_scrolls_down/baseline/screen:1')
  y = y + Editor_state.line_height
  App.screen.check(y, 'def', 'F - test_enter_on_bottom_line_scrolls_down/baseline/screen:2')
  y = y + Editor_state.line_height
  App.screen.check(y, 'ghi', 'F - test_enter_on_bottom_line_scrolls_down/baseline/screen:3')
  -- after hitting the enter key the screen scrolls down
  edit.run_after_keychord(Editor_state, 'return')
  check_eq(Editor_state.screen_top1.line, 2, 'F - test_enter_on_bottom_line_scrolls_down/screen_top')
  check_eq(Editor_state.cursor1.line, 4, 'F - test_enter_on_bottom_line_scrolls_down/cursor:line')
  check_eq(Editor_state.cursor1.pos, 1, 'F - test_enter_on_bottom_line_scrolls_down/cursor:pos')
  y = Editor_state.top
  App.screen.check(y, 'def', 'F - test_enter_on_bottom_line_scrolls_down/screen:1')
  y = y + Editor_state.line_height
  App.screen.check(y, 'g', 'F - test_enter_on_bottom_line_scrolls_down/screen:2')
  y = y + Editor_state.line_height
  App.screen.check(y, 'hi', 'F - test_enter_on_bottom_line_scrolls_down/screen:3')
end

function test_enter_on_final_line_avoids_scrolling_down_when_not_at_bottom()
  io.write('\ntest_enter_on_final_line_avoids_scrolling_down_when_not_at_bottom')
  -- display just the bottom line on screen
  App.screen.init{width=Editor_state.left+30, height=60}
  Editor_state = edit.initialize_test_state()
  Editor_state.lines = load_array{'abc', 'def', 'ghi', 'jkl'}
  Text.redraw_all(Editor_state)
  Editor_state.cursor1 = {line=4, pos=2}
  Editor_state.screen_top1 = {line=4, pos=1}
  Editor_state.screen_bottom1 = {}
  edit.draw(Editor_state)
  local y = Editor_state.top
  App.screen.check(y, 'jkl', 'F - test_enter_on_final_line_avoids_scrolling_down_when_not_at_bottom/baseline/screen:1')
  -- after hitting the enter key the screen does not scroll down
  edit.run_after_keychord(Editor_state, 'return')
  check_eq(Editor_state.screen_top1.line, 4, 'F - test_enter_on_final_line_avoids_scrolling_down_when_not_at_bottom/screen_top')
  check_eq(Editor_state.cursor1.line, 5, 'F - test_enter_on_final_line_avoids_scrolling_down_when_not_at_bottom/cursor:line')
  check_eq(Editor_state.cursor1.pos, 1, 'F - test_enter_on_final_line_avoids_scrolling_down_when_not_at_bottom/cursor:pos')
  y = Editor_state.top
  App.screen.check(y, 'j', 'F - test_enter_on_final_line_avoids_scrolling_down_when_not_at_bottom/screen:1')
  y = y + Editor_state.line_height
  App.screen.check(y, 'kl', 'F - test_enter_on_final_line_avoids_scrolling_down_when_not_at_bottom/screen:2')
end

function test_inserting_text_on_final_line_avoids_scrolling_down_when_not_at_bottom()
  io.write('\ntest_inserting_text_on_final_line_avoids_scrolling_down_when_not_at_bottom')
  -- display just an empty bottom line on screen
  App.screen.init{width=Editor_state.left+30, height=60}
  Editor_state = edit.initialize_test_state()
  Editor_state.lines = load_array{'abc', ''}
  Text.redraw_all(Editor_state)
  Editor_state.cursor1 = {line=2, pos=1}
  Editor_state.screen_top1 = {line=2, pos=1}
  Editor_state.screen_bottom1 = {}
  edit.draw(Editor_state)
  -- after hitting the inserting_text key the screen does not scroll down
  edit.run_after_textinput(Editor_state, 'a')
  check_eq(Editor_state.screen_top1.line, 2, 'F - test_inserting_text_on_final_line_avoids_scrolling_down_when_not_at_bottom/screen_top')
  check_eq(Editor_state.cursor1.line, 2, 'F - test_inserting_text_on_final_line_avoids_scrolling_down_when_not_at_bottom/cursor:line')
  check_eq(Editor_state.cursor1.pos, 2, 'F - test_inserting_text_on_final_line_avoids_scrolling_down_when_not_at_bottom/cursor:pos')
  local y = Editor_state.top
  App.screen.check(y, 'a', 'F - test_inserting_text_on_final_line_avoids_scrolling_down_when_not_at_bottom/screen:1')
end

function test_typing_on_bottom_line_scrolls_down()
  io.write('\ntest_typing_on_bottom_line_scrolls_down')
  -- display a few lines with cursor on bottom line
  App.screen.init{width=Editor_state.left+30, height=60}
  Editor_state = edit.initialize_test_state()
  Editor_state.lines = load_array{'abc', 'def', 'ghi', 'jkl'}
  Text.redraw_all(Editor_state)
  Editor_state.cursor1 = {line=3, pos=4}
  Editor_state.screen_top1 = {line=1, pos=1}
  Editor_state.screen_bottom1 = {}
  edit.draw(Editor_state)
  local y = Editor_state.top
  App.screen.check(y, 'abc', 'F - test_typing_on_bottom_line_scrolls_down/baseline/screen:1')
  y = y + Editor_state.line_height
  App.screen.check(y, 'def', 'F - test_typing_on_bottom_line_scrolls_down/baseline/screen:2')
  y = y + Editor_state.line_height
  App.screen.check(y, 'ghi', 'F - test_typing_on_bottom_line_scrolls_down/baseline/screen:3')
  -- after typing something the line wraps and the screen scrolls down
  edit.run_after_textinput(Editor_state, 'j')
  edit.run_after_textinput(Editor_state, 'k')
  edit.run_after_textinput(Editor_state, 'l')
  check_eq(Editor_state.screen_top1.line, 2, 'F - test_typing_on_bottom_line_scrolls_down/screen_top')
  check_eq(Editor_state.cursor1.line, 3, 'F - test_typing_on_bottom_line_scrolls_down/cursor:line')
  check_eq(Editor_state.cursor1.pos, 7, 'F - test_typing_on_bottom_line_scrolls_down/cursor:pos')
  y = Editor_state.top
  App.screen.check(y, 'def', 'F - test_typing_on_bottom_line_scrolls_down/screen:1')
  y = y + Editor_state.line_height
  App.screen.check(y, 'ghij', 'F - test_typing_on_bottom_line_scrolls_down/screen:2')
  y = y + Editor_state.line_height
  App.screen.check(y, 'kl', 'F - test_typing_on_bottom_line_scrolls_down/screen:3')
end

function test_left_arrow_scrolls_up_in_wrapped_line()
  io.write('\ntest_left_arrow_scrolls_up_in_wrapped_line')
  -- display lines starting from second screen line of a line
  App.screen.init{width=Editor_state.left+30, height=60}
  Editor_state = edit.initialize_test_state()
  Editor_state.lines = load_array{'abc', 'def', 'ghi jkl', 'mno'}
  Text.redraw_all(Editor_state)
  Editor_state.screen_top1 = {line=3, pos=5}
  Editor_state.screen_bottom1 = {}
  -- cursor is at top of screen
  Editor_state.cursor1 = {line=3, pos=5}
  edit.draw(Editor_state)
  local y = Editor_state.top
  App.screen.check(y, 'jkl', 'F - test_left_arrow_scrolls_up_in_wrapped_line/baseline/screen:1')
  y = y + Editor_state.line_height
  App.screen.check(y, 'mno', 'F - test_left_arrow_scrolls_up_in_wrapped_line/baseline/screen:2')
  -- after hitting the left arrow the screen scrolls up to first screen line
  edit.run_after_keychord(Editor_state, 'left')
  y = Editor_state.top
  App.screen.check(y, 'ghi ', 'F - test_left_arrow_scrolls_up_in_wrapped_line/screen:1')
  y = y + Editor_state.line_height
  App.screen.check(y, 'jkl', 'F - test_left_arrow_scrolls_up_in_wrapped_line/screen:2')
  y = y + Editor_state.line_height
  App.screen.check(y, 'mno', 'F - test_left_arrow_scrolls_up_in_wrapped_line/screen:3')
  check_eq(Editor_state.screen_top1.line, 3, 'F - test_left_arrow_scrolls_up_in_wrapped_line/screen_top')
  check_eq(Editor_state.screen_top1.pos, 1, 'F - test_left_arrow_scrolls_up_in_wrapped_line/screen_top')
  check_eq(Editor_state.cursor1.line, 3, 'F - test_left_arrow_scrolls_up_in_wrapped_line/cursor:line')
  check_eq(Editor_state.cursor1.pos, 4, 'F - test_left_arrow_scrolls_up_in_wrapped_line/cursor:pos')
end

function test_right_arrow_scrolls_down_in_wrapped_line()
  io.write('\ntest_right_arrow_scrolls_down_in_wrapped_line')
  -- display the first three lines with the cursor on the bottom line
  App.screen.init{width=Editor_state.left+30, height=60}
  Editor_state = edit.initialize_test_state()
  Editor_state.lines = load_array{'abc', 'def', 'ghi jkl', 'mno'}
  Text.redraw_all(Editor_state)
  Editor_state.screen_top1 = {line=1, pos=1}
  Editor_state.screen_bottom1 = {}
  -- cursor is at bottom right of screen
  Editor_state.cursor1 = {line=3, pos=5}
  edit.draw(Editor_state)
  local y = Editor_state.top
  App.screen.check(y, 'abc', 'F - test_right_arrow_scrolls_down_in_wrapped_line/baseline/screen:1')
  y = y + Editor_state.line_height
  App.screen.check(y, 'def', 'F - test_right_arrow_scrolls_down_in_wrapped_line/baseline/screen:2')
  y = y + Editor_state.line_height
  App.screen.check(y, 'ghi ', 'F - test_right_arrow_scrolls_down_in_wrapped_line/baseline/screen:3')  -- line wrapping includes trailing whitespace
  -- after hitting the right arrow the screen scrolls down by one line
  edit.run_after_keychord(Editor_state, 'right')
  check_eq(Editor_state.screen_top1.line, 2, 'F - test_right_arrow_scrolls_down_in_wrapped_line/screen_top')
  check_eq(Editor_state.cursor1.line, 3, 'F - test_right_arrow_scrolls_down_in_wrapped_line/cursor:line')
  check_eq(Editor_state.cursor1.pos, 6, 'F - test_right_arrow_scrolls_down_in_wrapped_line/cursor:pos')
  y = Editor_state.top
  App.screen.check(y, 'def', 'F - test_right_arrow_scrolls_down_in_wrapped_line/screen:1')
  y = y + Editor_state.line_height
  App.screen.check(y, 'ghi ', 'F - test_right_arrow_scrolls_down_in_wrapped_line/screen:2')
  y = y + Editor_state.line_height
  App.screen.check(y, 'jkl', 'F - test_right_arrow_scrolls_down_in_wrapped_line/screen:3')
end

function test_home_scrolls_up_in_wrapped_line()
  io.write('\ntest_home_scrolls_up_in_wrapped_line')
  -- display lines starting from second screen line of a line
  App.screen.init{width=Editor_state.left+30, height=60}
  Editor_state = edit.initialize_test_state()
  Editor_state.lines = load_array{'abc', 'def', 'ghi jkl', 'mno'}
  Text.redraw_all(Editor_state)
  Editor_state.screen_top1 = {line=3, pos=5}
  Editor_state.screen_bottom1 = {}
  -- cursor is at top of screen
  Editor_state.cursor1 = {line=3, pos=5}
  edit.draw(Editor_state)
  local y = Editor_state.top
  App.screen.check(y, 'jkl', 'F - test_home_scrolls_up_in_wrapped_line/baseline/screen:1')
  y = y + Editor_state.line_height
  App.screen.check(y, 'mno', 'F - test_home_scrolls_up_in_wrapped_line/baseline/screen:2')
  -- after hitting home the screen scrolls up to first screen line
  edit.run_after_keychord(Editor_state, 'home')
  y = Editor_state.top
  App.screen.check(y, 'ghi ', 'F - test_home_scrolls_up_in_wrapped_line/screen:1')
  y = y + Editor_state.line_height
  App.screen.check(y, 'jkl', 'F - test_home_scrolls_up_in_wrapped_line/screen:2')
  y = y + Editor_state.line_height
  App.screen.check(y, 'mno', 'F - test_home_scrolls_up_in_wrapped_line/screen:3')
  check_eq(Editor_state.screen_top1.line, 3, 'F - test_home_scrolls_up_in_wrapped_line/screen_top')
  check_eq(Editor_state.screen_top1.pos, 1, 'F - test_home_scrolls_up_in_wrapped_line/screen_top')
  check_eq(Editor_state.cursor1.line, 3, 'F - test_home_scrolls_up_in_wrapped_line/cursor:line')
  check_eq(Editor_state.cursor1.pos, 1, 'F - test_home_scrolls_up_in_wrapped_line/cursor:pos')
end

function test_end_scrolls_down_in_wrapped_line()
  io.write('\ntest_end_scrolls_down_in_wrapped_line')
  -- display the first three lines with the cursor on the bottom line
  App.screen.init{width=Editor_state.left+30, height=60}
  Editor_state = edit.initialize_test_state()
  Editor_state.lines = load_array{'abc', 'def', 'ghi jkl', 'mno'}
  Text.redraw_all(Editor_state)
  Editor_state.screen_top1 = {line=1, pos=1}
  Editor_state.screen_bottom1 = {}
  -- cursor is at bottom right of screen
  Editor_state.cursor1 = {line=3, pos=5}
  edit.draw(Editor_state)
  local y = Editor_state.top
  App.screen.check(y, 'abc', 'F - test_end_scrolls_down_in_wrapped_line/baseline/screen:1')
  y = y + Editor_state.line_height
  App.screen.check(y, 'def', 'F - test_end_scrolls_down_in_wrapped_line/baseline/screen:2')
  y = y + Editor_state.line_height
  App.screen.check(y, 'ghi ', 'F - test_end_scrolls_down_in_wrapped_line/baseline/screen:3')  -- line wrapping includes trailing whitespace
  -- after hitting end the screen scrolls down by one line
  edit.run_after_keychord(Editor_state, 'end')
  check_eq(Editor_state.screen_top1.line, 2, 'F - test_end_scrolls_down_in_wrapped_line/screen_top')
  check_eq(Editor_state.cursor1.line, 3, 'F - test_end_scrolls_down_in_wrapped_line/cursor:line')
  check_eq(Editor_state.cursor1.pos, 8, 'F - test_end_scrolls_down_in_wrapped_line/cursor:pos')
  y = Editor_state.top
  App.screen.check(y, 'def', 'F - test_end_scrolls_down_in_wrapped_line/screen:1')
  y = y + Editor_state.line_height
  App.screen.check(y, 'ghi ', 'F - test_end_scrolls_down_in_wrapped_line/screen:2')
  y = y + Editor_state.line_height
  App.screen.check(y, 'jkl', 'F - test_end_scrolls_down_in_wrapped_line/screen:3')
end

function test_position_cursor_on_recently_edited_wrapping_line()
  -- draw a line wrapping over 2 screen lines
  io.write('\ntest_position_cursor_on_recently_edited_wrapping_line')
  App.screen.init{width=100, height=200}
  Editor_state = edit.initialize_test_state()
  Editor_state.lines = load_array{'abc def ghi jkl mno pqr ', 'xyz'}
  Text.redraw_all(Editor_state)
  Editor_state.cursor1 = {line=1, pos=25}
  Editor_state.screen_top1 = {line=1, pos=1}
  Editor_state.screen_bottom1 = {}
  edit.draw(Editor_state)
  local y = Editor_state.top
  App.screen.check(y, 'abc def ghi ', 'F - test_position_cursor_on_recently_edited_wrapping_line/baseline1/screen:1')
  y = y + Editor_state.line_height
  App.screen.check(y, 'jkl mno pqr ', 'F - test_position_cursor_on_recently_edited_wrapping_line/baseline1/screen:2')
  y = y + Editor_state.line_height
  App.screen.check(y, 'xyz', 'F - test_position_cursor_on_recently_edited_wrapping_line/baseline1/screen:3')
  -- add to the line until it's wrapping over 3 screen lines
  edit.run_after_textinput(Editor_state, 's')
  edit.run_after_textinput(Editor_state, 't')
  edit.run_after_textinput(Editor_state, 'u')
  check_eq(Editor_state.cursor1.pos, 28, 'F - test_position_cursor_on_recently_edited_wrapping_line/cursor:pos')
  y = Editor_state.top
  App.screen.check(y, 'abc def ghi ', 'F - test_position_cursor_on_recently_edited_wrapping_line/baseline2/screen:1')
  y = y + Editor_state.line_height
  App.screen.check(y, 'jkl mno pqr ', 'F - test_position_cursor_on_recently_edited_wrapping_line/baseline2/screen:2')
  y = y + Editor_state.line_height
  App.screen.check(y, 'stu', 'F - test_position_cursor_on_recently_edited_wrapping_line/baseline2/screen:3')
  -- try to move the cursor earlier in the third screen line by clicking the mouse
  edit.run_after_mouse_release(Editor_state, Editor_state.left+8,Editor_state.top+Editor_state.line_height*2+5, 1)
  -- cursor should move
  check_eq(Editor_state.cursor1.line, 1, 'F - test_position_cursor_on_recently_edited_wrapping_line/cursor:line')
  check_eq(Editor_state.cursor1.pos, 26, 'F - test_position_cursor_on_recently_edited_wrapping_line/cursor:pos')
end

function test_backspace_can_scroll_up()
  io.write('\ntest_backspace_can_scroll_up')
  -- display the lines 2/3/4 with the cursor on line 2
  App.screen.init{width=120, height=60}
  Editor_state = edit.initialize_test_state()
  Editor_state.lines = load_array{'abc', 'def', 'ghi', 'jkl'}
  Text.redraw_all(Editor_state)
  Editor_state.cursor1 = {line=2, pos=1}
  Editor_state.screen_top1 = {line=2, pos=1}
  Editor_state.screen_bottom1 = {}
  edit.draw(Editor_state)
  local y = Editor_state.top
  App.screen.check(y, 'def', 'F - test_backspace_can_scroll_up/baseline/screen:1')
  y = y + Editor_state.line_height
  App.screen.check(y, 'ghi', 'F - test_backspace_can_scroll_up/baseline/screen:2')
  y = y + Editor_state.line_height
  App.screen.check(y, 'jkl', 'F - test_backspace_can_scroll_up/baseline/screen:3')
  -- after hitting backspace the screen scrolls up by one line
  edit.run_after_keychord(Editor_state, 'backspace')
  check_eq(Editor_state.screen_top1.line, 1, 'F - test_backspace_can_scroll_up/screen_top')
  check_eq(Editor_state.cursor1.line, 1, 'F - test_backspace_can_scroll_up/cursor')
  y = Editor_state.top
  App.screen.check(y, 'abcdef', 'F - test_backspace_can_scroll_up/screen:1')
  y = y + Editor_state.line_height
  App.screen.check(y, 'ghi', 'F - test_backspace_can_scroll_up/screen:2')
  y = y + Editor_state.line_height
  App.screen.check(y, 'jkl', 'F - test_backspace_can_scroll_up/screen:3')
end

function test_backspace_can_scroll_up_screen_line()
  io.write('\ntest_backspace_can_scroll_up_screen_line')
  -- display lines starting from second screen line of a line
  App.screen.init{width=Editor_state.left+30, height=60}
  Editor_state = edit.initialize_test_state()
  Editor_state.lines = load_array{'abc', 'def', 'ghi jkl', 'mno'}
  Text.redraw_all(Editor_state)
  Editor_state.cursor1 = {line=3, pos=5}
  Editor_state.screen_top1 = {line=3, pos=5}
  Editor_state.screen_bottom1 = {}
  edit.draw(Editor_state)
  local y = Editor_state.top
  App.screen.check(y, 'jkl', 'F - test_backspace_can_scroll_up_screen_line/baseline/screen:1')
  y = y + Editor_state.line_height
  App.screen.check(y, 'mno', 'F - test_backspace_can_scroll_up_screen_line/baseline/screen:2')
  -- after hitting backspace the screen scrolls up by one screen line
  edit.run_after_keychord(Editor_state, 'backspace')
  y = Editor_state.top
  App.screen.check(y, 'ghij', 'F - test_backspace_can_scroll_up_screen_line/screen:1')
  y = y + Editor_state.line_height
  App.screen.check(y, 'kl', 'F - test_backspace_can_scroll_up_screen_line/screen:2')
  y = y + Editor_state.line_height
  App.screen.check(y, 'mno', 'F - test_backspace_can_scroll_up_screen_line/screen:3')
  check_eq(Editor_state.screen_top1.line, 3, 'F - test_backspace_can_scroll_up_screen_line/screen_top')
  check_eq(Editor_state.screen_top1.pos, 1, 'F - test_backspace_can_scroll_up_screen_line/screen_top')
  check_eq(Editor_state.cursor1.line, 3, 'F - test_backspace_can_scroll_up_screen_line/cursor:line')
  check_eq(Editor_state.cursor1.pos, 4, 'F - test_backspace_can_scroll_up_screen_line/cursor:pos')
end

function test_backspace_past_line_boundary()
  io.write('\ntest_backspace_past_line_boundary')
  -- position cursor at start of a (non-first) line
  App.screen.init{width=Editor_state.left+30, height=60}
  Editor_state = edit.initialize_test_state()
  Editor_state.lines = load_array{'abc', 'def'}
  Text.redraw_all(Editor_state)
  Editor_state.cursor1 = {line=2, pos=1}
  -- backspace joins with previous line
  edit.run_after_keychord(Editor_state, 'backspace')
  check_eq(Editor_state.lines[1].data, 'abcdef', "F - test_backspace_past_line_boundary")
end

-- some tests for operating over selections created using Shift- chords
-- we're just testing delete_selection, and it works the same for all keys

function test_backspace_over_selection()
  io.write('\ntest_backspace_over_selection')
  -- select just one character within a line with cursor before selection
  App.screen.init{width=Editor_state.left+30, height=60}
  Editor_state = edit.initialize_test_state()
  Editor_state.lines = load_array{'abc', 'def', 'ghi', 'jkl', 'mno'}
  Text.redraw_all(Editor_state)
  Editor_state.cursor1 = {line=1, pos=1}
  Editor_state.selection1 = {line=1, pos=2}
  -- backspace deletes the selected character, even though it's after the cursor
  edit.run_after_keychord(Editor_state, 'backspace')
  check_eq(Editor_state.lines[1].data, 'bc', "F - test_backspace_over_selection/data")
  -- cursor (remains) at start of selection
  check_eq(Editor_state.cursor1.line, 1, "F - test_backspace_over_selection/cursor:line")
  check_eq(Editor_state.cursor1.pos, 1, "F - test_backspace_over_selection/cursor:pos")
  -- selection is cleared
  check_nil(Editor_state.selection1.line, "F - test_backspace_over_selection/selection")
end

function test_backspace_over_selection_reverse()
  io.write('\ntest_backspace_over_selection_reverse')
  -- select just one character within a line with cursor after selection
  App.screen.init{width=Editor_state.left+30, height=60}
  Editor_state = edit.initialize_test_state()
  Editor_state.lines = load_array{'abc', 'def', 'ghi', 'jkl', 'mno'}
  Text.redraw_all(Editor_state)
  Editor_state.cursor1 = {line=1, pos=2}
  Editor_state.selection1 = {line=1, pos=1}
  -- backspace deletes the selected character
  edit.run_after_keychord(Editor_state, 'backspace')
  check_eq(Editor_state.lines[1].data, 'bc', "F - test_backspace_over_selection_reverse/data")
  -- cursor moves to start of selection
  check_eq(Editor_state.cursor1.line, 1, "F - test_backspace_over_selection_reverse/cursor:line")
  check_eq(Editor_state.cursor1.pos, 1, "F - test_backspace_over_selection_reverse/cursor:pos")
  -- selection is cleared
  check_nil(Editor_state.selection1.line, "F - test_backspace_over_selection_reverse/selection")
end

function test_backspace_over_multiple_lines()
  io.write('\ntest_backspace_over_multiple_lines')
  -- select just one character within a line with cursor after selection
  App.screen.init{width=Editor_state.left+30, height=60}
  Editor_state = edit.initialize_test_state()
  Editor_state.lines = load_array{'abc', 'def', 'ghi', 'jkl', 'mno'}
  Text.redraw_all(Editor_state)
  Editor_state.cursor1 = {line=1, pos=2}
  Editor_state.selection1 = {line=4, pos=2}
  -- backspace deletes the region and joins the remaining portions of lines on either side
  edit.run_after_keychord(Editor_state, 'backspace')
  check_eq(Editor_state.lines[1].data, 'akl', "F - test_backspace_over_multiple_lines/data:1")
  check_eq(Editor_state.lines[2].data, 'mno', "F - test_backspace_over_multiple_lines/data:2")
  -- cursor remains at start of selection
  check_eq(Editor_state.cursor1.line, 1, "F - test_backspace_over_multiple_lines/cursor:line")
  check_eq(Editor_state.cursor1.pos, 2, "F - test_backspace_over_multiple_lines/cursor:pos")
  -- selection is cleared
  check_nil(Editor_state.selection1.line, "F - test_backspace_over_multiple_lines/selection")
end

function test_backspace_to_end_of_line()
  io.write('\ntest_backspace_to_end_of_line')
  -- select region from cursor to end of line
  App.screen.init{width=Editor_state.left+30, height=60}
  Editor_state = edit.initialize_test_state()
  Editor_state.lines = load_array{'abc', 'def', 'ghi', 'jkl', 'mno'}
  Text.redraw_all(Editor_state)
  Editor_state.cursor1 = {line=1, pos=2}
  Editor_state.selection1 = {line=1, pos=4}
  -- backspace deletes rest of line without joining to any other line
  edit.run_after_keychord(Editor_state, 'backspace')
  check_eq(Editor_state.lines[1].data, 'a', "F - test_backspace_to_start_of_line/data:1")
  check_eq(Editor_state.lines[2].data, 'def', "F - test_backspace_to_start_of_line/data:2")
  -- cursor remains at start of selection
  check_eq(Editor_state.cursor1.line, 1, "F - test_backspace_to_start_of_line/cursor:line")
  check_eq(Editor_state.cursor1.pos, 2, "F - test_backspace_to_start_of_line/cursor:pos")
  -- selection is cleared
  check_nil(Editor_state.selection1.line, "F - test_backspace_to_start_of_line/selection")
end

function test_backspace_to_start_of_line()
  io.write('\ntest_backspace_to_start_of_line')
  -- select region from cursor to start of line
  App.screen.init{width=Editor_state.left+30, height=60}
  Editor_state = edit.initialize_test_state()
  Editor_state.lines = load_array{'abc', 'def', 'ghi', 'jkl', 'mno'}
  Text.redraw_all(Editor_state)
  Editor_state.cursor1 = {line=2, pos=1}
  Editor_state.selection1 = {line=2, pos=3}
  -- backspace deletes beginning of line without joining to any other line
  edit.run_after_keychord(Editor_state, 'backspace')
  check_eq(Editor_state.lines[1].data, 'abc', "F - test_backspace_to_start_of_line/data:1")
  check_eq(Editor_state.lines[2].data, 'f', "F - test_backspace_to_start_of_line/data:2")
  -- cursor remains at start of selection
  check_eq(Editor_state.cursor1.line, 2, "F - test_backspace_to_start_of_line/cursor:line")
  check_eq(Editor_state.cursor1.pos, 1, "F - test_backspace_to_start_of_line/cursor:pos")
  -- selection is cleared
  check_nil(Editor_state.selection1.line, "F - test_backspace_to_start_of_line/selection")
end

function test_undo_insert_text()
  io.write('\ntest_undo_insert_text')
  App.screen.init{width=120, height=60}
  Editor_state = edit.initialize_test_state()
  Editor_state.lines = load_array{'abc', 'def', 'xyz'}
  Text.redraw_all(Editor_state)
  Editor_state.cursor1 = {line=2, pos=4}
  Editor_state.screen_top1 = {line=1, pos=1}
  Editor_state.screen_bottom1 = {}
  -- insert a character
  edit.draw(Editor_state)
  edit.run_after_textinput(Editor_state, 'g')
  check_eq(Editor_state.cursor1.line, 2, 'F - test_undo_insert_text/baseline/cursor:line')
  check_eq(Editor_state.cursor1.pos, 5, 'F - test_undo_insert_text/baseline/cursor:pos')
  check_nil(Editor_state.selection1.line, 'F - test_undo_insert_text/baseline/selection:line')
  check_nil(Editor_state.selection1.pos, 'F - test_undo_insert_text/baseline/selection:pos')
  local y = Editor_state.top
  App.screen.check(y, 'abc', 'F - test_undo_insert_text/baseline/screen:1')
  y = y + Editor_state.line_height
  App.screen.check(y, 'defg', 'F - test_undo_insert_text/baseline/screen:2')
  y = y + Editor_state.line_height
  App.screen.check(y, 'xyz', 'F - test_undo_insert_text/baseline/screen:3')
  -- undo
  edit.run_after_keychord(Editor_state, 'C-z')
  check_eq(Editor_state.cursor1.line, 2, 'F - test_undo_insert_text/cursor:line')
  check_eq(Editor_state.cursor1.pos, 4, 'F - test_undo_insert_text/cursor:pos')
  check_nil(Editor_state.selection1.line, 'F - test_undo_insert_text/selection:line')
  check_nil(Editor_state.selection1.pos, 'F - test_undo_insert_text/selection:pos')
  y = Editor_state.top
  App.screen.check(y, 'abc', 'F - test_undo_insert_text/screen:1')
  y = y + Editor_state.line_height
  App.screen.check(y, 'def', 'F - test_undo_insert_text/screen:2')
  y = y + Editor_state.line_height
  App.screen.check(y, 'xyz', 'F - test_undo_insert_text/screen:3')
end

function test_undo_delete_text()
  io.write('\ntest_undo_delete_text')
  App.screen.init{width=120, height=60}
  Editor_state = edit.initialize_test_state()
  Editor_state.lines = load_array{'abc', 'defg', 'xyz'}
  Text.redraw_all(Editor_state)
  Editor_state.cursor1 = {line=2, pos=5}
  Editor_state.screen_top1 = {line=1, pos=1}
  Editor_state.screen_bottom1 = {}
  -- delete a character
  edit.run_after_keychord(Editor_state, 'backspace')
  check_eq(Editor_state.cursor1.line, 2, 'F - test_undo_delete_text/baseline/cursor:line')
  check_eq(Editor_state.cursor1.pos, 4, 'F - test_undo_delete_text/baseline/cursor:pos')
  check_nil(Editor_state.selection1.line, 'F - test_undo_delete_text/baseline/selection:line')
  check_nil(Editor_state.selection1.pos, 'F - test_undo_delete_text/baseline/selection:pos')
  local y = Editor_state.top
  App.screen.check(y, 'abc', 'F - test_undo_delete_text/baseline/screen:1')
  y = y + Editor_state.line_height
  App.screen.check(y, 'def', 'F - test_undo_delete_text/baseline/screen:2')
  y = y + Editor_state.line_height
  App.screen.check(y, 'xyz', 'F - test_undo_delete_text/baseline/screen:3')
  -- undo
--?   -- after undo, the backspaced key is selected
  edit.run_after_keychord(Editor_state, 'C-z')
  check_eq(Editor_state.cursor1.line, 2, 'F - test_undo_delete_text/cursor:line')
  check_eq(Editor_state.cursor1.pos, 5, 'F - test_undo_delete_text/cursor:pos')
  check_nil(Editor_state.selection1.line, 'F - test_undo_delete_text/selection:line')
  check_nil(Editor_state.selection1.pos, 'F - test_undo_delete_text/selection:pos')
--?   check_eq(Editor_state.selection1.line, 2, 'F - test_undo_delete_text/selection:line')
--?   check_eq(Editor_state.selection1.pos, 4, 'F - test_undo_delete_text/selection:pos')
  y = Editor_state.top
  App.screen.check(y, 'abc', 'F - test_undo_delete_text/screen:1')
  y = y + Editor_state.line_height
  App.screen.check(y, 'defg', 'F - test_undo_delete_text/screen:2')
  y = y + Editor_state.line_height
  App.screen.check(y, 'xyz', 'F - test_undo_delete_text/screen:3')
end

function test_undo_restores_selection()
  io.write('\ntest_undo_restores_selection')
  -- display a line of text with some part selected
  App.screen.init{width=75, height=80}
  Editor_state = edit.initialize_test_state()
  Editor_state.lines = load_array{'abc'}
  Text.redraw_all(Editor_state)
  Editor_state.cursor1 = {line=1, pos=1}
  Editor_state.selection1 = {line=1, pos=2}
  Editor_state.screen_top1 = {line=1, pos=1}
  Editor_state.screen_bottom1 = {}
  edit.draw(Editor_state)
  -- delete selected text
  edit.run_after_textinput(Editor_state, 'x')
  check_eq(Editor_state.lines[1].data, 'xbc', 'F - test_undo_restores_selection/baseline')
  check_nil(Editor_state.selection1.line, 'F - test_undo_restores_selection/baseline:selection')
  -- undo
  edit.run_after_keychord(Editor_state, 'C-z')
  edit.run_after_keychord(Editor_state, 'C-z')
  -- selection is restored
  check_eq(Editor_state.selection1.line, 1, 'F - test_undo_restores_selection/line')
  check_eq(Editor_state.selection1.pos, 2, 'F - test_undo_restores_selection/pos')
end

function test_search()
  io.write('\ntest_search')
  App.screen.init{width=120, height=60}
  Editor_state = edit.initialize_test_state()
  Editor_state.lines = load_array{'abc', 'def', 'ghi', 'deg'}
  Text.redraw_all(Editor_state)
  Editor_state.cursor1 = {line=1, pos=1}
  Editor_state.screen_top1 = {line=1, pos=1}
  Editor_state.screen_bottom1 = {}
  edit.draw(Editor_state)
  -- search for a string
  edit.run_after_keychord(Editor_state, 'C-f')
  edit.run_after_textinput(Editor_state, 'd')
  edit.run_after_keychord(Editor_state, 'return')
  check_eq(Editor_state.cursor1.line, 2, 'F - test_search/1/cursor:line')
  check_eq(Editor_state.cursor1.pos, 1, 'F - test_search/1/cursor:pos')
  -- reset cursor
  Editor_state.cursor1 = {line=1, pos=1}
  Editor_state.screen_top1 = {line=1, pos=1}
  -- search for second occurrence
  edit.run_after_keychord(Editor_state, 'C-f')
  edit.run_after_textinput(Editor_state, 'de')
  edit.run_after_keychord(Editor_state, 'down')
  edit.run_after_keychord(Editor_state, 'return')
  check_eq(Editor_state.cursor1.line, 4, 'F - test_search/2/cursor:line')
  check_eq(Editor_state.cursor1.pos, 1, 'F - test_search/2/cursor:pos')
end

function test_search_upwards()
  io.write('\ntest_search_upwards')
  App.screen.init{width=120, height=60}
  Editor_state = edit.initialize_test_state()
  Editor_state.lines = load_array{'abc abd'}
  Text.redraw_all(Editor_state)
  Editor_state.cursor1 = {line=1, pos=2}
  Editor_state.screen_top1 = {line=1, pos=1}
  Editor_state.screen_bottom1 = {}
  edit.draw(Editor_state)
  -- search for a string
  edit.run_after_keychord(Editor_state, 'C-f')
  edit.run_after_textinput(Editor_state, 'a')
  -- search for previous occurrence
  edit.run_after_keychord(Editor_state, 'up')
  check_eq(Editor_state.cursor1.line, 1, 'F - test_search_upwards/2/cursor:line')
  check_eq(Editor_state.cursor1.pos, 1, 'F - test_search_upwards/2/cursor:pos')
end

function test_search_wrap()
  io.write('\ntest_search_wrap')
  App.screen.init{width=120, height=60}
  Editor_state = edit.initialize_test_state()
  Editor_state.lines = load_array{'abc'}
  Text.redraw_all(Editor_state)
  Editor_state.cursor1 = {line=1, pos=3}
  Editor_state.screen_top1 = {line=1, pos=1}
  Editor_state.screen_bottom1 = {}
  edit.draw(Editor_state)
  -- search for a string
  edit.run_after_keychord(Editor_state, 'C-f')
  edit.run_after_textinput(Editor_state, 'a')
  edit.run_after_keychord(Editor_state, 'return')
  -- cursor wraps
  check_eq(Editor_state.cursor1.line, 1, 'F - test_search_wrap/1/cursor:line')
  check_eq(Editor_state.cursor1.pos, 1, 'F - test_search_wrap/1/cursor:pos')
end

function test_search_wrap_upwards()
  io.write('\ntest_search_wrap_upwards')
  App.screen.init{width=120, height=60}
  Editor_state = edit.initialize_test_state()
  Editor_state.lines = load_array{'abc abd'}
  Text.redraw_all(Editor_state)
  Editor_state.cursor1 = {line=1, pos=1}
  Editor_state.screen_top1 = {line=1, pos=1}
  Editor_state.screen_bottom1 = {}
  edit.draw(Editor_state)
  -- search upwards for a string
  edit.run_after_keychord(Editor_state, 'C-f')
  edit.run_after_textinput(Editor_state, 'a')
  edit.run_after_keychord(Editor_state, 'up')
  -- cursor wraps
  check_eq(Editor_state.cursor1.line, 1, 'F - test_search_wrap_upwards/1/cursor:line')
  check_eq(Editor_state.cursor1.pos, 5, 'F - test_search_wrap_upwards/1/cursor:pos')
end