== Summary of tests for the text editor

This doesn't include all tests and might not change between forks, but it's
intended to be the "timeless core" of a text editor widget that shouldn't
change across forks.

# basic
initial state
draw text
draw wrapping text
draw word wrapping text
draw text wrapping within word
draw wrapping text containing non ascii

# mouse
click moves cursor
click to left of line
click takes margins into account
click on empty line
click on wrapping line
click on wrapping line takes margins into account
click on wrapping line
click on wrapping line rendered from partway at top of screen
click past end of wrapping line
click past end of wrapping line containing non ascii
click past end of word wrapping line

# cursor movement
move left
  move left to previous line
move right
  move right to next line

move to start of word
  move to start of previous word
  move to start of word on previous line
move past end of word
  move past end of word on next line
skip to previous word
  skip past tab to previous word
  skip multiple spaces to previous word
skip to next word
  skip past tab to next word
  skip multiple spaces to next word

# mutating text
insert first character
edit wrapping text
insert newline
insert newline at start of line
insert from clipboard
backspace from start of final line
backspace past line boundary
backspace over selection
backspace over selection reverse
backspace over multiple lines
backspace to end of line
backspace to start of line

# scroll
pagedown
pagedown often shows start of wrapping line
pagedown can start from middle of long wrapping line
pagedown never moves up
down arrow moves cursor
down arrow scrolls down by one line
down arrow scrolls down by one screen line
down arrow scrolls down by one screen line after splitting within word
pagedown followed by down arrow does not scroll screen up
up arrow moves cursor
up arrow scrolls up by one line
up arrow scrolls up by one screen line
up arrow scrolls up to final screen line
up arrow scrolls up to empty line
pageup
pageup scrolls up by screen line
pageup scrolls up from middle screen line
enter on bottom line scrolls down
enter on final line avoids scrolling down when not at bottom
inserting text on final line avoids scrolling down when not at bottom
typing on bottom line scrolls down
left arrow scrolls up in wrapped line
right arrow scrolls down in wrapped line
home scrolls up in wrapped line
end scrolls down in wrapped line
position cursor on recently edited wrapping line
backspace can scroll up
backspace can scroll up screen line

# selection
select text using shift and cursor movement operations
select text using mouse
  clicking to left of a line = start of line
  clicking to right of a line = end of line
  clicking above topmost line = top of screen
  clicking below bottom-most line = bottom of screen
select text using mouse and shift
select text repeatedly using mouse and shift
cursor movement without shift resets selection
mouse click without shift resets selection
edit deletes selection
edit with shift key deletes selection
deleting selection may scroll
copy does not reset selection
cut
cut without selection
paste replaces selection

# search
search
search upwards
search wrap
search wrap upwards

# undo
undo insert text
undo delete text
undo restores selection