neovim/src/nvim/testdir/test_diffmode.vim

" Tests for diff mode

func Test_diff_fold_sync()
  enew!
  let l = range(50)
  call setline(1, l)
  diffthis
  let winone = win_getid()
  new
  let l[25] = 'diff'
  call setline(1, l)
  diffthis
  let wintwo = win_getid()
  " line 15 is inside the closed fold
  call assert_equal(19, foldclosedend(10))
  call win_gotoid(winone)
  call assert_equal(19, foldclosedend(10))
  " open the fold
  normal zv
  call assert_equal(-1, foldclosedend(10))
  " fold in other window must have opened too
  call win_gotoid(wintwo)
  call assert_equal(-1, foldclosedend(10))

  " cursor position is in sync
  normal 23G
  call win_gotoid(winone)
  call assert_equal(23, getcurpos()[1])

  windo diffoff
  close!
  set nomodified
endfunc

func Test_vert_split()
  " Disable the title to avoid xterm keeping the wrong one.
  set notitle noicon
  new
  let l = ['1 aa', '2 bb', '3 cc', '4 dd', '5 ee']
  call setline(1, l)
  w! Xtest
  normal dd
  $
  put
  normal kkrXoxxx
  w! Xtest2
  file Nop
  normal ggoyyyjjjozzzz
  set foldmethod=marker foldcolumn=4
  call assert_equal(0, &diff)
  call assert_equal('marker', &foldmethod)
  call assert_equal(4, &foldcolumn)
  call assert_equal(0, &scrollbind)
  call assert_equal(0, &cursorbind)
  call assert_equal(1, &wrap)

  vert diffsplit Xtest
  vert diffsplit Xtest2
  call assert_equal(1, &diff)
  call assert_equal('diff', &foldmethod)
  call assert_equal(2, &foldcolumn)
  call assert_equal(1, &scrollbind)
  call assert_equal(1, &cursorbind)
  call assert_equal(0, &wrap)

  let diff_fdm = &fdm
  let diff_fdc = &fdc
  " repeat entering diff mode here to see if this saves the wrong settings
  diffthis
  " jump to second window for a moment to have filler line appear at start of
  " first window
  wincmd w
  normal gg
  wincmd p
  normal gg
  call assert_equal(2, winline())
  normal j
  call assert_equal(4, winline())
  normal j
  call assert_equal(5, winline())
  normal j
  call assert_equal(6, winline())
  normal j
  call assert_equal(8, winline())
  normal j
  call assert_equal(9, winline())

  wincmd w
  normal gg
  call assert_equal(1, winline())
  normal j
  call assert_equal(2, winline())
  normal j
  call assert_equal(4, winline())
  normal j
  call assert_equal(5, winline())
  normal j
  call assert_equal(8, winline())

  wincmd w
  normal gg
  call assert_equal(2, winline())
  normal j
  call assert_equal(3, winline())
  normal j
  call assert_equal(4, winline())
  normal j
  call assert_equal(5, winline())
  normal j
  call assert_equal(6, winline())
  normal j
  call assert_equal(7, winline())
  normal j
  call assert_equal(8, winline())

  " Test diffoff
  diffoff!
  1wincmd 2
  let &diff = 1
  let &fdm = diff_fdm
  let &fdc = diff_fdc
  4wincmd w
  diffoff!
  1wincmd w
  call assert_equal(0, &diff)
  call assert_equal('marker', &foldmethod)
  call assert_equal(4, &foldcolumn)
  call assert_equal(0, &scrollbind)
  call assert_equal(0, &cursorbind)
  call assert_equal(1, &wrap)

  wincmd w
  call assert_equal(0, &diff)
  call assert_equal('marker', &foldmethod)
  call assert_equal(4, &foldcolumn)
  call assert_equal(0, &scrollbind)
  call assert_equal(0, &cursorbind)
  call assert_equal(1, &wrap)

  wincmd w
  call assert_equal(0, &diff)
  call assert_equal('marker', &foldmethod)
  call assert_equal(4, &foldcolumn)
  call assert_equal(0, &scrollbind)
  call assert_equal(0, &cursorbind)
  call assert_equal(1, &wrap)

  call delete('Xtest')
  call delete('Xtest2')
  windo bw!
endfunc

func Test_filler_lines()
  " Test that diffing shows correct filler lines
  enew!
  put =range(4,10)
  1d _
  vnew
  put =range(1,10)
  1d _
  windo diffthis
  wincmd h
  call assert_equal(1, line('w0'))
  unlet! diff_fdm diff_fdc
  windo diffoff
  bwipe!
  enew!
endfunc

func Test_diffget_diffput()
  enew!
  let l = range(50)
  call setline(1, l)
  call assert_fails('diffget', 'E99:')
  diffthis
  call assert_fails('diffget', 'E100:')
  new
  let l[10] = 'one'
  let l[20] = 'two'
  let l[30] = 'three'
  let l[40] = 'four'
  call setline(1, l)
  diffthis
  call assert_equal('one', getline(11))
  11diffget
  call assert_equal('10', getline(11))
  21diffput
  wincmd w
  call assert_equal('two', getline(21))
  normal 31Gdo
  call assert_equal('three', getline(31))
  call assert_equal('40', getline(41))
  normal 41Gdp
  wincmd w
  call assert_equal('40', getline(41))
  new
  diffthis
  call assert_fails('diffget', 'E101:')

  windo diffoff
  bwipe!
  bwipe!
  enew!
endfunc