Tests for folding. vim: set ft=vim :

STARTTEST
:so small.vim
:" basic test if a fold can be created, opened, moving to the end and closed
/^1
zf2j:call append("$", "manual " . getline(foldclosed(".")))
zo:call append("$", foldclosed("."))
]z:call append("$", getline("."))
zc:call append("$", getline(foldclosed(".")))
:" test folding with markers.
:set fdm=marker fdl=1 fdc=3
/^5
:call append("$", "marker " . foldlevel("."))
[z:call append("$", foldlevel("."))
jo{{ {jj:call append("$", foldlevel("."))
kYpj:call append("$", foldlevel("."))
:" test folding with indent
:set fdm=indent sw=2
/^2 b
i  jI    :call append("$", "indent " . foldlevel("."))
k:call append("$", foldlevel("."))
:" test syntax folding
:set fdm=syntax fdl=0
:syn region Hup start="dd" end="hh" fold
Gzk:call append("$", "folding " . getline("."))
k:call append("$", getline("."))
:" test expression folding
:fun Flvl()
  let l = getline(v:lnum)
  if l =~ "bb$"
    return 2
  elseif l =~ "gg$"
    return "s1"
  elseif l =~ "ii$"
    return ">2"
  elseif l =~ "kk$"
    return "0"
  endif
  return "="
endfun
:set fdm=expr fde=Flvl()
/bb$
:call append("$", "expr " . foldlevel("."))
/hh$
:call append("$", foldlevel("."))
/ii$
:call append("$", foldlevel("."))
/kk$
:call append("$", foldlevel("."))
:/^last/+1,$w! test.out
:qa!
ENDTEST

1 aa
2 bb
3 cc
4 dd {{{
5 ee {{{ }}}
6 ff }}}
7 gg
8 hh
9 ii
a jj
b kk
last
