" Command to check for the presence of a feature.
command -nargs=1 CheckFeature call CheckFeature(<f-args>)
func CheckFeature(name)
  if !has(a:name)
    throw 'Skipped: ' .. a:name .. ' feature missing'
  endif
endfunc

" Command to check for the presence of a working option.
command -nargs=1 CheckOption call CheckOption(<f-args>)
func CheckOption(name)
  if !exists('+' .. a:name)
    throw 'Skipped: ' .. a:name .. ' option not supported'
  endif
endfunc

" Command to check for the presence of a function.
command -nargs=1 CheckFunction call CheckFunction(<f-args>)
func CheckFunction(name)
  if !exists('*' .. a:name)
    throw 'Skipped: ' .. a:name .. ' function missing'
  endif
endfunc

" Command to check for the presence of an Ex command
command -nargs=1 CheckCommand call CheckCommand(<f-args>)
func CheckCommand(name)
  if !exists(':' .. a:name)
    throw 'Skipped: ' .. a:name .. ' command not supported'
  endif
endfunc

" Command to check for the presence of a shell command
command -nargs=1 CheckExecutable call CheckExecutable(<f-args>)
func CheckExecutable(name)
  if !executable(a:name)
    throw 'Skipped: ' .. a:name .. ' program not executable'
  endif
endfunc

" Command to check for running on MS-Windows
command CheckMSWindows call CheckMSWindows()
func CheckMSWindows()
  if !has('win32')
    throw 'Skipped: only works on MS-Windows'
  endif
endfunc

" Command to check for NOT running on MS-Windows
command CheckNotMSWindows call CheckNotMSWindows()
func CheckNotMSWindows()
  if has('win32')
    throw 'Skipped: does not work on MS-Windows'
  endif
endfunc

" Command to check for running on Unix
command CheckUnix call CheckUnix()
func CheckUnix()
  if !has('unix')
    throw 'Skipped: only works on Unix'
  endif
endfunc

" Command to check that making screendumps is supported.
" Caller must source screendump.vim
command CheckScreendump call CheckScreendump()
func CheckScreendump()
  if !CanRunVimInTerminal()
    throw 'Skipped: cannot make screendumps'
  endif
endfunc

" Command to check that we can Run Vim in a terminal window
command CheckRunVimInTerminal call CheckRunVimInTerminal()
func CheckRunVimInTerminal()
  if !CanRunVimInTerminal()
    throw 'Skipped: cannot run Vim in a terminal window'
  endif
endfunc

" Command to check that we can run the GUI
command CheckCanRunGui call CheckCanRunGui()
func CheckCanRunGui()
  if !has('gui') || ($DISPLAY == "" && !has('gui_running'))
    throw 'Skipped: cannot start the GUI'
  endif
endfunc

" Command to check that we are using the GUI
command CheckGui call CheckGui()
func CheckGui()
  if !has('gui_running')
    throw 'Skipped: only works in the GUI'
  endif
endfunc

" Command to check that not currently using the GUI
command CheckNotGui call CheckNotGui()
func CheckNotGui()
  if has('gui_running')
    throw 'Skipped: only works in the terminal'
  endif
endfunc
