Execute (Setup):
  colo seoul256

Before:
  unlet! g:limelight_default_coefficient
       \ g:limelight_conceal_guifg g:limelight_conceal_ctermfg

Execute (Invalid argument type):
  Limelight 'hello'
  Assert !exists('#limelight')

  Limelight {}
  Assert !exists('#limelight')

  Limelight []
  Assert !exists('#limelight')

Execute (Invalid argument range):
  Limelight 1.2
  Assert !exists('#limelight')

  Limelight 2
  Assert !exists('#limelight')

  Limelight -0.2
  Assert !exists('#limelight')

  Limelight -1
  Assert !exists('#limelight')

Execute (Limelight / Limelight!):
  Limelight
  Assert exists('#limelight')

  Limelight
  Assert exists('#limelight')

  Limelight!
  Assert !exists('#limelight')

  Limelight!
  Assert !exists('#limelight')

  Limelight 0.5
  Assert exists('#limelight')

  Limelight!
  Assert !exists('#limelight')

Execute (Limelight!!):
  Limelight!!
  Assert exists('#limelight')

  Limelight!!
  Assert !exists('#limelight')

  Limelight!! 2.0
  Assert !exists('#limelight')

  Limelight!! 0.9
  Assert exists('#limelight')

  Limelight!! 0.9
  Assert !exists('#limelight')

Execute (g:limelight_default_coefficient):
  let g:limelight_default_coefficient = 2.0
  Limelight
  Assert !exists('#limelight')

  let g:limelight_default_coefficient = -1.0
  Limelight
  Assert !exists('#limelight')

Execute (Unsupported terminal):
  colo default
  let &t_Co = 16

  Limelight
  Assert !exists('#limelight')

Execute (Unsupported. but g:limelight_conceal_???fg defined):
  if has('gui_running')
    colo default
    let g:limelight_conceal_guifg = '#cccccc'
    Limelight
    Assert exists('#limelight')
    Limelight!
    Assert !exists('#limelight')
  else
    colo default
    let &t_Co = 256
    let g:limelight_conceal_ctermfg = 240

    Limelight
    Assert exists('#limelight')
    Limelight!
    Assert !exists('#limelight')

    let g:limelight_conceal_ctermfg = 'red'

  endif

  " However, you're still not allowed to pass argument to Limelight command
  Limelight 0.5
  Assert !exists('#limelight')