Execute ( SpaceVim api: data#command complete):
  let cmd = SpaceVim#api#import('vim#command')
  let cmd.options = {
    \ '-d' : {
      \ 'complete' : ['foo', 'baa'],
    \ }
    \ }
    AssertEqual cmd.complete('', 'A ', 3), '-d'
    AssertEqual cmd.complete('', 'A -d ', 6), "foo\nbaa"
    AssertEqual cmd.complete('f', 'A -d f', 7), "foo\nbaa"