Describe highlighter.vim
  It should create separator highlight groups
    hi highlighter1 ctermfg=1 ctermbg=2
    hi highlighter2 ctermfg=3 ctermbg=4
    call airline#highlighter#add_separator('highlighter1', 'highlighter2', 0)
    let hl = airline#highlighter#get_highlight('highlighter1_to_highlighter2')
    Assert Equal([ 'NONE', 'NONE', '4', '2', '' ], hl)
  End

  if exists("+termguicolors")
    It should create separator highlight groups with termguicolors
      set termguicolors
      hi highlighter1 guifg=#cd0000 guibg=#00cd00 ctermfg=1 ctermbg=2
      hi highlighter2 guifg=#cdcd00 guibg=#0000ee ctermfg=3 ctermbg=4
      call airline#highlighter#add_separator('highlighter1', 'highlighter2', 0)
      let hl = airline#highlighter#get_highlight('highlighter1_to_highlighter2')
      Assert Equal(['#0000ee', '#00cd00', '4', '2', '' ], hl)
    End
  endif

  It should populate accent colors
    Assert False(exists('g:airline#themes#dark#palette.normal.airline_c_red'))
    call airline#themes#patch(g:airline#themes#dark#palette)
    call airline#highlighter#add_accent('red')
    call airline#highlighter#highlight(['normal'])
    Assert NotEqual(0, hlID('airline_c_red'))
  End
End