Before:
  let g:can_run_socket_tests = !has('win32')
  \ && (exists('*ch_close') || exists('*chanclose'))

  if g:can_run_socket_tests
    call ale#test#SetDirectory('/testplugin/test')

    let g:channel_id_received = 0
    let g:data_received = ''

    function! WaitForData(expected_data, timeout) abort
      let l:ticks = 0

      while l:ticks < a:timeout
        " Sleep first, so we can switch to the callback.
        let l:ticks += 10
        sleep 10ms

        if g:data_received is# a:expected_data
          break
        endif
      endwhile
    endfunction

    function! TestCallback(channel_id, data) abort
      let g:channel_id_received = a:channel_id
      let g:data_received .= a:data
    endfunction

    let g:port = 10347
    let g:pid_tcp = str2nr(system(
    \ 'python'
    \ . ' ' . ale#Escape(g:dir . '/script/dumb_tcp_server.py')
    \ . ' ' . g:port
    \))
    let g:pipe_path = tempname()
    let g:pid_pipe = str2nr(system(
    \ 'python'
    \ . ' ' . ale#Escape(g:dir . '/script/dumb_named_pipe_server.py')
    \ . ' ' . g:pipe_path
    \))
  endif

After:
  if g:can_run_socket_tests
    call ale#test#RestoreDirectory()

    unlet! g:channel_id_received
    unlet! g:data_received
    unlet! g:channel_id

    delfunction WaitForData
    delfunction TestCallback

    if has_key(g:, 'pid_tcp')
      call system('kill ' . g:pid_tcp)
    endif

    if has_key(g:, 'pid_pipe')
      call system('kill ' . g:pid_pipe)
    endif

    unlet! g:pid_tcp
    unlet! g:port
    unlet! g:pid_pipe
    unlet! g:pipe_path
  endif

  unlet! g:can_run_socket_tests

Execute(Sending and receiving connections to tcp sockets should work):
  if g:can_run_socket_tests
    let g:channel_id = ale#socket#Open(
    \ '127.0.0.1:' . g:port,
    \ {'callback': function('TestCallback')}
    \)

    Assert g:channel_id >= 0, 'The socket was not opened!'

    call ale#socket#Send(g:channel_id, 'hello')
    call ale#socket#Send(g:channel_id, ' world')

    AssertEqual 1, ale#socket#IsOpen(g:channel_id)

    " Wait up to 1 second for the expected data to arrive.
    call WaitForData('hello world', 1000)

    AssertEqual g:channel_id, g:channel_id_received
    AssertEqual 'hello world', g:data_received
    AssertEqual '127.0.0.1:' . g:port, ale#socket#GetAddress(g:channel_id)

    call ale#socket#Close(g:channel_id)

    AssertEqual 0, ale#socket#IsOpen(g:channel_id)
    AssertEqual '', ale#socket#GetAddress(g:channel_id)
  endif

  " NeoVim versions which can't connect to sockets should just fail.
  if has('nvim') && !exists('*chanclose')
    AssertEqual -1, ale#socket#Open(
    \ '127.0.0.1:1111',
    \ {'callback': function('function')}
    \)
  endif

Execute(Sending and receiving connections to named pipe sockets should work):
  if g:can_run_socket_tests && has('nvim-0.4')
    let g:channel_id = ale#socket#Open(
    \ g:pipe_path,
    \ {'callback': function('TestCallback')}
    \)

    Assert g:channel_id >= 0, 'The socket was not opened!'

    call ale#socket#Send(g:channel_id, 'hello')
    call ale#socket#Send(g:channel_id, ' world')

    AssertEqual 1, ale#socket#IsOpen(g:channel_id)

    " Wait up to 1 second for the expected data to arrive.
    call WaitForData('hello world', 1000)

    AssertEqual g:channel_id, g:channel_id_received
    AssertEqual 'hello world', g:data_received
    AssertEqual g:pipe_path, ale#socket#GetAddress(g:channel_id)

    call ale#socket#Close(g:channel_id)

    AssertEqual 0, ale#socket#IsOpen(g:channel_id)
    AssertEqual '', ale#socket#GetAddress(g:channel_id)
  endif

  " NeoVim versions which can't connect to sockets should just fail.
  if has('nvim-0.4') && !exists('*chanclose')
    AssertEqual -1, ale#socket#Open(
    \ g:pipe_path,
    \ {'callback': function('function')}
    \)
  endif