Before:
  Save g:ale_set_loclist
  Save g:ale_set_quickfix
  Save g:ale_loclist_msg_format
  Save g:ale_open_list
  Save g:ale_buffer_info
  Save g:ale_set_lists_synchronously

  let g:ale_set_lists_synchronously = 1
  let g:ale_loclist_msg_format = '%code: %%s'
  let g:ale_open_list = 0
  let g:loclist = []
  let g:ale_buffer_info = {bufnr(''): {'loclist': g:loclist}}

  function! AddItem(data) abort
    let l:item = {
    \ 'bufnr': bufnr(''),
    \ 'lnum': 1,
    \ 'col': 1,
    \ 'type': 'E',
    \ 'linter_name': 'some_linter',
    \}

    call add(g:loclist, extend(l:item, a:data))
  endfunction

After:
  Restore

  unlet! g:loclist
  unlet! b:ale_loclist_msg_format

  delfunction AddItem

  call setloclist(0, [])
  call setqflist([])

Execute(Formatting with codes should work for the loclist):
  call AddItem({'text': "nocode\r"})
  call ale#list#SetLists(bufnr(''), g:loclist)

  AssertEqual
  \ [
  \   {
  \     'lnum': 1,
  \     'bufnr': bufnr(''),
  \     'col': 1,
  \     'valid': 1,
  \     'vcol': 0,
  \     'nr': 0,
  \     'type': 'E',
  \     'pattern': '',
  \     'text': 'nocode',
  \   },
  \ ],
  \ ale#test#GetLoclistWithoutNewerKeys()

  call remove(g:loclist, 0)
  call AddItem({'text': 'withcode', 'code': 'E123'})
  call ale#list#SetLists(bufnr(''), g:loclist)

  AssertEqual
  \ [
  \   {
  \     'lnum': 1,
  \     'bufnr': bufnr(''),
  \     'col': 1,
  \     'valid': 1,
  \     'vcol': 0,
  \     'nr': 0,
  \     'type': 'E',
  \     'pattern': '',
  \     'text': 'E123: withcode',
  \   },
  \ ],
  \ ale#test#GetLoclistWithoutNewerKeys()

Execute(Formatting with codes should work for the quickfix list):
  let g:ale_set_loclist = 0
  let g:ale_set_quickfix = 1

  call AddItem({'text': "nocode\r"})
  call ale#list#SetLists(bufnr(''), g:loclist)

  AssertEqual
  \ [
  \   {
  \     'lnum': 1,
  \     'bufnr': bufnr(''),
  \     'col': 1,
  \     'valid': 1,
  \     'vcol': 0,
  \     'nr': 0,
  \     'type': 'E',
  \     'pattern': '',
  \     'text': 'nocode',
  \   },
  \ ],
  \ ale#test#GetQflistWithoutNewerKeys()

  call remove(g:loclist, 0)
  call AddItem({'text': 'withcode', 'code': 'E123'})
  call ale#list#SetLists(bufnr(''), g:loclist)

  AssertEqual
  \ [
  \   {
  \     'lnum': 1,
  \     'bufnr': bufnr(''),
  \     'col': 1,
  \     'valid': 1,
  \     'vcol': 0,
  \     'nr': 0,
  \     'type': 'E',
  \     'pattern': '',
  \     'text': 'E123: withcode',
  \   },
  \ ],
  \ ale#test#GetQflistWithoutNewerKeys()

Execute(Formatting with the linter name should work for the loclist):
  let g:ale_loclist_msg_format = '(%linter%) %s'

  call AddItem({'text': 'whatever'})
  call ale#list#SetLists(bufnr(''), g:loclist)

  AssertEqual
  \ [
  \   {
  \     'lnum': 1,
  \     'bufnr': bufnr(''),
  \     'col': 1,
  \     'valid': 1,
  \     'vcol': 0,
  \     'nr': 0,
  \     'type': 'E',
  \     'pattern': '',
  \     'text': '(some_linter) whatever',
  \   },
  \ ],
  \ ale#test#GetLoclistWithoutNewerKeys()

Execute(Formatting with the linter name should work for the quickfix list):
  let g:ale_loclist_msg_format = '(%linter%) %s'
  let g:ale_set_loclist = 0
  let g:ale_set_quickfix = 1

  call AddItem({'text': 'whatever'})
  call ale#list#SetLists(bufnr(''), g:loclist)

  AssertEqual
  \ [
  \   {
  \     'lnum': 1,
  \     'bufnr': bufnr(''),
  \     'col': 1,
  \     'valid': 1,
  \     'vcol': 0,
  \     'nr': 0,
  \     'type': 'E',
  \     'pattern': '',
  \     'text': '(some_linter) whatever',
  \   },
  \ ],
  \ ale#test#GetQflistWithoutNewerKeys()

Execute(The buffer loclist format option should take precedence):
  let g:ale_loclist_msg_format = '(%linter%) %s'
  let b:ale_loclist_msg_format = 'FOO %s'

  call AddItem({'text': 'whatever'})
  call ale#list#SetLists(bufnr(''), g:loclist)

  AssertEqual
  \ [
  \   {
  \     'lnum': 1,
  \     'bufnr': bufnr(''),
  \     'col': 1,
  \     'valid': 1,
  \     'vcol': 0,
  \     'nr': 0,
  \     'type': 'E',
  \     'pattern': '',
  \     'text': 'FOO whatever',
  \   },
  \ ],
  \ ale#test#GetLoclistWithoutNewerKeys()