Before:
  Save g:ale_run_synchronously
  Save g:ale_buffer_info
  Save g:ale_linters

  let g:ale_buffer_info = {}
  let g:ale_run_synchronously = 1
  call ale#ResetLintFileMarkers()

  let g:buffer_result = [
  \ {
  \   'lnum': 1,
  \   'col': 1,
  \   'text': 'buffer error',
  \   'type': 'E',
  \ },
  \ {
  \   'lnum': 2,
  \   'col': 1,
  \   'text': 'buffer warning',
  \   'type': 'W',
  \ },
  \]

  function! LintFileCallback(buffer, output)
    return [
    \ {
    \   'lnum': 1,
    \   'col': 3,
    \   'text': 'file warning',
    \   'type': 'W',
    \ },
    \ {
    \   'lnum': 2,
    \   'col': 3,
    \   'text': 'file error',
    \   'type': 'E',
    \ },
    \]
  endfunction

  function! BufferCallback(buffer, output)
    return deepcopy(g:buffer_result)
  endfunction

  function! GetSimplerLoclist()
    let l:loclist = []

    for l:item in getloclist(0)
      call add(l:loclist, {
      \ 'lnum': l:item.lnum,
      \ 'col': l:item.col,
      \ 'text': l:item.text,
      \ 'type': l:item.type,
      \})
    endfor

    return l:loclist
  endfunction

  call ale#linter#Define('foobar', {
  \ 'name': 'lint_file_linter',
  \ 'callback': 'LintFileCallback',
  \ 'executable': 'echo',
  \ 'command': 'echo',
  \ 'lint_file': 1,
  \})

  call ale#linter#Define('foobar', {
  \ 'name': 'buffer_linter',
  \ 'callback': 'BufferCallback',
  \ 'executable': 'echo',
  \ 'command': 'echo',
  \ 'read_buffer': 0,
  \})

  let g:filename = tempname()
  call writefile([], g:filename)
  call ale#test#SetFilename(g:filename)

After:
  Restore

  unlet g:buffer_result
  let g:ale_buffer_info = {}
  call ale#linter#Reset()
  call setloclist(0, [])
  delfunction LintFileCallback
  delfunction BufferCallback

  if filereadable(g:filename)
    call delete(g:filename)
  endif

  unlet g:filename

Given foobar (Some imaginary filetype):
  foo
  bar
  baz

Execute(Running linters without 'lint_file' should run only buffer linters):
  call ale#Queue(0)

  AssertEqual [
  \ {
  \   'lnum': 1,
  \   'col': 1,
  \   'text': 'buffer error',
  \   'type': 'E',
  \ },
  \ {
  \   'lnum': 2,
  \   'col': 1,
  \   'text': 'buffer warning',
  \   'type': 'W',
  \ },
  \], GetSimplerLoclist()

Execute(Running linters with 'lint_file' should run all linters):
  Assert filereadable(expand('%:p')), 'The file was not readable'

  call ale#Queue(0, 'lint_file')

  AssertEqual [
  \ {
  \   'lnum': 1,
  \   'col': 1,
  \   'text': 'buffer error',
  \   'type': 'E',
  \ },
  \ {
  \   'lnum': 1,
  \   'col': 3,
  \   'text': 'file warning',
  \   'type': 'W',
  \ },
  \ {
  \   'lnum': 2,
  \   'col': 1,
  \   'text': 'buffer warning',
  \   'type': 'W',
  \ },
  \ {
  \   'lnum': 2,
  \   'col': 3,
  \   'text': 'file error',
  \   'type': 'E',
  \ },
  \], GetSimplerLoclist()

Execute(Linter errors from files should be kept):
  Assert filereadable(expand('%:p')), 'The file was not readable'

  call ale#Queue(0, 'lint_file')

  " Change the results for the buffer callback.
  let g:buffer_result = [
  \ {
  \   'lnum': 1,
  \   'col': 1,
  \   'text': 'new buffer error',
  \   'type': 'E',
  \ },
  \]

  call ale#Queue(0)

  AssertEqual [
  \ {
  \   'lnum': 1,
  \   'col': 1,
  \   'text': 'new buffer error',
  \   'type': 'E',
  \ },
  \ {
  \   'lnum': 1,
  \   'col': 3,
  \   'text': 'file warning',
  \   'type': 'W',
  \ },
  \ {
  \   'lnum': 2,
  \   'col': 3,
  \   'text': 'file error',
  \   'type': 'E',
  \ },
  \], GetSimplerLoclist()

Execute(Linter errors from files should be kept when no other linters are run):
  let g:ale_linters = {'foobar': ['lint_file_linter']}
  Assert filereadable(expand('%:p')), 'The file was not readable'

  call ale#Queue(0, 'lint_file')

  AssertEqual [
  \ {
  \   'lnum': 1,
  \   'col': 3,
  \   'text': 'file warning',
  \   'type': 'W',
  \ },
  \ {
  \   'lnum': 2,
  \   'col': 3,
  \   'text': 'file error',
  \   'type': 'E',
  \ },
  \], GetSimplerLoclist()

  call ale#Queue(0)

  AssertEqual [
  \ {
  \   'lnum': 1,
  \   'col': 3,
  \   'text': 'file warning',
  \   'type': 'W',
  \ },
  \ {
  \   'lnum': 2,
  \   'col': 3,
  \   'text': 'file error',
  \   'type': 'E',
  \ },
  \], GetSimplerLoclist()