Before:
  Save g:ale_max_buffer_history_size
  Save g:ale_history_log_output
  Save g:ale_run_synchronously

  unlet! b:ale_fixers
  unlet! b:ale_enabled
  unlet! b:ale_history

  " Temporarily set the shell to /bin/sh, if it isn't already set that way.
  " This will make it so the test works when running it directly.
  let g:current_shell = &shell

  if !has('win32')
    let &shell = '/bin/sh'
  endif

  let g:history = []
  let g:ale_buffer_info = {}
  let g:ale_max_buffer_history_size = 20
  let g:ale_history_log_output = 0

  function! TestFixer(buffer)
    return {'command': 'echo foo'}
  endfunction

  function! CollectResults(buffer, output)
    return []
  endfunction

  call ale#linter#Define('foobar', {
  \ 'name': 'testlinter',
  \ 'callback': 'CollectResults',
  \ 'executable': has('win32') ? 'cmd' : 'echo',
  \ 'command': has('win32')
  \   ? 'echo command history test'
  \   : '/bin/sh -c ''echo command history test''',
  \ 'read_buffer': 0,
  \})

After:
  Restore

  unlet! b:ale_fixers
  unlet! b:ale_enabled
  " Clear the history we changed.
  unlet! b:ale_history

  " Reset the shell back to what it was before.
  let &shell = g:current_shell
  unlet g:current_shell
  let g:ale_history_enabled = 1
  let g:ale_history_log_output = 0
  unlet g:history
  let g:ale_buffer_info = {}
  let g:ale_max_buffer_history_size = 20
  call ale#linter#Reset()
  delfunction TestFixer
  delfunction CollectResults

Given foobar (Some imaginary filetype):
  anything

Execute(History should be set when commands are run):
  AssertEqual 'foobar', &filetype

  call ale#Lint()
  call ale#engine#WaitForJobs(2000)

  let g:history = filter(
  \ copy(ale#history#Get(bufnr(''))),
  \ 'v:val.job_id isnot# ''executable''',
  \)

  AssertEqual 1, len(g:history)
  AssertEqual sort(['status', 'exit_code', 'job_id', 'command']), sort(keys(g:history[0]))

  if has('win32')
    AssertEqual 'cmd /s/c "echo command history test"', g:history[0].command
  else
    AssertEqual ['/bin/sh', '-c', '/bin/sh -c ''echo command history test'''], g:history[0].command
  endif

  AssertEqual 'finished', g:history[0].status
  AssertEqual 0, g:history[0].exit_code
  " The Job ID will change each time, but we can check the type.
  AssertEqual type(1), type(g:history[0].job_id)

Execute(History should be not set when disabled):
  AssertEqual 'foobar', &filetype

  let g:ale_history_enabled = 0

  call ale#Lint()
  call ale#engine#WaitForJobs(2000)

  AssertEqual [], ale#history#Get(bufnr(''))

Execute(History should include command output if logging is enabled):
  AssertEqual 'foobar', &filetype

  let g:ale_history_log_output = 1

  call ale#Lint()
  call ale#engine#WaitForJobs(2000)

  let g:history = ale#history#Get(bufnr(''))

  AssertEqual 1, len(g:history)
  AssertEqual ['command history test'], g:history[0].output

Execute(History items should be popped after going over the max):
  let b:ale_history = map(range(20), '{''status'': ''started'', ''job_id'': v:val, ''command'': ''foobar''}')

  call ale#history#Add(bufnr(''), 'started', 347, 'last command')

  AssertEqual
  \ (
  \   map(range(1, 19), '{''status'': ''started'', ''job_id'': v:val, ''command'': ''foobar''}')
  \   + [{'status': 'started', 'job_id': 347, 'command': 'last command'}]
  \ ),
  \ ale#history#Get(bufnr(''))

Execute(Nothing should be added to history if the size is too low):
  let g:ale_max_buffer_history_size = 0

  call ale#history#Add(bufnr(''), 'started', 347, 'last command')

  AssertEqual [], ale#history#Get(bufnr(''))

  let g:ale_max_buffer_history_size = -2

  call ale#history#Add(1, 'started', 347, 'last command')

  AssertEqual [], ale#history#Get(bufnr(''))

Given foobar(Some file with an imaginary filetype):
  a
  b
  c

Execute(The history should be updated when fixers are run):
  call ale#test#SetFilename('dummy.txt')

  let b:ale_fixers = {'foobar': ['TestFixer']}
  let b:ale_enabled = 0
  let g:ale_run_synchronously = 1

  ALEFix

  AssertEqual ['finished'], map(copy(b:ale_history), 'v:val.status')

  if has('win32')
    AssertEqual 'cmd /s/c "echo foo ', split(b:ale_history[0].command, '<')[0]
  else
    AssertEqual '/bin/sh -c echo foo ', split(join(b:ale_history[0].command), '<')[0]
  endif