Before:
  Save g:ale_buffer_info
  Save g:ale_echo_cursor
  Save g:ale_enabled
  Save g:ale_run_synchronously
  Save g:ale_set_highlights
  Save g:ale_set_loclist
  Save g:ale_set_quickfix
  Save g:ale_set_signs
  Save g:ale_exclude_highlights
  Save b:ale_exclude_highlights

  runtime autoload/ale/virtualtext.vim
  runtime autoload/ale/highlight.vim

  let g:ale_run_synchronously = 1
  unlet! g:ale_run_synchronously_callbacks
  let g:ale_set_highlights = 1
  let g:ale_set_signs = 1
  let g:ale_buffer_info = {}

  " Disable features we don't need for these tests.
  let g:ale_set_quickfix = 0
  let g:ale_set_loclist = 0
  let g:ale_echo_cursor = 0
  let g:ale_exclude_highlights = []
  let b:ale_exclude_highlights = []

  function! GenerateResults(buffer, output)
    return [
    \ {
    \   'lnum': 1,
    \   'col': 1,
    \   'type': 'E',
    \   'text': 'foo',
    \ },
    \ {
    \   'lnum': 2,
    \   'col': 1,
    \   'type': 'W',
    \   'text': 'bar',
    \ },
    \ {
    \   'lnum': 3,
    \   'col': 5,
    \   'type': 'E',
    \   'text': 'wat',
    \ },
    \]
  endfunction

  let g:has_nvim_highlight = exists('*nvim_buf_add_highlight') && exists('*nvim_buf_clear_namespace')
  let g:nvim_highlight_matches = {}

  function! ale#highlight#nvim_buf_clear_namespace(buffer, ns_id, line_start, line_end) abort
    if a:line_end != -1
      throw 'nvim api behavior not supported'
    endif

    let l:matches = get(g:nvim_highlight_matches, a:buffer, [])
    call filter(
    \ l:matches,
    \ {_, val -> val.pos1[0] < (a:line_start + 1) },
    \)
  endfunction

  function! ale#highlight#nvim_buf_add_highlight(buffer, ns_id, hl_group, line, col_start, col_end) abort
    if a:col_end == -1
      throw 'nvim api behavior not supported'
    endif

    let l:matches = get(g:nvim_highlight_matches, a:buffer, [])
    let g:nvim_highlight_matches[a:buffer] = l:matches

    let l:new_match = {
    \ 'group': a:hl_group,
    \ 'priority': 10,
    \ 'pos1': [a:line + 1, a:col_start + 1, a:col_end - a:col_start],
    \}

    call add(l:matches, l:new_match)
    " sort by line number to emulate getmatches faithfully
    call sort(l:matches, {m1, m2 -> m1.pos1[0] - m2.pos1[0]})
  endfunction

  " We don't care what the IDs are, just that we have some matches.
  " The IDs are generated.
  function! GetMatchesWithoutIDs() abort
    if g:has_nvim_highlight
      return get(g:nvim_highlight_matches, bufnr(''), [])
    else
      let l:list = getmatches()

      for l:item in l:list
        call remove(l:item, 'id')
      endfor

      return l:list
    endif
  endfunction

  function! GetLinkedGroup(grp) abort
    return synIDattr(synIDtrans(hlID(a:grp)), 'name')
  endfunction

  call ale#linter#Define('testft', {
  \ 'name': 'x',
  \ 'executable': has('win32') ? 'cmd': 'echo',
  \ 'command': has('win32') ? 'echo' : '/bin/sh -c ''echo''',
  \ 'callback': 'GenerateResults',
  \})
  highlight link SomeOtherGroup SpellBad

After:
  Restore

  unlet! g:ale_run_synchronously_callbacks
  unlet! g:items
  unlet! b:ale_enabled
  unlet! g:has_nvim_highlight
  unlet! g:nvim_highlight_matches

  delfunction GenerateResults
  call ale#linter#Reset()
  call clearmatches()
  call ale#sign#Clear()
  if has('textprop') && has('popupwin')
    call prop_type_delete('ale')
  endif
  highlight clear SomeOtherGroup

  runtime autoload/ale/highlight.vim

Given testft(A Javscript file with warnings/errors):
  foo
  bar
  baz wat
  line four

" Autoloading virtualtext.vim first should still properly initialize hl-groups
Execute(Loading virtualtext first does not break highlight groups):
  AssertEqual
  \ "SpellBad",
  \ GetLinkedGroup("ALEError")
  AssertEqual
  \ "SpellCap",
  \ GetLinkedGroup("ALEWarning")

Execute(Highlights should be set when a linter runs):
  ALELint
  call ale#test#FlushJobs()

  AssertEqual
  \ [
  \   {'group': 'ALEError', 'priority': 10, 'pos1': [1, 1, 1]},
  \   {'group': 'ALEWarning', 'priority': 10, 'pos1': [2, 1, 1]},
  \   {'group': 'ALEError', 'priority': 10, 'pos1': [3, 5, 1]}
  \ ],
  \ GetMatchesWithoutIDs()

" This test is important for preventing ALE from showing highlights for
" the wrong files.
Execute(Highlights set by ALE should be removed when buffer cleanup is done):
  call ale#engine#InitBufferInfo(bufnr('%'))

  call ale#highlight#SetHighlights(bufnr('%'), [
  \ {'bufnr': bufnr('%'), 'type': 'E', 'lnum': 3, 'col': 2},
  \])

  if !g:has_nvim_highlight
    " This check doesn't work with the new API, for some reason.
    AssertEqual
    \ [{'group': 'ALEError', 'priority': 10, 'pos1': [3, 2, 1]}],
    \ GetMatchesWithoutIDs()
  endif

  call ale#engine#Cleanup(bufnr('%'))

  AssertEqual [], GetMatchesWithoutIDs()

Execute(Highlights should be cleared when buffers are hidden):
  call ale#engine#InitBufferInfo(bufnr('%'))
  " The second item should be ignored, as it has no column infomration.
  let g:ale_buffer_info[bufnr('%')].loclist =  [
  \ {'bufnr': bufnr('%'), 'type': 'E', 'lnum': 3, 'col': 2},
  \ {'bufnr': bufnr('%'), 'type': 'E', 'lnum': 4, 'col': 0},
  \]
  call ale#highlight#SetHighlights(
  \ bufnr('%'),
  \ g:ale_buffer_info[bufnr('%')].loclist
  \)

  AssertEqual 1, len(GetMatchesWithoutIDs()), 'The highlights weren''t initially set!'

  call ale#highlight#BufferHidden(bufnr('%'))

  AssertEqual 0, len(GetMatchesWithoutIDs()), 'The highlights weren''t cleared!'

  call ale#highlight#UpdateHighlights()

  AssertEqual 1, len(GetMatchesWithoutIDs()), 'The highlights weren''t set again!'

Execute(Only ALE highlights should be restored when buffers are restored):
  call ale#engine#InitBufferInfo(bufnr('%'))
  let g:ale_buffer_info[bufnr('%')].loclist =  [
  \ {'bufnr': bufnr('%'), 'type': 'E', 'lnum': 3, 'col': 2},
  \]
  call ale#highlight#SetHighlights(
  \ bufnr('%'),
  \ g:ale_buffer_info[bufnr('%')].loclist
  \)

  call matchaddpos('SomeOtherGroup', [[1, 1, 1]])

  " We should have both highlights.
  if g:has_nvim_highlight
    " When the newer NeoVim API is used, we don't have to worry about
    " other highlights, namespacing is available.
    AssertEqual
    \ [
    \   {'group': 'ALEError', 'priority': 10, 'pos1': [3, 2, 1]},
    \ ],
    \ GetMatchesWithoutIDs()
  else
    AssertEqual
    \ [
    \   {'group': 'ALEError', 'priority': 10, 'pos1': [3, 2, 1]},
    \   {'group': 'SomeOtherGroup', 'priority': 10, 'pos1': [1, 1, 1]},
    \ ],
    \ sort(GetMatchesWithoutIDs(), {m1, m2 -> m1.group < m2.group ? -1 : 1})
  endif

  call ale#highlight#BufferHidden(bufnr('%'))

  " We should remove our highlight, but not the other one.
  if g:has_nvim_highlight
    AssertEqual [], GetMatchesWithoutIDs()
  else
    AssertEqual
    \ [
    \   {'group': 'SomeOtherGroup', 'priority': 10, 'pos1': [1, 1, 1]}
    \ ],
    \ GetMatchesWithoutIDs()
  endif

  call ale#highlight#UpdateHighlights()

  " Our highlight should apper again.
  if g:has_nvim_highlight
    AssertEqual
    \ [
    \   {'group': 'ALEError', 'priority': 10, 'pos1': [3, 2, 1]},
    \ ],
    \ GetMatchesWithoutIDs()
  else
    AssertEqual
    \ [
    \   {'group': 'ALEError', 'priority': 10, 'pos1': [3, 2, 1]},
    \   {'group': 'SomeOtherGroup', 'priority': 10, 'pos1': [1, 1, 1]},
    \ ],
    \ sort(GetMatchesWithoutIDs(), {m1, m2 -> m1.group < m2.group ? -1 : 1})
  endif

Execute(Higlight end columns should set an appropriate size):
  call ale#highlight#SetHighlights(bufnr('%'), [
  \ {'bufnr': bufnr('%'), 'type': 'E', 'lnum': 3, 'col': 2, 'end_col': 5},
  \ {'bufnr': bufnr('%'), 'type': 'W', 'lnum': 4, 'col': 1, 'end_col': 5},
  \])

  AssertEqual
  \ [
  \   {'group': 'ALEError', 'priority': 10, 'pos1': [3, 2, 4]},
  \   {'group': 'ALEWarning', 'priority': 10, 'pos1': [4, 1, 5]},
  \ ],
  \ GetMatchesWithoutIDs()

Execute(Higlight end columns should set an appropriate size):
  call ale#highlight#SetHighlights(bufnr('%'), [
  \ {'bufnr': bufnr('%') - 1, 'type': 'E', 'lnum': 1, 'col': 1},
  \ {'bufnr': bufnr('%'), 'type': 'E', 'lnum': 1, 'col': 1},
  \ {'bufnr': bufnr('%'), 'type': 'E', 'lnum': 2, 'col': 1},
  \ {'bufnr': bufnr('%'), 'type': 'E', 'sub_type': 'style', 'lnum': 3, 'col': 1},
  \ {'bufnr': bufnr('%'), 'type': 'W', 'lnum': 4, 'col': 1},
  \ {'bufnr': bufnr('%'), 'type': 'W', 'lnum': 5, 'col': 1},
  \ {'bufnr': bufnr('%'), 'type': 'W', 'sub_type': 'style', 'lnum': 6, 'col': 1},
  \ {'bufnr': bufnr('%'), 'type': 'I', 'lnum': 7, 'col': 1},
  \ {'bufnr': bufnr('%') + 1, 'type': 'E', 'lnum': 1, 'col': 1},
  \])

  AssertEqual
  \ [
  \   {'group': 'ALEError', 'priority': 10, 'pos1': [1, 1, 1]},
  \   {'group': 'ALEError', 'priority': 10, 'pos1': [2, 1, 1]},
  \   {'group': 'ALEStyleError', 'priority': 10, 'pos1': [3, 1, 1]},
  \   {'group': 'ALEWarning', 'priority': 10, 'pos1': [4, 1, 1]},
  \   {'group': 'ALEWarning', 'priority': 10, 'pos1': [5, 1, 1]},
  \   {'group': 'ALEStyleWarning', 'priority': 10, 'pos1': [6, 1, 1]},
  \   {'group': 'ALEInfo', 'priority': 10, 'pos1': [7, 1, 1]},
  \ ],
  \ GetMatchesWithoutIDs()

Execute(Highlighting should support errors spanning many lines):
  let g:items = [
  \ {'bufnr': bufnr(''), 'type': 'E', 'lnum': 1, 'col': 1, 'end_lnum': 10, 'end_col': 3},
  \]

  call ale#highlight#SetHighlights(bufnr(''), g:items)

  if g:has_nvim_highlight
    " The newer NeoVim highlight API produces different output.
    AssertEqual
    \ [
    \   {'group': 'ALEError', 'priority': 10, 'pos1': [1, 1, 1073741824]},
    \   {'group': 'ALEError', 'priority': 10, 'pos1': [2, 1, 1073741824]},
    \   {'group': 'ALEError', 'priority': 10, 'pos1': [3, 1, 1073741824]},
    \   {'group': 'ALEError', 'priority': 10, 'pos1': [4, 1, 1073741824]},
    \   {'group': 'ALEError', 'priority': 10, 'pos1': [5, 1, 1073741824]},
    \   {'group': 'ALEError', 'priority': 10, 'pos1': [6, 1, 1073741824]},
    \   {'group': 'ALEError', 'priority': 10, 'pos1': [7, 1, 1073741824]},
    \   {'group': 'ALEError', 'priority': 10, 'pos1': [8, 1, 1073741824]},
    \   {'group': 'ALEError', 'priority': 10, 'pos1': [9, 1, 1073741824]},
    \   {'group': 'ALEError', 'priority': 10, 'pos1': [10, 1, 3]},
    \ ],
    \ GetMatchesWithoutIDs()
  else
    " We should set 2 highlights for the item, as we can only add 8 at a time.
    AssertEqual
    \ [
    \   {
    \     'group': 'ALEError', 'priority': 10, 'pos1': [1, 1, 1073741824],
    \     'pos2': [2], 'pos3': [3], 'pos4': [4], 'pos5': [5], 'pos6': [6],
    \     'pos7': [7], 'pos8': [8],
    \   },
    \   {
    \     'group': 'ALEError', 'priority': 10,
    \     'pos1': [9], 'pos2': [10, 1, 3]
    \   },
    \ ],
    \ GetMatchesWithoutIDs()
  endif

Execute(Highlights should always be cleared when the buffer highlight list is empty):
  if g:has_nvim_highlight
    " The newer API uses namespacing. We'll emulate it here.
    call ale#highlight#nvim_buf_add_highlight(
    \ bufnr(''),
    \ 1,
    \ 'ALEError',
    \ 0,
    \ 0,
    \ 1,
    \)

    AssertEqual
    \ [{'group': 'ALEError', 'priority': 10, 'pos1': [1, 1, 1]}],
    \ GetMatchesWithoutIDs()
  else
    " Add our highlights and something else.
    call matchaddpos('ALEError', [[1, 1, 1]])
    call matchaddpos('SomeOtherGroup', [[1, 1, 1]])

    AssertEqual
    \ [
    \   {'group': 'ALEError', 'priority': 10, 'pos1': [1, 1, 1]},
    \   {'group': 'SomeOtherGroup', 'priority': 10, 'pos1': [1, 1, 1]},
    \ ],
    \ GetMatchesWithoutIDs()
  endif


  " Set the List we use for holding highlights for buffers.
  let b:ale_highlight_items = []

  " Call the function for updating the highlights called when buffers
  " are entered, or when problems are presented.
  call ale#highlight#UpdateHighlights()

  " Check that we remove our highlights.
  if g:has_nvim_highlight
    AssertEqual [], GetMatchesWithoutIDs()
  else
    AssertEqual
    \ [{'group': 'SomeOtherGroup', 'priority': 10, 'pos1': [1, 1, 1]}],
    \ GetMatchesWithoutIDs()
  endif

Execute(Highlights should be hidden when excluded):
  let b:ale_exclude_highlights = ['ig.*ore', 'nope']

  call ale#highlight#SetHighlights(bufnr('%'), [
  \ {'bufnr': bufnr('%'), 'type': 'E', 'lnum': 1, 'col': 1, 'text': 'hello'},
  \ {'bufnr': bufnr('%'), 'type': 'E', 'lnum': 2, 'col': 1, 'text': 'ignore'},
  \ {'bufnr': bufnr('%'), 'type': 'E', 'lnum': 3, 'col': 1, 'text': 'nope'},
  \ {'bufnr': bufnr('%'), 'type': 'E', 'lnum': 4, 'col': 1, 'text': 'world'},
  \])

  AssertEqual
  \ [
  \   {'group': 'ALEError', 'priority': 10, 'pos1': [1, 1, 1]},
  \   {'group': 'ALEError', 'priority': 10, 'pos1': [4, 1, 1]},
  \ ],
  \ GetMatchesWithoutIDs()

Execute(Highlights should be cleared when ALE is disabled):
  let g:ale_enabled = 1
  call ale#highlight#SetHighlights(bufnr(''), [
  \ {'bufnr': bufnr(''), 'type': 'E', 'lnum': 1, 'col': 1, 'end_lnum': 10, 'end_col': 3},
  \])

  let g:ale_enabled = 0
  call ale#highlight#UpdateHighlights()

  AssertEqual [], GetMatchesWithoutIDs()

  let g:ale_enabled = 1
  call ale#highlight#SetHighlights(bufnr(''), [
  \ {'bufnr': bufnr(''), 'type': 'E', 'lnum': 1, 'col': 1, 'end_lnum': 10, 'end_col': 3},
  \])

  let b:ale_enabled = 0
  call ale#highlight#UpdateHighlights()

  AssertEqual [], GetMatchesWithoutIDs()

Execute(Line highlights should be set when signs are disabled):
  " This will mess with your settings, but it needs to be tested.
  " We need to match highlights case-insenstive when removing them.
  hi link aleerrorline spellbad

  let g:ale_set_signs = 0

  call ale#highlight#SetHighlights(bufnr(''), [
  \ {'bufnr': bufnr(''), 'type': 'E', 'lnum': 1, 'col': 1},
  \ {'bufnr': bufnr(''), 'type': 'W', 'lnum': 2, 'col': 1},
  \ {'bufnr': bufnr(''), 'type': 'I', 'lnum': 3, 'col': 1},
  \])

  if g:has_nvim_highlight
    " The output is different with the newer NeoVIM highlight API.
    AssertEqual
    \ [
    \   {'group': 'ALEError', 'priority': 10, 'pos1': [1, 1, 1]},
    \   {'group': 'ALEErrorLine', 'priority': 10, 'pos1': [1, 1, 1073741824]},
    \   {'group': 'ALEWarning', 'priority': 10, 'pos1': [2, 1, 1]},
    \   {'group': 'ALEWarningLine', 'priority': 10, 'pos1': [2, 1, 1073741824]},
    \   {'group': 'ALEInfo', 'priority': 10, 'pos1': [3, 1, 1]},
    \   {'group': 'ALEInfoLine', 'priority': 10, 'pos1': [3, 1, 1073741824]}
    \ ],
    \ GetMatchesWithoutIDs()
  else
    AssertEqual
    \ [
    \   {'group': 'ALEError', 'priority': 10, 'pos1': [1, 1, 1]},
    \   {'group': 'ALEWarning', 'priority': 10, 'pos1': [2, 1, 1]},
    \   {'group': 'ALEInfo', 'priority': 10, 'pos1': [3, 1, 1]},
    \   {'group': 'aleerrorline', 'priority': 10, 'pos1': [1]},
    \   {'group': 'ALEWarningLine', 'priority': 10, 'pos1': [2]},
    \   {'group': 'ALEInfoLine', 'priority': 10, 'pos1': [3]},
    \ ],
    \ GetMatchesWithoutIDs()
  endif

  " All of the highlights should be removed.
  call ale#highlight#RemoveHighlights()
  AssertEqual [], GetMatchesWithoutIDs()