Before:
  let g:ale_buffer_info = {
  \ bufnr('%'): {
  \   'loclist': [
  \     {
  \       'lnum': 1,
  \       'bufnr': bufnr('%'),
  \       'vcol': 0,
  \       'linter_name': 'eslint',
  \       'nr': -1,
  \       'type': 'E',
  \       'col': 10,
  \       'text': 'Missing semicolon. (semi)'
  \     },
  \     {
  \       'lnum': 2,
  \       'bufnr': bufnr('%'),
  \       'vcol': 0,
  \       'linter_name': 'eslint',
  \       'nr': -1,
  \       'type': 'W',
  \       'col': 10,
  \       'text': 'Infix operators must be spaced. (space-infix-ops)'
  \     },
  \     {
  \       'lnum': 2,
  \       'bufnr': bufnr('%'),
  \       'vcol': 0,
  \       'linter_name': 'eslint',
  \       'nr': -1,
  \       'type': 'E',
  \       'col': 15,
  \       'text': 'Missing radix parameter (radix)'
  \     }
  \   ],
  \ },
  \}

  " Turn off other features, we only care about this one feature in this test.
  let g:ale_set_loclist = 0
  let g:ale_set_signs = 0
  let g:ale_set_highlights = 0

After:
  let g:ale_set_loclist = 1
  let g:ale_set_signs = 1
  let g:ale_set_highlights = 1

  unlet! g:output
  unlet! g:lines
  let g:ale_buffer_info = {}

Given javascript(A Javscript file with warnings/errors):
  var x = 3
  var x = 5*2 + parseInt("10");

Execute(Evaluate the cursor function at line 1):
  :1
  call ale#cursor#EchoCursorWarning()

Then(Check the cursor output):
  redir => g:output
    silent mess
  redir END

  let g:lines = split(g:output, "\n")

  AssertEqual 'Missing semicolon. (semi)', g:lines[-1]

Execute(Evaluate the cursor function at line 2):
  :2
  call ale#cursor#EchoCursorWarning()

Then(Check the cursor output):
  redir => g:output
    silent mess
  redir END

  let g:lines = split(g:output, "\n")

  AssertEqual 'Infix operators must be spaced. (space-infix-ops)', g:lines[-1]

Execute(Evaluate the cursor function later in line 2):
  :2
  normal 16l
  call ale#cursor#EchoCursorWarning()

Then(Check the cursor output):
  redir => g:output
    silent mess
  redir END

  let g:lines = split(g:output, "\n")

  AssertEqual 'Missing radix parameter (radix)', g:lines[-1]

Execute(Set results for a lint cycle, with the cursor on line 1):
  :1
  call ale#engine#SetResults(
  \ bufnr('%'),
  \ g:ale_buffer_info[bufnr('%')].loclist,
  \)

Then(Check the cursor output):
  redir => g:output
    silent mess
  redir END

  let g:lines = split(g:output, "\n")

  AssertEqual 'Missing semicolon. (semi)', g:lines[-1]

Execute(Simulate leaving insert mode on line 2):
  :2
  normal 16h
  doautocmd InsertLeave

Then(Check the cursor output):
  redir => g:output
    silent mess
  redir END

  let g:lines = split(g:output, "\n")

  AssertEqual 'Infix operators must be spaced. (space-infix-ops)', g:lines[-1]