Before:
  call ale#test#SetDirectory('/testplugin/test/handler')
  call ale#test#SetFilename('testfile.less')

  runtime ale_linters/less/lessc.vim

After:
  call ale#test#RestoreDirectory()
  call ale#linter#Reset()

Execute(The lessc handler should handle errors for the current file correctly):
  AssertEqual
  \ [
  \   {
  \     'lnum': 2,
  \     'col': 1,
  \     'type': 'E',
  \     'text': 'Unrecognised input. Possibly missing something',
  \   },
  \ ],
  \ ale_linters#less#lessc#Handle(bufnr(''), [
  \   'ParseError: Unrecognised input. Possibly missing something in - on line 2, column 1:',
  \   '1 vwewww',
  \   '2    ',
  \])

Execute(The lessc handler should handle errors for other files in the same directory correctly):
  AssertEqual
  \ [
  \   {
  \     'lnum': 2,
  \     'col': 1,
  \     'type': 'E',
  \     'text': 'Unrecognised input. Possibly missing something',
  \     'filename': ale#path#Simplify(g:dir . '/imported.less')
  \   },
  \   {
  \     'lnum': 2,
  \     'col': 1,
  \     'type': 'E',
  \     'text': 'Unrecognised input. Possibly missing something',
  \     'filename': ale#path#Simplify(g:dir . '/imported.less')
  \   },
  \ ],
  \ ale_linters#less#lessc#Handle(bufnr(''), [
  \   'ParseError: Unrecognised input. Possibly missing something in imported.less on line 2, column 1:',
  \   '1 vwewww',
  \   '2    ',
  \   'ParseError: Unrecognised input. Possibly missing something in ./imported.less on line 2, column 1:',
  \   '1 vwewww',
  \   '2    ',
  \])

Execute(The lessc handler should handle errors for files in directories above correctly):
  AssertEqual
  \ [
  \   {
  \     'lnum': 2,
  \     'col': 1,
  \     'type': 'E',
  \     'text': 'Unrecognised input. Possibly missing something',
  \     'filename': ale#path#Simplify(g:dir . '/../imported2.less')
  \   },
  \ ],
  \ ale_linters#less#lessc#Handle(bufnr(''), [
  \   'ParseError: Unrecognised input. Possibly missing something in ../imported2.less on line 2, column 1:',
  \   '1 vwewww',
  \   '2    ',
  \])