Execute(The golang handler should return the correct filenames):
  AssertEqual
  \ [
  \   {
  \     'lnum': 27,
  \     'col': 0,
  \     'text': 'some error',
  \     'type': 'E',
  \     'filename': ale#path#Simplify(expand('%:p:h') . '/test.go'),
  \   },
  \   {
  \     'lnum': 27,
  \     'col': 5,
  \     'text': 'some error with a column',
  \     'type': 'E',
  \     'filename': ale#path#Simplify(expand('%:p:h') . '/other.go'),
  \   },
  \ ],
  \ ale#handlers#go#Handler(bufnr(''), [
  \   'test.go:27: some error',
  \   'other.go:27:5: some error with a column',
  \ ])