Execute(clang errors from included files should be parsed correctly):
  AssertEqual
  \ [
  \   {
  \     'lnum': 1,
  \     'col': 1,
  \     'filename': './b.h',
  \     'type': 'E',
  \     'text': 'expected identifier or ''(''',
  \   },
  \   {
  \     'lnum': 3,
  \     'text': 'Error found in header. See :ALEDetail',
  \     'detail': join([
  \       'In file included from <stdin>:3:',
  \       'In file included from ./a.h:1:',
  \       './b.h:1:1: error: expected identifier or ''(''',
  \       '{{{',
  \       '^',
  \     ], "\n"),
  \   },
  \ ],
  \ ale#handlers#gcc#HandleGCCFormatWithIncludes(347, [
  \   'In file included from <stdin>:3:',
  \   'In file included from ./a.h:1:',
  \   './b.h:1:1: error: expected identifier or ''(''',
  \   '{{{',
  \   '^',
  \   '1 error generated.',
  \ ])