Execute(GCC errors from included files should be parsed correctly):
  AssertEqual
  \ [
  \   {
  \     'lnum': 3,
  \     'type': 'E',
  \     'text': 'Problems were found in the header (See :ALEDetail)',
  \     'detail': join([
  \       'broken.h:1:1: error: expected identifier or ''('' before ''{'' token',
  \       ' {{{',
  \       ' ^',
  \     ], "\n"),
  \   },
  \ ],
  \ ale#handlers#gcc#HandleGCCFormat(347, [
  \   'In file included from <stdin>:3:0:',
  \   'broken.h:1:1: error: expected identifier or ''('' before ''{'' token',
  \   ' {{{',
  \   ' ^',
  \ ])

  AssertEqual
  \ [
  \   {
  \     'lnum': 3,
  \     'type': 'E',
  \     'text': 'Problems were found in the header (See :ALEDetail)',
  \     'detail': join([
  \       'b.h:1:1: error: expected identifier or ''('' before ''{'' token',
  \       ' {{{',
  \       ' ^',
  \     ], "\n"),
  \   },
  \ ],
  \ ale#handlers#gcc#HandleGCCFormat(347, [
  \   'In file included from a.h:1:0,',
  \   '                 from test.c:3:',
  \   'b.h:1:1: error: expected identifier or ''('' before ''{'' token',
  \   ' {{{',
  \   ' ^',
  \ ])

  AssertEqual
  \ [
  \   {
  \     'lnum': 3,
  \     'type': 'E',
  \     'text': 'Problems were found in the header (See :ALEDetail)',
  \     'detail': join([
  \       'b.h:1:1: error: unknown type name ‘bad_type’',
  \       ' bad_type x;',
  \       ' ^',
  \       'b.h:2:1: error: unknown type name ‘other_bad_type’',
  \       ' other_bad_type y;',
  \       ' ^',
  \     ], "\n"),
  \   },
  \ ],
  \ ale#handlers#gcc#HandleGCCFormat(347, [
  \   'In file included from a.h:1:0,',
  \   '                 from test.c:3:',
  \   'b.h:1:1: error: unknown type name ‘bad_type’',
  \   ' bad_type x;',
  \   ' ^',
  \   'b.h:2:1: error: unknown type name ‘other_bad_type’',
  \   ' other_bad_type y;',
  \   ' ^',
  \ ])