Rewrite syntax errors handling and test them

If a syntax errors occurs at the same place than a regular yamllint rule
error, only the yamllint one is issued.

tests/rules/test_document_end.py

@@ -64,12 +64,6 @@ class DocumentEndTestCase(RuleTestCase):
                    '---\n'
                    'third: document\n'
                    '...\n', conf)
-        self.check('first: document\n'
-                   '...\n'
-                   'second: document\n'
-                   '...\n'
-                   'third: document\n'
-                   '...\n', conf)
         self.check('---\n'
                    'first: document\n'
                    '...\n'

tests/rules/test_syntax_error.py

@@ -0,0 +1,31 @@
+# -*- coding: utf-8 -*-
+# Copyright (C) 2016 Adrien Vergé
+#
+# This program is free software: you can redistribute it and/or modify
+# it under the terms of the GNU General Public License as published by
+# the Free Software Foundation, either version 3 of the License, or
+# (at your option) any later version.
+#
+# This program is distributed in the hope that it will be useful,
+# but WITHOUT ANY WARRANTY; without even the implied warranty of
+# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+# GNU General Public License for more details.
+#
+# You should have received a copy of the GNU General Public License
+# along with this program.  If not, see <http://www.gnu.org/licenses/>.
+
+from tests.rules.common import RuleTestCase
+
+
+class YamlLintTestCase(RuleTestCase):
+    rule_id = None  # syntax error
+
+    def test_lint(self):
+        self.check('---\n'
+                   'this is not: valid: YAML\n', None, problem=(2, 19))
+        self.check('---\n'
+                   'this is: valid YAML\n'
+                   '\n'
+                   'this is an error: [\n'
+                   '\n'
+                   '...\n', None, problem=(6, 1))