Rules: document-start: Allow directives

tests/rules/test_document_start.py

@@ -85,6 +85,20 @@ class DocumentStartTestCase(RuleTestCase):
                    'third: document\n', conf, problem=(4, 1))
 
     def test_directives(self):
-        # TODO
-        # %YAML 1.2
-        pass
+        conf = 'document-start: {present: yes}'
+        self.check('%YAML 1.2\n'
+                   '---\n'
+                   'doc: ument\n'
+                   '...\n', conf)
+        self.check('%YAML 1.2\n'
+                   '%TAG ! tag:clarkevans.com,2002:\n'
+                   '---\n'
+                   'doc: ument\n'
+                   '...\n', conf)
+        self.check('---\n'
+                   'doc: 1\n'
+                   '...\n'
+                   '%YAML 1.2\n'
+                   '---\n'
+                   'doc: 2\n'
+                   '...\n', conf)

tests/rules/test_syntax_error.py

@@ -29,3 +29,9 @@ class YamlLintTestCase(RuleTestCase):
                    'this is an error: [\n'
                    '\n'
                    '...\n', None, problem=(6, 1))
+
+    def test_directives(self):
+        self.check('%YAML 1.2\n'
+                   '%TAG ! tag:clarkevans.com,2002:\n'
+                   'doc: ument\n'
+                   '...\n', None, problem=(3, 1))

yamllint/rules/document_start.py

@@ -24,15 +24,14 @@ TYPE = 'token'
 CONF = {'present': bool}
 
 
-# TODO: Don't fail if document contains directives such as
-# %YAML 1.2
-
 def check(conf, token, prev, next):
     if conf['present']:
-        if ((isinstance(prev, yaml.StreamStartToken) or
-             isinstance(prev, yaml.DocumentEndToken)) and
-            not (isinstance(token, yaml.DocumentStartToken) or
-                 isinstance(token, yaml.StreamEndToken))):
+        if (isinstance(prev, (yaml.StreamStartToken,
+                              yaml.DocumentEndToken,
+                              yaml.DirectiveToken)) and
+            not isinstance(token, (yaml.DocumentStartToken,
+                                   yaml.DirectiveToken,
+                                   yaml.StreamEndToken))):
             yield LintProblem(token.start_mark.line + 1, 1,
                               'missing document start "---"')