linter: Fix UnicodeError when parsing comments

And add tests when reading non-ASCII strings and comments (both from
Python strings and from files).

Fixes: #10

yamllint/linter.py

@@ -71,7 +71,10 @@ def get_costemic_problems(buffer, conf):
             self.all_rules = set([r.ID for r in rules])
 
         def process_comment(self, comment):
-            comment = repr(comment)
+            try:
+                comment = str(comment)
+            except UnicodeError:
+                return  # this certainly wasn't a yamllint directive comment
 
             if re.match(r'^# yamllint disable( rule:\S+)*\s*$', comment):
                 rules = [item[5:] for item in comment[18:].split(' ')][1:]
@@ -95,7 +98,10 @@ def get_costemic_problems(buffer, conf):
 
     class DisableLineDirective(DisableDirective):
         def process_comment(self, comment):
-            comment = repr(comment)
+            try:
+                comment = str(comment)
+            except UnicodeError:
+                return  # this certainly wasn't a yamllint directive comment
 
             if re.match(r'^# yamllint disable-line( rule:\S+)*\s*$', comment):
                 rules = [item[5:] for item in comment[23:].split(' ')][1:]

yamllint/parser.py

@@ -49,7 +49,7 @@ class Comment(object):
         self.token_after = token_after
         self.comment_before = comment_before
 
-    def __repr__(self):
+    def __str__(self):
         end = self.buffer.find('\n', self.pointer)
         if end == -1:
             end = self.buffer.find('\0', self.pointer)