Improve bbcode highlighter and add testcase for it

Signed-off-by: Michal Čihař <michal@cihar.com>

weblate/trans/checks/markup.py

@@ -26,7 +26,7 @@ from django.utils.translation import ugettext_lazy as _
 from weblate.trans.checks.base import TargetCheck
 
 BBCODE_MATCH = re.compile(
-    r'\[(?P<tag>[^]]*)(?=(@[^]]*)?\](.*?)\[\/(?P=tag)\])',
+    r'(?P<start>\[(?P<tag>[^]]+)(@[^]]*)?\])(.*?)(?P<end>\[\/(?P=tag)\])',
     re.MULTILINE
 )
 
@@ -61,8 +61,8 @@ class BBCodeCheck(TargetCheck):
         if len(src_match) != len(tgt_match):
             return True
 
-        src_tags = set([x[0] for x in src_match])
-        tgt_tags = set([x[0] for x in tgt_match])
+        src_tags = set([x[1] for x in src_match])
+        tgt_tags = set([x[1] for x in tgt_match])
 
         return src_tags != tgt_tags
 
@@ -70,13 +70,12 @@ class BBCodeCheck(TargetCheck):
         if self.should_skip(unit):
             return []
         ret = []
-        match_objects = BBCODE_MATCH.finditer(source)
-        for match in match_objects:
-            if match.start() == match.end():
-                continue
-            ret.append((match.start(), match.group()))
+        for match in BBCODE_MATCH.finditer(source):
+            ret.append((match.start('start'), match.group('start')))
+            ret.append((match.start('end'), match.group('end')))
         return ret
 
+
 class XMLTagsCheck(TargetCheck):
     '''
     Check whether XML in target matches source.

weblate/trans/tests/test_markup_checks.py

@@ -37,6 +37,10 @@ class BBCodeCheckTest(CheckTestCase):
         self.test_good_matching = ('[a]string[/a]', '[a]string[/a]', '')
         self.test_failure_1 = ('[a]string[/a]', '[b]string[/b]', '')
         self.test_failure_2 = ('[a]string[/a]', 'string', '')
+        self.test_highlight = (
+            '[a]string[/a]',
+            [(0, '[a]'), (9, '[/a]')]
+        )
 
 
 class XMLTagsCheckTest(CheckTestCase):