AbbrExtension now handles abbreviations nested in other markup.

Just set each abreviation as an AtomicString. Given the nature of
abbreviations, they are not likely to ever contain any other markup
anyway. Also added a test.

Fixes #224. Thanks for the report @JakeChampion.

2 files changed, 11 insertions, 2 deletions

diff --git a/markdown/extensions/abbr.py b/markdown/extensions/abbr.py
index 5e46f1d..3f8a443 100644
--- a/markdown/extensions/abbr.py
+++ b/markdown/extensions/abbr.py
@@ -28,7 +28,7 @@ from __future__ import unicode_literals
 from . import Extension
 from ..preprocessors import Preprocessor
 from ..inlinepatterns import Pattern
-from ..util import etree
+from ..util import etree, AtomicString
 import re
 
 # Global Vars
@@ -88,7 +88,7 @@ class AbbrPattern(Pattern):
 
     def handleMatch(self, m):
         abbr = etree.Element('abbr')
-        abbr.text = m.group('abbr')
+        abbr.text = AtomicString(m.group('abbr'))
         abbr.set('title', self.title)
         return abbr
 
diff --git a/tests/test_extensions.py b/tests/test_extensions.py
index cb27a30..cce2adf 100644
--- a/tests/test_extensions.py
+++ b/tests/test_extensions.py
@@ -27,6 +27,15 @@ class TestAbbr(unittest.TestCase):
             'and a <abbr title="Abbreviation Reference">REF</abbr>. Ignore '
             'REFERENCE and ref.</p>')
 
+    def testNestedAbbr(self):
+        """ Test Nested Abbreviations. """
+        text = '[ABBR](/foo) and _ABBR_\n\n' + \
+               '*[ABBR]: Abreviation'
+        self.assertEqual(self.md.convert(text),
+            '<p><a href="/foo"><abbr title="Abreviation">ABBR</abbr></a> '
+            'and <em><abbr title="Abreviation">ABBR</abbr></em></p>')
+
+
 class TestCodeHilite(unittest.TestCase):
     """ Test codehilite extension. """