MediaFile: detect missing numbers (fix #901)

beets/mediafile.py

@@ -154,11 +154,12 @@ def _safe_cast(out_type, val):
         else:
             if not isinstance(val, basestring):
                 val = unicode(val)
-            val = re.match(r'[\+-]?[0-9\.]*', val.strip()).group(0)
-            if not val:
-                return 0.0
-            else:
-                return float(val)
+            match = re.match(r'[\+-]?[0-9\.]+', val.strip())
+            if match:
+                val = match.group(0)
+                if val:
+                    return float(val)
+            return 0.0
 
     else:
         return val

docs/changelog.rst

@@ -77,6 +77,8 @@ Little improvements and fixes:
 * :doc:`/plugins/convert`: A new ``--pretend`` option lets you preview the
   commands the plugin will execute without actually taking any action. Thanks
   to Dietrich Daroch.
+* Fix a crash when a float-valued tag field only contained a ``+`` or ``-``
+  character.
 
 
 

test/test_mediafile_edge.py

@@ -107,6 +107,10 @@ class InvalidValueToleranceTest(unittest.TestCase):
         self.assertTrue(isinstance(us, unicode))
         self.assertTrue(us.startswith(u'caf'))
 
+    def test_safe_cast_float_with_no_numbers(self):
+        v = _sc(float, '+')
+        self.assertEqual(v, 0.0)
+
 
 class SafetyTest(unittest.TestCase, TestHelper):
     def setUp(self):