Merge pull request #4051 from edx/anton/i18n-choicetextgroup

ChoiceTextGroup i18n.

common/lib/capa/capa/inputtypes.py

@@ -1661,23 +1661,28 @@ class ChoiceTextGroup(InputTypeBase):
         elif self.tag == 'checkboxtextgroup':
             self.html_input_type = "checkbox"
         else:
-            raise Exception("ChoiceGroup: unexpected tag {0}".format(self.tag))
+            _ = self.capa_system.i18n.ugettext
+            msg = _("{input_type}: unexpected tag {tag_name}").format(
+                input_type="ChoiceTextGroup", tag_name=self.tag
+            )
+            raise Exception(msg)
 
         if self.value == '':
             # Make `value` an empty dictionary, if it currently has an empty
             # value. This is necessary because the template expects a
             # dictionary.
             self.value = {}
-        self.choices = self.extract_choices(self.xml)
+        self.choices = self.extract_choices(self.xml, self.capa_system.i18n)
 
     @classmethod
     def get_attributes(cls):
         """
         Returns a list of `Attribute` for this problem type
         """
+        _ = lambda text: text
         return [
             Attribute("show_correctness", "always"),
-            Attribute("submitted_message", "Answer received."),
+            Attribute("submitted_message", _("Answer received.")),
             Attribute("label", ""),
         ]
 
@@ -1694,7 +1699,7 @@ class ChoiceTextGroup(InputTypeBase):
         }
 
     @staticmethod
-    def extract_choices(element):
+    def extract_choices(element, i18n):
         """
         Extracts choices from the xml for this problem type.
         If we have xml that is as follows(choice names will have been assigned
@@ -1734,14 +1739,19 @@ class ChoiceTextGroup(InputTypeBase):
         ]
         """
 
+        _ = i18n.ugettext
         choices = []
 
         for choice in element:
             if choice.tag != 'choice':
-                raise Exception(
-                    "[capa.inputtypes.extract_choices] Expected a <choice>" +
-                    "tag; got {0} instead".format(choice.tag)
+                msg = "[capa.inputtypes.extract_choices] {0}".format(
+                    # Translators: a "tag" is an XML element, such as "<b>" in HTML
+                    _("Expected a {expected_tag} tag; got {given_tag} instead").format(
+                        expected_tag=u"<choice>",
+                        given_tag=choice.tag,
+                    )
                 )
+                raise Exception(msg)
 
             components = []
             choice_text = ''