Enforcing lowercase currency for CourseMode

- CourseMode.save() always lowercases the currency value
- CourseMode currency comparisons have been updated to be case-insensitive

common/djangoapps/course_modes/models.py

@@ -86,6 +86,11 @@ class CourseMode(models.Model):
         """ meta attributes of this model """
         unique_together = ('course_id', 'mode_slug', 'currency')
 
+    def save(self, force_insert=False, force_update=False, using=None):
+        # Ensure currency is always lowercase.
+        self.currency = self.currency.lower()
+        super(CourseMode, self).save(force_insert, force_update, using)
+
     @classmethod
     def all_modes_for_courses(cls, course_id_list):
         """Find all modes for a list of course IDs, including expired modes.
@@ -308,7 +313,7 @@ class CourseMode(models.Model):
         """
         modes = cls.modes_for_course(course_id)
         for mode in modes:
-            if (mode.currency == currency) and (mode.slug == 'verified'):
+            if (mode.currency.lower() == currency.lower()) and (mode.slug == 'verified'):
                 return mode.min_price
         return 0
 
@@ -490,7 +495,7 @@ class CourseMode(models.Model):
         If there is no mode found, will return the price of DEFAULT_MODE, which is 0
         """
         modes = cls.modes_for_course(course_id)
-        return min(mode.min_price for mode in modes if mode.currency == currency)
+        return min(mode.min_price for mode in modes if mode.currency.lower() == currency.lower())
 
     @classmethod
     def enrollment_mode_display(cls, mode, verification_status):

common/djangoapps/course_modes/tests/test_models.py

@@ -39,6 +39,15 @@ class CourseModeModelTest(TestCase):
             currency=currency,
         )
 
+    def test_save(self):
+        """ Verify currency is always lowercase. """
+        cm, __ = self.create_mode('honor', 'honor', 0, '', 'USD')
+        self.assertEqual(cm.currency, 'usd')
+
+        cm.currency = 'GHS'
+        cm.save()
+        self.assertEqual(cm.currency, 'ghs')
+
     def test_modes_for_course_empty(self):
         """
         If we can't find any modes, we should get back the default mode

lms/djangoapps/commerce/api/v1/tests/test_views.py

@@ -33,7 +33,7 @@ class CourseApiViewTestMixin(object):
         """ Serialize a CourseMode to a dict. """
         return {
             u'name': course_mode.mode_slug,
-            u'currency': course_mode.currency,
+            u'currency': course_mode.currency.lower(),
             u'price': course_mode.min_price,
             u'sku': course_mode.sku
         }

lms/djangoapps/shoppingcart/processors/CyberSource2.py

@@ -357,7 +357,7 @@ def _payment_accepted(order_id, auth_amount, currency, decision):
         raise CCProcessorDataException(_("The payment processor accepted an order whose number is not in our system."))
 
     if decision == 'ACCEPT':
-        if auth_amount == order.total_cost and currency == order.currency:
+        if auth_amount == order.total_cost and currency.lower() == order.currency.lower():
             return {
                 'accepted': True,
                 'amt_charged': auth_amount,