Add a test to cover invalid link case for email update

tests/functional/accounts/test_update_email.py

@@ -86,13 +86,16 @@ class TestUpdateEmail(TransactionTestController):
         return token
 
     def _submit_token(self, token, email, invalid=False, error=None,
-                      redirect=None):
+                      redirect=None, submit_data=None):
+
+        if not submit_data:
             user = User.objects.get(email=self._AUTHDATA['username'])
             submit_data = {
                 'uidb64': urlsafe_base64_encode(force_bytes(user.pk)),
                 'token': token,
                 'email': email,
             }
+
         submit_url = reverse('email_change_confirm', kwargs=submit_data)
         response = self.client.get(submit_url)
 
@@ -173,6 +176,16 @@ class TestUpdateEmail(TransactionTestController):
         self._submit_token(token, 'new@example.org',
                            error='address already exists')
 
+    def test_update_email_invalid_taken(self):
+        invalid_data = {
+            'uidb64': 'a',
+            'token': 'x-x',
+            'email': 'a',
+        }
+
+        self._submit_token(None, 'new@example.org',
+                           invalid=True, submit_data=invalid_data)
+
     def test_update_email_mismatch_email(self):
         token = self._get_update_token('new@example.org')