Accept an alternate username generation algo in settings for user cre…

…ation

django_browserid/auth.py

@@ -21,6 +21,15 @@
 OKAY_RESPONSE = 'okay'
 
 
+def default_username_algo(email):
+    # store the username as a base64 encoded sha1 of the email address
+    # this protects against data leakage because usernames are often
+    # treated as public identifiers (so we can't use the email address).
+    username = base64.urlsafe_b64encode(
+        hashlib.sha1(email).digest()).rstrip('=')
+    return username
+
+
 class BrowserIDBackend(object):
     supports_anonymous_user = False
     supports_object_permissions = False
@@ -66,12 +75,9 @@ def authenticate(self, assertion=None, host=None, port=None):
         create_user = getattr(settings, 'BROWSERID_CREATE_USER', False)
         if not create_user:
             return None
-        # store the username as a base64 encoded sha1 of the email address
-        # this protects against data leakage because usernames are often
-        # treated as public identifiers (so we can't use the email address).
-        username = base64.urlsafe_b64encode(
-            hashlib.sha1(email).digest()).rstrip('=')
-        user = User.objects.create_user(username, email)
+        username_algo = getattr(settings, 'BROWSERID_USERNAME_ALGO',
+                                default_username_algo)
+        user = User.objects.create_user(username_algo(email), email)
         user.is_active = True
         user.save()
         return user

django_browserid/tests/test_verification.py

@@ -85,6 +85,7 @@ def test_authenticate_create_user(fake):
     """Test that automatic user creation works when enabled."""
     with positive_assertion(fake):
         setattr(settings, 'BROWSERID_CREATE_USER', True)
+        delattr(settings, 'BROWSERID_USERNAME_ALGO')
         user = auth.authenticate(**authenticate_kwargs)
         # user should have been created
         assert user
@@ -93,6 +94,23 @@ def test_authenticate_create_user(fake):
             hashlib.sha1(user.email).digest()).rstrip('=')
 
 
+@fudge.patch('django_browserid.auth.BrowserIDBackend._verify_http_request')
+def test_authenticate_create_user_with_alternate_username_algo(fake):
+    """Test that automatic user creation with an alternate username algo
+    works."""
+
+    def username_algo(email):
+        return email.split('@')[0]
+
+    with positive_assertion(fake, email=u'myemail@example.org'):
+        setattr(settings, 'BROWSERID_CREATE_USER', True)
+        setattr(settings, 'BROWSERID_USERNAME_ALGO', username_algo)
+        user = auth.authenticate(**authenticate_kwargs)
+        assert user
+        assert user.email == 'myemail@example.org'
+        assert user.username == 'myemail'
+
+
 @fudge.patch('django_browserid.auth.BrowserIDBackend._verify_http_request')
 def test_authenticate_missing_user(fake):
     """Test that authenticate() returns None when user creation disabled."""