slight code reduction

django_auth_lti/tests/test_verification.py

@@ -2,12 +2,11 @@ from unittest import TestCase
 from mock import MagicMock
 from django_auth_lti.verification import is_allowed
 from django.core.exceptions import ImproperlyConfigured, PermissionDenied
-from django.http import HttpRequest
 
 class TestVerification(TestCase):
     
     def test_is_allowed_config_failure(self):
-        request = MagicMock(session={"LTI_LAUNCH": None})
+        request = MagicMock(session={})
         allowed_roles = ["admin", "student"]
         self.assertRaises(ImproperlyConfigured, is_allowed,
                           request, allowed_roles, False)

django_auth_lti/verification.py

@@ -8,12 +8,12 @@ def is_allowed(request, allowed_roles, raise_exception):
     else:
         allowed = allowed_roles
     
-    lti_params = request.session.get('LTI_LAUNCH', None)
-    if lti_params is None:
+    if ("LTI_LAUNCH" not in request.session
+        or request.session["LTI_LAUNCH"] is None):
         # If this is raised, then likely the project doesn't have
         # the correct settings or is being run outside of an lti context
         raise ImproperlyConfigured("No LTI_LAUNCH vale found in session")
-    user_roles = lti_params.get('roles', [])
+    user_roles = request.session['LTI_LAUNCH'].get('roles', [])
     is_user_allowed =  set(allowed) & set(user_roles)
     
     if not is_user_allowed and raise_exception: