diff --git a/passbook/policies/expression/evaluator.py b/passbook/policies/expression/evaluator.py
index 39943202d..2a0e0193a 100644
--- a/passbook/policies/expression/evaluator.py
+++ b/passbook/policies/expression/evaluator.py
@@ -19,7 +19,7 @@ LOGGER = get_logger()
 
 
 class Evaluator:
-    """Validate and evaulate jinja2-based expressions"""
+    """Validate and evaluate jinja2-based expressions"""
 
     _env: NativeEnvironment
 
@@ -51,14 +51,15 @@ class Evaluator:
         """Return dictionary with additional global variables passed to expression"""
         # update passbook/policies/expression/templates/policy/expression/form.html
         # update docs/policies/expression/index.md
-        kwargs["pb_is_sso_flow"] = request.http_request.session.get(
-            AuthenticationView.SESSION_IS_SSO_LOGIN, False
-        )
         kwargs["pb_is_group_member"] = Evaluator.jinja2_func_is_group_member
         kwargs["pb_logger"] = get_logger()
-        kwargs["pb_client_ip"] = (
-            get_client_ip(request.http_request) or "255.255.255.255"
-        )
+        if request.http_request:
+            kwargs["pb_is_sso_flow"] = request.http_request.session.get(
+                AuthenticationView.SESSION_IS_SSO_LOGIN, False
+            )
+            kwargs["pb_client_ip"] = (
+                get_client_ip(request.http_request) or "255.255.255.255"
+            )
         return kwargs
 
     def evaluate(self, expression_source: str, request: PolicyRequest) -> PolicyResult:
@@ -81,7 +82,7 @@ class Evaluator:
                     req=request,
                 )
                 return PolicyResult(False)
-            if isinstance(result, list) and len(result) == 2:
+            if isinstance(result, (list, tuple)) and len(result) == 2:
                 return PolicyResult(*result)
             if result:
                 return PolicyResult(result)
diff --git a/passbook/policies/expression/tests/__init__.py b/passbook/policies/expression/tests/__init__.py
new file mode 100644
index 000000000..e69de29bb
diff --git a/passbook/policies/expression/tests/test_evaluator.py b/passbook/policies/expression/tests/test_evaluator.py
new file mode 100644
index 000000000..ca22e86ec
--- /dev/null
+++ b/passbook/policies/expression/tests/test_evaluator.py
@@ -0,0 +1,58 @@
+"""evaluator tests"""
+from django.core.exceptions import ValidationError
+from django.test import TestCase
+from guardian.shortcuts import get_anonymous_user
+
+from passbook.policies.expression.evaluator import Evaluator
+from passbook.policies.types import PolicyRequest
+
+
+class TestEvaluator(TestCase):
+    """Evaluator tests"""
+
+    def setUp(self):
+        self.request = PolicyRequest(user=get_anonymous_user())
+
+    def test_valid(self):
+        """test simple value expression"""
+        template = "True"
+        evaluator = Evaluator()
+        self.assertEqual(evaluator.evaluate(template, self.request).passing, True)
+
+    def test_messages(self):
+        """test expression with message return"""
+        template = "False, 'some message'"
+        evaluator = Evaluator()
+        result = evaluator.evaluate(template, self.request)
+        self.assertEqual(result.passing, False)
+        self.assertEqual(result.messages, ("some message",))
+
+    def test_invalid_syntax(self):
+        """test invalid syntax"""
+        template = "{%"
+        evaluator = Evaluator()
+        result = evaluator.evaluate(template, self.request)
+        self.assertEqual(result.passing, False)
+        self.assertEqual(result.messages, ("tag name expected",))
+
+    def test_undefined(self):
+        """test undefined result"""
+        template = "{{ foo.bar }}"
+        evaluator = Evaluator()
+        result = evaluator.evaluate(template, self.request)
+        self.assertEqual(result.passing, False)
+        self.assertEqual(result.messages, ("'foo' is undefined",))
+
+    def test_validate(self):
+        """test validate"""
+        template = "True"
+        evaluator = Evaluator()
+        result = evaluator.validate(template)
+        self.assertEqual(result, True)
+
+    def test_validate_invalid(self):
+        """test validate"""
+        template = "{%"
+        evaluator = Evaluator()
+        with self.assertRaises(ValidationError):
+            evaluator.validate(template)
diff --git a/passbook/policies/types.py b/passbook/policies/types.py
index 99bb890cc..fd549589a 100644
--- a/passbook/policies/types.py
+++ b/passbook/policies/types.py
@@ -1,7 +1,7 @@
 """policy structures"""
 from __future__ import annotations
 
-from typing import TYPE_CHECKING, Tuple
+from typing import TYPE_CHECKING, Optional, Tuple
 
 from django.db.models import Model
 from django.http import HttpRequest
@@ -14,11 +14,13 @@ class PolicyRequest:
     """Data-class to hold policy request data"""
 
     user: User
-    http_request: HttpRequest
-    obj: Model
+    http_request: Optional[HttpRequest]
+    obj: Optional[Model]
 
     def __init__(self, user: User):
         self.user = user
+        self.http_request = None
+        self.obj = None
 
     def __str__(self):
         return f"<PolicyRequest user={self.user}>"