policies/expression: use pb_message() for messages instead of returning a tuple
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@ -13,7 +13,6 @@ from django.utils.translation import gettext_lazy as _
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from guardian.mixins import GuardianUserMixin
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from jinja2 import Undefined
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from jinja2.exceptions import TemplateSyntaxError, UndefinedError
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from jinja2.nativetypes import NativeEnvironment
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from model_utils.managers import InheritanceManager
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from structlog import get_logger
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@ -24,7 +23,6 @@ from passbook.lib.models import CreatedUpdatedModel
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from passbook.policies.models import PolicyBindingModel
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LOGGER = get_logger()
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NATIVE_ENVIRONMENT = NativeEnvironment()
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def default_token_duration():
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@ -208,8 +206,11 @@ class PropertyMapping(models.Model):
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self, user: Optional[User], request: Optional[HttpRequest], **kwargs
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) -> Any:
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"""Evaluate `self.expression` using `**kwargs` as Context."""
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from passbook.policies.expression.evaluator import Evaluator
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evaluator = Evaluator()
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try:
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expression = NATIVE_ENVIRONMENT.from_string(self.expression)
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expression = evaluator.env.from_string(self.expression)
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except TemplateSyntaxError as exc:
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raise PropertyMappingExpressionException from exc
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try:
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@ -221,8 +222,11 @@ class PropertyMapping(models.Model):
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raise PropertyMappingExpressionException from exc
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def save(self, *args, **kwargs):
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from passbook.policies.expression.evaluator import Evaluator
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evaluator = Evaluator()
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try:
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NATIVE_ENVIRONMENT.from_string(self.expression)
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evaluator.env.from_string(self.expression)
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except TemplateSyntaxError as exc:
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raise ValidationError("Expression Syntax Error") from exc
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return super().save(*args, **kwargs)
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@ -1,8 +1,9 @@
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"""passbook expression policy evaluator"""
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import re
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from typing import TYPE_CHECKING, Any, Dict, Optional
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from typing import TYPE_CHECKING, Any, Dict, List, Optional
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from django.core.exceptions import ValidationError
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from django.http import HttpRequest
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from jinja2 import Undefined
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from jinja2.exceptions import TemplateSyntaxError
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from jinja2.nativetypes import NativeEnvironment
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@ -25,12 +26,32 @@ class Evaluator:
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_env: NativeEnvironment
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_context: Dict[str, Any]
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_messages: List[str]
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def __init__(self):
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self._env = NativeEnvironment()
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self._env = NativeEnvironment(
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extensions=["jinja2.ext.do",],
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trim_blocks=True,
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lstrip_blocks=True,
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line_statement_prefix=">",
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)
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# update passbook/policies/expression/templates/policy/expression/form.html
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# update docs/policies/expression/index.md
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self._env.filters["regex_match"] = Evaluator.jinja2_filter_regex_match
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self._env.filters["regex_replace"] = Evaluator.jinja2_filter_regex_replace
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self._env.globals["pb_message"] = self.jinja2_func_message
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self._context = {
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"pb_is_group_member": Evaluator.jinja2_func_is_group_member,
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"pb_logger": get_logger(),
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"requests": Session(),
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}
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self._messages = []
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@property
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def env(self) -> NativeEnvironment:
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"""Access to our custom NativeEnvironment"""
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return self._env
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@staticmethod
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def jinja2_filter_regex_match(value: Any, regex: str) -> bool:
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@ -47,52 +68,57 @@ class Evaluator:
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"""Check if `user` is member of group with name `group_name`"""
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return user.groups.filter(name=group_name).exists()
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def _get_expression_context(
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self, request: PolicyRequest, **kwargs
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) -> Dict[str, Any]:
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"""Return dictionary with additional global variables passed to expression"""
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def jinja2_func_message(self, message: str):
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"""Wrapper to append to messages list, which is returned with PolicyResult"""
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self._messages.append(message)
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def set_policy_request(self, request: PolicyRequest):
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"""Update context based on policy request (if http request is given, update that too)"""
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# update passbook/policies/expression/templates/policy/expression/form.html
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# update docs/policies/expression/index.md
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kwargs["pb_is_group_member"] = Evaluator.jinja2_func_is_group_member
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kwargs["pb_logger"] = get_logger()
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kwargs["requests"] = Session()
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kwargs["pb_is_sso_flow"] = request.context.get(PLAN_CONTEXT_SSO, False)
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self._context["pb_is_sso_flow"] = request.context.get(PLAN_CONTEXT_SSO, False)
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self._context["request"] = request
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if request.http_request:
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kwargs["pb_client_ip"] = (
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get_client_ip(request.http_request) or "255.255.255.255"
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)
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if SESSION_KEY_PLAN in request.http_request.session:
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kwargs["pb_flow_plan"] = request.http_request.session[SESSION_KEY_PLAN]
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return kwargs
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self.set_http_request(request.http_request)
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def evaluate(self, expression_source: str, request: PolicyRequest) -> PolicyResult:
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"""Parse and evaluate expression.
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If the Expression evaluates to a list with 2 items, the first is used as passing bool and
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the second as messages.
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If the Expression evaluates to a truthy-object, it is used as passing bool."""
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def set_http_request(self, request: HttpRequest):
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"""Update context based on http request"""
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# update passbook/policies/expression/templates/policy/expression/form.html
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# update docs/policies/expression/index.md
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self._context["pb_client_ip"] = (
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get_client_ip(request.http_request) or "255.255.255.255"
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)
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self._context["request"] = request
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if SESSION_KEY_PLAN in request.http_request.session:
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self._context["pb_flow_plan"] = request.http_request.session[
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SESSION_KEY_PLAN
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]
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def evaluate(self, expression_source: str) -> PolicyResult:
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"""Parse and evaluate expression. Policy is expected to return a truthy object.
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Messages can be added using 'do pb_message()'."""
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try:
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expression = self._env.from_string(expression_source)
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expression = self._env.from_string(expression_source.lstrip().rstrip())
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except TemplateSyntaxError as exc:
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return PolicyResult(False, str(exc))
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try:
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result: Optional[Any] = expression.render(
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request=request, **self._get_expression_context(request)
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)
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result: Optional[Any] = expression.render(self._context)
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except Exception as exc: # pylint: disable=broad-except
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LOGGER.warning("Expression error", exc=exc)
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return PolicyResult(False, str(exc))
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else:
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policy_result = PolicyResult(False)
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policy_result.messages = tuple(self._messages)
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if isinstance(result, Undefined):
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LOGGER.warning(
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"Expression policy returned undefined",
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src=expression_source,
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req=request,
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req=self._context,
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)
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return PolicyResult(False)
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if isinstance(result, (list, tuple)) and len(result) == 2:
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return PolicyResult(*result)
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policy_result.passing = False
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if result:
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return PolicyResult(bool(result))
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return PolicyResult(False)
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except Exception as exc: # pylint: disable=broad-except
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LOGGER.warning("Expression error", exc=exc)
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return PolicyResult(False, str(exc))
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policy_result.passing = bool(result)
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return policy_result
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def validate(self, expression: str):
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"""Validate expression's syntax, raise ValidationError if Syntax is invalid"""
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@ -16,7 +16,9 @@ class ExpressionPolicy(Policy):
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def passes(self, request: PolicyRequest) -> PolicyResult:
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"""Evaluate and render expression. Returns PolicyResult(false) on error."""
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return Evaluator().evaluate(self.expression, request)
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evaluator = Evaluator()
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evaluator.set_policy_request(request)
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return evaluator.evaluate(self.expression)
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def save(self, *args, **kwargs):
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Evaluator().validate(self.expression)
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@ -17,13 +17,15 @@ class TestEvaluator(TestCase):
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"""test simple value expression"""
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template = "True"
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evaluator = Evaluator()
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self.assertEqual(evaluator.evaluate(template, self.request).passing, True)
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evaluator.set_policy_request(self.request)
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self.assertEqual(evaluator.evaluate(template).passing, True)
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def test_messages(self):
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"""test expression with message return"""
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template = "False, 'some message'"
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template = '{% do pb_message("some message") %}False'
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evaluator = Evaluator()
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result = evaluator.evaluate(template, self.request)
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evaluator.set_policy_request(self.request)
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result = evaluator.evaluate(template)
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self.assertEqual(result.passing, False)
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self.assertEqual(result.messages, ("some message",))
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@ -31,7 +33,8 @@ class TestEvaluator(TestCase):
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"""test invalid syntax"""
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template = "{%"
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evaluator = Evaluator()
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result = evaluator.evaluate(template, self.request)
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evaluator.set_policy_request(self.request)
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result = evaluator.evaluate(template)
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self.assertEqual(result.passing, False)
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self.assertEqual(result.messages, ("tag name expected",))
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@ -39,7 +42,8 @@ class TestEvaluator(TestCase):
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"""test undefined result"""
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template = "{{ foo.bar }}"
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evaluator = Evaluator()
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result = evaluator.evaluate(template, self.request)
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evaluator.set_policy_request(self.request)
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result = evaluator.evaluate(template)
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self.assertEqual(result.passing, False)
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self.assertEqual(result.messages, ("'foo' is undefined",))
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