Merge pull request #563 from erakli/fix_response_condition_check

Fix AuthnResponse.condition_ok to not require conditions

## 2.3.3 Element <Assertion>
The <Assertion> element is of the `AssertionType` complex type. This type specifies the basic
information that is common to all assertions, including the following elements and attributes:

### <Conditions> [Optional]
Conditions that MUST be evaluated when assessing the validity of and/or when using the assertion.
See _Section 2.5_ for additional information on how to evaluate conditions

Author: c00kiemon5ter

src/saml2/response.py

@@ -569,11 +569,14 @@ def authn_statement_ok(self, optional=False):
         # check authn_statement.session_index
 
     def condition_ok(self, lax=False):
+        if not self.assertion.conditions:
+            # Conditions is Optional for Assertion, so, if it's absent, then we
+            # assume that its valid
+            return True
+
         if self.test:
             lax = True
 
-        # The Identity Provider MUST include a <saml:Conditions> element
-        assert self.assertion.conditions
         conditions = self.assertion.conditions
 
         logger.debug("conditions: %s", conditions)