Added factory method and test of the same

src/saml2/authn_context/__init__.py

@@ -9,6 +9,12 @@
 PASSWORD = 'urn:oasis:names:tc:SAML:2.0:ac:classes:Password'
 TLSCLIENT = 'urn:oasis:names:tc:SAML:2.0:ac:classes:TLSClient'
 
+from saml2.authn_context import ippword
+from saml2.authn_context import mobiletwofactor
+from saml2.authn_context import ppt
+from saml2.authn_context import pword
+from saml2.authn_context import sslcert
+
 
 class Authn(object):
     def __init__(self):
@@ -68,4 +74,14 @@ def match(self, requested, provided):
         if requested == provided:
             return True
         else:
-            return False
+            return False
+
+
+def authn_context_factory(text):
+    # brute force
+    for mod in [ippword, mobiletwofactor, ppt, pword, sslcert]:
+        inst = mod.authentication_context_declaration_from_string(text)
+        if inst:
+            return inst
+
+    return None

tests/test_77_authn_context.py

@@ -12,7 +12,7 @@
 </AuthenticationContextDeclaration>"""
 
 from saml2.authn_context import pword
-
+from saml2.authn_context import authn_context_factory
 
 def test_passwd():
     length = pword.Length(min="4")
@@ -25,5 +25,12 @@ def test_passwd():
 
     assert inst == inst2
 
+
+def test_factory():
+    inst_pw = pword.authentication_context_declaration_from_string(ex1)
+    inst = authn_context_factory(ex1)
+
+    assert inst_pw == inst
+
 if __name__ == "__main__":
-    test_passwd()
+    test_factory()