cast CRSid to lower case

identitylib/identifiers.py

@@ -325,6 +325,9 @@ class Identifier(namedtuple("Identifier", ["value", "scheme"])):
             raise ValueError(f"Invalid identifier {value}")
 
         parsed_value = scheme.value_parser(parsed_value) if scheme.value_parser else parsed_value
+
+        if str(scheme).lower() == str(IdentifierSchemes.CRSID).lower():
+            return Identifier(parsed_value.lower(), scheme)
         return Identifier(parsed_value, scheme)
 
     def __str__(self):

tests/test_identifiers.py

@@ -13,6 +13,12 @@ class IdentifiersTestCase(TestCase):
             Identifier("abc123", IdentifierSchemes.USN),
         )
 
+        # parsing CRSid cast to lower case
+        self.assertEqual(
+            Identifier.from_string("ABC123@v1.person.identifiers.cam.ac.uk"),
+            Identifier("abc123", IdentifierSchemes.CRSID),
+        )
+
         # fallback scheme given - actual scheme in identifier is used
         self.assertEqual(
             Identifier.from_string(