Take both a list of strings and comma separated string in get_roles

LTI1.1 provides a comma separated list of roles while LTI1.3 provides a
list.

The launch LTIParams provides an abstraction for this, always returning
the LTI1.1 version.

To allow using get_roles outside a launch context without having to
needlessly convert between the two formats allow the method to take
roles in both formats.

lms/services/lti_role_service.py

@@ -11,15 +11,17 @@ class LTIRoleService:
     def __init__(self, db_session: Session):
         self._db = db_session
 
-    def get_roles(self, role_description: str) -> list[LTIRole]:
+    def get_roles(self, role_description: str | list[str]) -> list[LTIRole]:
         """
         Get a list of role objects for the provided strings.
 
-        :param role_description: A comma delimited set of role strings
+        :param role_description: A comma delimited set of role strings for LTI1.1 or a list of string for LTI1.3
         """
-        role_strings = [role.strip() for role in role_description.split(",")]
+        if isinstance(role_description, str):
+            role_strings = [role.strip() for role in role_description.split(",")]
+        else:
+            role_strings = role_description
 
-        # Pylint is confused about the `in_` for some reason
         roles = self._db.query(LTIRole).filter(LTIRole.value.in_(role_strings)).all()
 
         for role in roles:

tests/unit/lms/services/lti_role_service_test.py

@@ -10,7 +10,8 @@
 
 
 class TestLTIRoleService:
-    def test_get_roles(self, svc, existing_roles):
+    @pytest.mark.parametrize("roles_as_string", [True, False])
+    def test_get_roles(self, svc, existing_roles, roles_as_string):
         existing_role_strings = [role.value for role in existing_roles]
         new_roles = [
             "http://purl.imsglobal.org/vocab/lis/v2/system/person#SysSupport",
@@ -22,7 +23,9 @@ def test_get_roles(self, svc, existing_roles):
         role_descriptions.append(existing_roles[0].value)
         role_descriptions.extend(new_roles)
 
-        roles = svc.get_roles(", ".join(role_descriptions))
+        if roles_as_string:
+            role_descriptions = ", ".join(role_descriptions)
+        roles = svc.get_roles(role_descriptions)
 
         expected_new_roles = [
             Any.instance_of(LTIRole).with_attrs({"value": value}) for value in new_roles