✨(backend) allow IMS LIS LTI roles

When parsing LTI role string from requests, we want to handle IMS LIS
format.

CHANGELOG.md

@@ -8,6 +8,10 @@ Versioning](https://semver.org/spec/v2.0.0.html).
 
 ## [Unreleased]
 
+### Added
+
+- Support for the IMS LIS role format in the LTI launch
+
 ## [5.5.1] - 2024-11-29
 
 ### Fixed

src/backend/marsha/core/lti/__init__.py

@@ -264,6 +264,8 @@ def roles(self):
 
         """
         roles = self.request.POST.get("roles", "")
+        # remove LIS roles prefix
+        roles = re.sub(r"^urn:lti:instrole:ims/lis/", "", roles)
         # Remove all spaces from the string and extra trailing or leading commas
         roles = re.sub(r"[\s+]", "", roles).strip(",")
         # Return a set of the roles mentioned in the request

src/backend/marsha/core/tests/lti/tests.py

@@ -96,6 +96,7 @@ def test_lti_video_instructor(self):
             "student, Instructor",  # a space after the comma is allowed
             ", staff",  # a leading comma should be ignored
             "staff,",  # a trailing comma should be ignored
+            "urn:lti:instrole:ims/lis/Instructor",  # the LIS role identifier should be recognized
         ]:
             request = self.factory.post("/", {"roles": roles_string})
             lti = LTI(request, uuid.uuid4())