From 49988101b244091605bc211ee34ee4ddf81bee63 Mon Sep 17 00:00:00 2001
From: cp-at-mit <collinp@mit.edu>
Date: Mon, 5 Aug 2024 13:44:22 -0400
Subject: [PATCH] Add prerequisites to courses API (#2321)

Co-authored-by: pre-commit-ci[bot] <66853113+pre-commit-ci[bot]@users.noreply.github.com>
---
 courses/serializers/v2/courses.py      | 14 ++++++++++
 courses/serializers/v2/courses_test.py | 36 ++++++++++++++++++++++++++
 2 files changed, 50 insertions(+)

diff --git a/courses/serializers/v2/courses.py b/courses/serializers/v2/courses.py
index d099bc08e8..6ea3ddf47c 100644
--- a/courses/serializers/v2/courses.py
+++ b/courses/serializers/v2/courses.py
@@ -32,6 +32,19 @@ class CourseSerializer(BaseCourseSerializer):
     programs = serializers.SerializerMethodField()
     topics = serializers.SerializerMethodField()
     certificate_type = serializers.SerializerMethodField()
+    required_prerequisites = serializers.SerializerMethodField()
+
+    def get_required_prerequisites(self, instance):
+        """
+        Check if the prerequisites field is populated in the course page CMS.
+        Returns:
+            bool: True when the prerequisites field is populated in the course page CMS.  False otherwise.
+        """
+        return bool(
+            hasattr(instance, "page")
+            and hasattr(instance.page, "prerequisites")
+            and instance.page.prerequisites != ""
+        )
 
     def get_next_run_id(self, instance):
         """Get next run id"""
@@ -74,6 +87,7 @@ class Meta:
             "programs",
             "topics",
             "certificate_type",
+            "required_prerequisites",
         ]
 
 
diff --git a/courses/serializers/v2/courses_test.py b/courses/serializers/v2/courses_test.py
index 538f4bf522..d5530e0a38 100644
--- a/courses/serializers/v2/courses_test.py
+++ b/courses/serializers/v2/courses_test.py
@@ -3,6 +3,7 @@
 
 from cms.serializers import CoursePageSerializer
 from courses.factories import (
+    CourseFactory,
     CourseRunEnrollmentFactory,
     CourseRunFactory,
     ProgramFactory,
@@ -66,8 +67,43 @@ def test_serialize_course(
             "page": CoursePageSerializer(course.page).data,
             "certificate_type": certificate_type,
             "topics": [{"name": topic.name} for topic in topics],
+            "required_prerequisites": True,
             "programs": BaseProgramSerializer(course.programs, many=True).data
             if all_runs
             else None,
         },
     )
+
+
+@pytest.mark.parametrize("prerequisites_cms_value", ["mock value", None, ""])
+def test_serialize_course_required_prerequisites(
+    mocker, mock_context, prerequisites_cms_value, settings
+):
+    """Test Course serialization to ensure that required_prerequisites is set to True if prerequisites is defined in the CMS and no an empty string, otherwise False"""
+    course = CourseFactory.create()
+    expected_required_prerequisites = False
+    if prerequisites_cms_value is not None:
+        # When prerequisites_cms_value is None, the course page has been created but prerequisites has never been populated.
+        # If the prerequisites have previously been populated but are now empty, the value of prerequisites will be an empty string.
+        course.page.prerequisites = prerequisites_cms_value
+    if prerequisites_cms_value != "":
+        expected_required_prerequisites = True
+
+    data = CourseWithCourseRunsSerializer(instance=course, context=mock_context).data
+
+    assert_drf_json_equal(
+        data,
+        {
+            "title": course.title,
+            "readable_id": course.readable_id,
+            "id": course.id,
+            "courseruns": [],
+            "next_run_id": None,
+            "departments": [],
+            "page": CoursePageSerializer(course.page).data,
+            "certificate_type": "Certificate of Completion",
+            "topics": [],
+            "required_prerequisites": expected_required_prerequisites,
+            "programs": None,
+        },
+    )