Changed requirement structure generation to be function-based

 - Renamed some functions so they would make more sense.
 - Updated tests accordingly.
   - Added missing assert statement in
     `test_are_course_requirements_fulfilled`.

src/backend/csc_440_project_backend/grades/api.py

@@ -6,6 +6,7 @@
 
 from grades.models import Course, CourseInstance, GradeEntry, Category, CategoryScoreRequirement, Semester, \
     Requirement, College, Major, Concentration
+from grades.models.requirement import get_requirements_structure
 from grades.serializers import CourseSerializer, CourseInstanceSerializer, GradeEntrySerializer, CategorySerializer, \
     CollegeSerializer, CategoryScoreRequirementSerializer, SemesterSerializer, CourseInstanceSearchSerializer, \
     RequirementStructureSerializer, MajorSerializer, ConcentrationSerializer
@@ -203,7 +204,7 @@ def retrieve(self, request, *args, **kwargs):
         #     return Response(status=status.HTTP_404_NOT_FOUND)
         queryset = Requirement.objects.get(concentration_id=self.kwargs['pk'])
         # queryset = Requirement.objects.get(concentration_id=self.request.query_params['concentration'])
-        data = queryset.get_requirements_structure(self.request.user)
+        data = get_requirements_structure(queryset, self.request.user)
         serializer = RequirementStructureSerializer(data)
         return Response(serializer.data)
 

src/backend/csc_440_project_backend/grades/models/course.py

@@ -28,20 +28,22 @@ class Course(Common):
         default=False
     )
 
-    def is_completed(self, student):
-        """
-        Check if the course was completed by a student.
+    def __str__(self):
+        return f'{self.code}{", deprecated" if self.is_deprecated else ""}'
 
-        Notes:
-            TODO: This method should not be used. It is highly inefficient for course completion checking
 
-        Args:
-            student: Student to check
+def is_completed(course: Course, student):
+    """
+    Check if a course was completed by a student.
 
-        Returns:
-            Whether the student completed the course
-        """
-        return self.course_instances.filter(students=student).exists()
+    Notes:
+        TODO: This method should not be used. It is highly inefficient for course completion checking
 
-    def __str__(self):
-        return f'{self.code}{", deprecated" if self.is_deprecated else ""}'
+    Args:
+        course: Course instance
+        student: Student to check
+
+    Returns:
+        Whether the student completed the course
+    """
+    return course.course_instances.filter(students=student).exists()