Merge pull request #22425 from edx/dsheraz/PROD-1055

create CSM service

lms/djangoapps/courseware/services.py

+"""
+Courseware services.
+"""
+from __future__ import absolute_import
+
+import json
+
+from lms.djangoapps.courseware.models import StudentModule
+
+
+class UserStateService(object):
+    """
+    User state service to make state accessible in runtime.
+    """
+
+    def get_state_as_dict(self, username, block_id):
+        """
+        Return dict containing user state for a given set of parameters.
+
+        Arguments:
+            username: username of the user for whom the data is being retrieved
+            block_id: string/object representation of the block whose user state is required
+
+        Returns:
+            Returns a dict containing user state, if present, else empty.
+        """
+        try:
+            student_module = StudentModule.objects.get(
+                student__username=username,
+                module_state_key=block_id
+            )
+            return json.loads(student_module.state)
+        except StudentModule.DoesNotExist:
+            return {}

lms/djangoapps/courseware/tests/test_services.py

+"""
+Tests for courseware services.
+"""
+from __future__ import absolute_import
+
+import json
+
+import ddt
+
+from lms.djangoapps.courseware.services import UserStateService
+from lms.djangoapps.courseware.tests.factories import StudentModuleFactory, UserFactory
+from xmodule.modulestore.tests.django_utils import ModuleStoreTestCase
+from xmodule.modulestore.tests.factories import CourseFactory, ItemFactory
+
+
+@ddt.ddt
+class TestUserStateService(ModuleStoreTestCase):
+    """
+    Test suite for user state service.
+    """
+
+    def setUp(self):
+        """
+        Creating pre-requisites for the test cases.
+        """
+        super(TestUserStateService, self).setUp()
+        self.user = UserFactory.create()
+        self.course = CourseFactory.create()
+        chapter = ItemFactory.create(
+            category='chapter',
+            parent=self.course,
+            display_name='Test Chapter'
+        )
+        sequential = ItemFactory.create(
+            category='sequential',
+            parent=chapter,
+            display_name='Test Sequential'
+        )
+        vertical = ItemFactory.create(
+            category='vertical',
+            parent=sequential,
+            display_name='Test Vertical'
+        )
+        self.problem = ItemFactory.create(
+            category='problem',
+            parent=vertical,
+            display_name='Test Problem'
+        )
+
+    def _create_student_module(self, state):
+        StudentModuleFactory.create(
+            student=self.user,
+            module_state_key=self.problem.location,
+            course_id=self.course.id,
+            state=json.dumps(state)
+        )
+
+    @ddt.data(
+        ({'key_1a': 'value_1a', 'key_2a': 'value_2a'}),
+        ({'key_1b': 'value_1b', 'key_2b': 'value_2b', 'key_3b': 'value_3b'})
+    )
+    def test_student_state(self, expected_state):
+        """
+        Verify the service gets the correct state from the student module.
+
+        Scenario:
+            Given a user and a problem or block
+            Then create a student module entry for the user
+            If the state is obtained from student module service
+            Then the state is equal to previously created student module state
+        """
+        self._create_student_module(expected_state)
+        state = UserStateService().get_state_as_dict(
+            self.user.username, self.problem.location
+        )
+        self.assertDictEqual(state, expected_state)
+
+    @ddt.data(
+        ({'username': 'no_user', 'block_id': 'block-v1:myOrg+1234+2030_T2+type@openassessment+block@hash'}),
+        ({'username': 'no_user'}),
+        ({'block_id': 'block-v1:myOrg+1234+2030_T2+type@openassessment+block@hash'})
+    )
+    def test_nonexistent_student_module_state(self, state_params):
+        """
+        Verify the user state service returns empty dict for non-existent student module entry.
+
+        Scenario:
+            Given a user and a problem/block
+            Then create a student module entry for the user
+            If the state is obtained with incorrect parameters
+            Then an empty dict is returned
+        """
+        params = {
+            'username': self.user.username,
+            'block_id': self.problem.location
+        }
+        params.update(state_params)
+        self._create_student_module({'key_1': 'value_1'})
+        state = UserStateService().get_state_as_dict(**params)
+        self.assertFalse(state)