Allow Enrollment API supports creating and upgrade course modes other than honor.

Fixing tests, cleaning up POST handler to be easier to read.

Wording fixed for unit test comments.

common/djangoapps/enrollment/views.py

@@ -6,6 +6,7 @@ consist primarily of authentication, request validation, and serialization.
 from ipware.ip import get_ip
 from django.utils.decorators import method_decorator
 from opaque_keys import InvalidKeyError
+from course_modes.models import CourseMode
 from openedx.core.djangoapps.user_api.preferences.api import update_email_opt_in
 from openedx.core.lib.api.permissions import ApiKeyHeaderPermission, ApiKeyHeaderPermissionIsAuthenticated
 from rest_framework import status
@@ -215,20 +216,27 @@ class EnrollmentListView(APIView, ApiKeyPermissionMixIn):
 
             2. Enroll the currently logged in user in a course.
 
-               Currently you can use this command only to enroll the user in "honor" mode.
+               Currently a user can use this command only to enroll the user in "honor" mode.
 
                If honor mode is not supported for the course, the request fails and returns the available modes.
 
+               A server-to-server call can be used by this command to enroll a user in other modes, such as "verified"
+                    or "professional". If the mode is not supposed for the course, the request will fail and return the
+                    available modes.
+
         **Example Requests**:
 
             GET /api/enrollment/v1/enrollment
 
-            POST /api/enrollment/v1/enrollment{"course_details":{"course_id": "edX/DemoX/Demo_Course"}}
+            POST /api/enrollment/v1/enrollment{"mode": "honor", "course_details":{"course_id": "edX/DemoX/Demo_Course"}}
 
         **Post Parameters**
 
             * user:  The user ID of the currently logged in user. Optional. You cannot use the command to enroll a different user.
 
+            * mode: The Course Mode for the enrollment. Individual users cannot upgrade their enrollment mode from
+                'honor'. Only server to server requests can enroll with other modes. Optional.
+
             * course details: A collection that contains:
 
                 * course_id: The unique identifier for the course.
@@ -302,13 +310,8 @@ class EnrollmentListView(APIView, ApiKeyPermissionMixIn):
         """
             Enrolls the currently logged in user in a course.
         """
+        # Get the User, Course ID, and Mode from the request.
         user = request.DATA.get('user', request.user.username)
-        if not user:
-            user = request.user.username
-        if user != request.user.username and not self.has_api_key_permissions(request):
-            # Return a 404 instead of a 403 (Unauthorized). If one user is looking up
-            # other users, do not let them deduce the existence of an enrollment.
-            return Response(status=status.HTTP_404_NOT_FOUND)
 
         if 'course_details' not in request.DATA or 'course_id' not in request.DATA['course_details']:
             return Response(
@@ -316,7 +319,6 @@ class EnrollmentListView(APIView, ApiKeyPermissionMixIn):
                 data={"message": u"Course ID must be specified to create a new enrollment."}
             )
         course_id = request.DATA['course_details']['course_id']
-
         try:
             course_id = CourseKey.from_string(course_id)
         except InvalidKeyError:
@@ -327,11 +329,33 @@ class EnrollmentListView(APIView, ApiKeyPermissionMixIn):
                 }
             )
 
+        mode = request.DATA.get('mode', CourseMode.HONOR)
+
+        has_api_key_permissions = self.has_api_key_permissions(request)
+
+        # Check that the user specified is either the same user, or this is a server-to-server request.
+        if not user:
+            user = request.user.username
+        if user != request.user.username and not has_api_key_permissions:
+            # Return a 404 instead of a 403 (Unauthorized). If one user is looking up
+            # other users, do not let them deduce the existence of an enrollment.
+            return Response(status=status.HTTP_404_NOT_FOUND)
+
+        if mode != CourseMode.HONOR and not has_api_key_permissions:
+            return Response(
+                status=status.HTTP_403_FORBIDDEN,
+                data={
+                    "message": u"User does not have permission to create enrollment with mode [{mode}].".format(
+                        mode=mode
+                    )
+                }
+            )
+
         # Check whether any country access rules block the user from enrollment
         # We do this at the view level (rather than the Python API level)
         # because this check requires information about the HTTP request.
         redirect_url = embargo_api.redirect_if_blocked(
-            course_id, user=request.user,
+            course_id, user=user,
             ip_address=get_ip(request),
             url=request.path
         )
@@ -347,12 +371,25 @@ class EnrollmentListView(APIView, ApiKeyPermissionMixIn):
             )
 
         try:
-            response = api.add_enrollment(user, unicode(course_id))
+            # Check if the user is currently enrolled, and if it is the same as the current enrolled mode. We do not
+            # have to check if it is inactive or not, because if it is, we are still upgrading if the mode is different,
+            # and either path will re-activate the enrollment.
+            #
+            # Only server-to-server calls will currently be allowed to modify the mode for existing enrollments. All
+            # other requests will go through add_enrollment(), which will allow creating of new enrollments, and
+            # re-activating enrollments
+            enrollment = api.get_enrollment(user, unicode(course_id))
+            if has_api_key_permissions and enrollment and enrollment['mode'] != mode:
+                response = api.update_enrollment(user, unicode(course_id), mode=mode)
+                http_success_status = status.HTTP_200_OK
+            else:
+                response = api.add_enrollment(user, unicode(course_id), mode=mode)
+                http_success_status = status.HTTP_201_CREATED
             email_opt_in = request.DATA.get('email_opt_in', None)
             if email_opt_in is not None:
                 org = course_id.org
                 update_email_opt_in(request.user, org, email_opt_in)
-            return Response(response)
+            return Response(response, status=http_success_status)
         except CourseModeNotFoundError as error:
             return Response(
                 status=status.HTTP_400_BAD_REQUEST,