fixed bug in certificate html view

Fixed bug: When certificate id previewed by a user who already has a
certificate generated with different mode it would not display
certificate in right preview mode.

lms/djangoapps/certificates/tests/test_webview_views.py

@@ -12,6 +12,7 @@ from django.test.utils import override_settings
 
 from openedx.core.lib.tests.assertions.events import assert_event_matches
 from student.tests.factories import UserFactory, CourseEnrollmentFactory
+from student.roles import CourseStaffRole
 from track.tests import EventTrackingTestCase
 from xmodule.modulestore.tests.factories import CourseFactory
 from xmodule.modulestore.tests.django_utils import ModuleStoreTestCase
@@ -346,6 +347,13 @@ class CertificatesViewsTests(ModuleStoreTestCase, EventTrackingTestCase):
             user_id=self.user.id,
             course_id=unicode(self.course.id)
         )
+        response = self.client.get(test_url + '?preview=honor')
+        #accessing certificate web view in preview mode without
+        # staff or instructor access should show invalid certificate
+        self.assertIn('This is an invalid certificate number', response.content)
+
+        CourseStaffRole(self.course.id).add_users(self.user)
+
         response = self.client.get(test_url + '?preview=honor')
         self.assertNotIn(self.course.display_name, response.content)
         self.assertIn('course_title_0', response.content)
@@ -358,6 +366,27 @@ class CertificatesViewsTests(ModuleStoreTestCase, EventTrackingTestCase):
         self.assertIn('course_title_0', response.content)
         self.assertIn('Signatory_Title 0', response.content)
 
+    @override_settings(FEATURES=FEATURES_WITH_CERTS_ENABLED)
+    def test_render_html_view_with_preview_mode_when_user_already_has_cert(self):
+        """
+        test certificate web view should render properly in
+        preview mode even if user who is previewing already has a certificate
+        generated with different mode.
+        """
+        self._add_course_certificates(count=1, signatory_count=2)
+        CourseStaffRole(self.course.id).add_users(self.user)
+
+        test_url = get_certificate_url(
+            user_id=self.user.id,
+            course_id=unicode(self.course.id)
+        )
+        # user has already has certificate generated for 'honor' mode
+        # so let's try to preview in 'verified' mode.
+        response = self.client.get(test_url + '?preview=verified')
+        self.assertNotIn(self.course.display_name, response.content)
+        self.assertIn('course_title_0', response.content)
+        self.assertIn('Signatory_Title 0', response.content)
+
     @override_settings(FEATURES=FEATURES_WITH_CERTS_ENABLED)
     def test_render_html_view_invalid_certificate_configuration(self):
         test_url = get_certificate_url(

lms/djangoapps/certificates/views/webview.py

@@ -14,6 +14,7 @@ from django.utils.translation import ugettext as _
 from django.core.urlresolvers import reverse
 
 from courseware.courses import course_image_url
+from courseware.access import has_access
 from edxmako.shortcuts import render_to_response
 from edxmako.template import Template
 from eventtracking import tracker
@@ -287,6 +288,7 @@ def render_html_view(request, user_id, course_id):
     context = {}
     context['platform_name'] = microsite.get_value("platform_name", settings.PLATFORM_NAME)
     context['course_id'] = course_id
+    preview_mode = request.GET.get('preview', None)
 
     # Update the view context with the default ConfigurationModel settings
     configuration = CertificateHtmlViewConfiguration.get_config()
@@ -334,17 +336,27 @@ def render_html_view(request, user_id, course_id):
             raise CourseDoesNotExist
 
         # Attempt to load the user's generated certificate data
-        user_certificate = GeneratedCertificate.objects.get(
-            user=user,
-            course_id=course_key
-        )
+        if preview_mode:
+            user_certificate = GeneratedCertificate.objects.get(
+                user=user,
+                course_id=course_key,
+                mode=preview_mode
+            )
+        else:
+            user_certificate = GeneratedCertificate.objects.get(
+                user=user,
+                course_id=course_key
+            )
 
     # If there's no generated certificate data for this user, we need to see if we're in 'preview' mode...
     # If we are, we'll need to create a mock version of the user_certificate container for previewing
     except GeneratedCertificate.DoesNotExist:
-        if request.GET.get('preview', None):
+        if preview_mode and (
+            has_access(request.user, 'instructor', course)
+            or has_access(request.user, 'staff', course)
+        ):
             user_certificate = GeneratedCertificate(
-                mode=request.GET.get('preview'),
+                mode=preview_mode,
                 verify_uuid=unicode(uuid4().hex),
                 modified_date=datetime.now().date()
             )
@@ -383,7 +395,7 @@ def render_html_view(request, user_id, course_id):
     # Get the active certificate configuration for this course
     # If we do not have an active certificate, we'll need to send the user to the "Invalid" screen
     # Passing in the 'preview' parameter, if specified, will return a configuration, if defined
-    active_configuration = get_active_web_certificate(course, request.GET.get('preview'))
+    active_configuration = get_active_web_certificate(course, preview_mode)
     if active_configuration is None:
         return render_to_response(invalid_template_path, context)
     else: