-changed method name from "from_string_or_404" to "course_key_from_string_or_404".

-Updated method "course_key_from_string_or_404" to raise message too.
-Wrote tests for "course_key_from_string_or_404" when exception message is given.
-Modified existing methods to use "ddt.data".
-Used Splunk logs to find exectly where we were getting "Invalid Key Error"
-Updated Views where we were getting "Invalid Key Error" in splunk logs.
-Wrote tests for those View End points where we were getting "Invalid Key Error"

cms/djangoapps/contentstore/views/tabs.py

@@ -14,7 +14,8 @@ from edxmako.shortcuts import render_to_response
 from xmodule.modulestore.django import modulestore
 from xmodule.modulestore import ModuleStoreEnum
 from xmodule.tabs import CourseTabList, CourseTab, InvalidTabsException, StaticTab
-from opaque_keys.edx.keys import CourseKey, UsageKey
+from opaque_keys.edx.keys import UsageKey
+from util.course_key_utils import course_key_from_string_or_404
 
 from ..utils import get_lms_link_for_item
 
@@ -39,7 +40,7 @@ def tabs_handler(request, course_key_string):
     Creating a tab, deleting a tab, or changing its contents is not supported through this method.
     Instead use the general xblock URL (see item.xblock_handler).
     """
-    course_key = CourseKey.from_string(course_key_string)
+    course_key = course_key_from_string_or_404(course_key_string)
     if not has_course_author_access(request.user, course_key):
         raise PermissionDenied()
 

cms/djangoapps/contentstore/views/tests/test_tabs.py

@@ -10,6 +10,7 @@ from xmodule.modulestore.tests.factories import CourseFactory, ItemFactory
 from xmodule.modulestore.tests.django_utils import ModuleStoreTestCase
 from xmodule.tabs import CourseTabList
 from xmodule.modulestore.django import modulestore
+from django.http import Http404
 
 
 class TabsPageTests(CourseTestCase):
@@ -191,6 +192,13 @@ class TabsPageTests(CourseTestCase):
         self.assertIn('<span class="sr">Delete this component</span>', html)
         self.assertIn('<span data-tooltip="Drag to reorder" class="drag-handle action"></span>', html)
 
+    def test_invalid_course_id(self):
+        """ Asserts that Http404 is raised when the course id is not valid. """
+        invalid_tab_url = reverse_course_url('tabs_handler', "/some.invalid.key/TTT/CS01/2015_T0")
+        with self.assertRaises(Http404):
+            self.client.get(invalid_tab_url)
+
+
 
 class PrimitiveTabEdit(ModuleStoreTestCase):
     """Tests for the primitive tab edit data manipulations"""

cms/djangoapps/contentstore/views/tests/test_user.py

@@ -9,6 +9,7 @@ from django.contrib.auth.models import User
 from student.models import CourseEnrollment
 from student.roles import CourseStaffRole, CourseInstructorRole
 from student import auth
+from django.http import Http404
 
 
 class UsersTestCase(CourseTestCase):
@@ -315,3 +316,12 @@ class UsersTestCase(CourseTestCase):
             CourseEnrollment.is_enrolled(self.ext_user, self.course.id),
             'User ext_user should have been enrolled in the course'
         )
+
+    def test_invalid_course_id(self):
+        """ Asserts that Http404 is raised when the course id is not valid. """
+        wrong_url = reverse_course_url(
+            'course_team_handler', "/some.invalid.key/TTT/CS01/2015_T0",
+            kwargs={'email': self.ext_user.email}
+        )
+        with self.assertRaises(Http404):
+            self.client.get(wrong_url)

cms/djangoapps/contentstore/views/user.py

@@ -8,7 +8,7 @@ from django.views.decorators.csrf import ensure_csrf_cookie
 from edxmako.shortcuts import render_to_response
 
 from xmodule.modulestore.django import modulestore
-from opaque_keys.edx.keys import CourseKey
+from util.course_key_utils import course_key_from_string_or_404
 from opaque_keys.edx.locator import LibraryLocator
 from util.json_request import JsonResponse, expect_json
 from student.roles import CourseInstructorRole, CourseStaffRole, LibraryUserRole
@@ -49,7 +49,7 @@ def course_team_handler(request, course_key_string=None, email=None):
     DELETE:
         json: remove a particular course team member from the course team (email is required).
     """
-    course_key = CourseKey.from_string(course_key_string) if course_key_string else None
+    course_key = course_key_from_string_or_404(course_key_string) if course_key_string else None
     # No permissions check here - each helper method does its own check.
 
     if 'application/json' in request.META.get('HTTP_ACCEPT', 'application/json'):

common/djangoapps/util/course_key_utils.py

@@ -6,14 +6,15 @@ from opaque_keys import InvalidKeyError
 from opaque_keys.edx.keys import CourseKey
 
 
-def from_string_or_404(course_key_string):
+def course_key_from_string_or_404(course_key_string, message=None):
     """
     Gets CourseKey from the string passed as parameter.
 
     Parses course key from string(containing course key) or raises 404 if the string's format is invalid.
 
     Arguments:
-        course_key_string(str): It is string containing the course key
+        course_key_string(str): It contains the course key
+        message(str): It contains the exception message
 
     Returns:
         CourseKey: A key that uniquely identifies a course
@@ -25,6 +26,6 @@ def from_string_or_404(course_key_string):
     try:
         course_key = CourseKey.from_string(course_key_string)
     except InvalidKeyError:
-        raise Http404
+        raise Http404(message)
 
-    return course_key
+    return course_key
\ No newline at end of file

common/djangoapps/util/tests/test_course_key_utils.py

 """
 Tests for util.course_key_utils
 """
-from nose.tools import assert_equals, assert_raises  # pylint: disable=no-name-in-module
-from util.course_key_utils import from_string_or_404
+from util.course_key_utils import course_key_from_string_or_404
 from opaque_keys.edx.keys import CourseKey
 from django.http import Http404
+import ddt
+import unittest
 
 
-def test_from_string_or_404():
-
-    #testing with split style course keys
-    assert_raises(
-        Http404,
-        from_string_or_404,
-        "/some.invalid.key/course-v1:TTT+CS01+2015_T0"
-    )
-    assert_equals(
-        CourseKey.from_string("course-v1:TTT+CS01+2015_T0"),
-        from_string_or_404("course-v1:TTT+CS01+2015_T0")
+@ddt.ddt
+class TestFromStringOr404(unittest.TestCase):
+    """
+    Base Test class for course_key_from_string_or_404 utility tests
+    """
+    @ddt.data(
+        ("/some.invalid.key/course-v1:TTT+CS01+2015_T0", "course-v1:TTT+CS01+2015_T0"),  # split style course keys
+        ("/some.invalid.key/TTT/CS01/2015_T0", "TTT/CS01/2015_T0"),  # mongo style course keys
     )
+    def test_from_string_or_404(self, (invalid_course_key, valid_course_key)):
+        """
+        Tests course_key_from_string_or_404 for valid and invalid split style course keys and mongo style course keys.
+        """
+        self.assertRaises(
+            Http404,
+            course_key_from_string_or_404,
+            invalid_course_key,
+        )
+        self.assertEquals(
+            CourseKey.from_string(valid_course_key),
+            course_key_from_string_or_404(valid_course_key)
+        )
 
-    #testing with mongo style course keys
-    assert_raises(
-        Http404,
-        from_string_or_404,
-        "/some.invalid.key/TTT/CS01/2015_T0"
-    )
-    assert_equals(
-        CourseKey.from_string("TTT/CS01/2015_T0"),
-        from_string_or_404("TTT/CS01/2015_T0")
+    @ddt.data(
+        "/some.invalid.key/course-v1:TTT+CS01+2015_T0",  # split style invalid course key
+        "/some.invalid.key/TTT/CS01/2015_T0"  # mongo style invalid course key
     )
+    def test_from_string_or_404_with_message(self, course_string):
+        """
+        Tests course_key_from_string_or_404 with exception message for split style and monog style invalid course keys.
+        :return:
+        """
+        try:
+            course_key_from_string_or_404(course_string, message="Invalid Keys")
+        except Http404 as exception:
+            self.assertEquals(str(exception), "Invalid Keys")
\ No newline at end of file

lms/djangoapps/django_comment_client/forum/tests.py

@@ -1312,6 +1312,14 @@ class InlineDiscussionUnicodeTestCase(SharedModuleStoreTestCase, UnicodeTestMixi
         self.assertEqual(response_data["discussion_data"][0]["title"], text)
         self.assertEqual(response_data["discussion_data"][0]["body"], text)
 
+    def _test_invalid_course_id(self):
+        """ Asserts that Http404 is raised when the course id is not valid. """
+        request = RequestFactory().get("dummy_url")
+        request.user = self.student
+        with self.assertRaises(Http404):
+            views.inline_discussion(
+                request, self.course.id.to_deprecated_string(), self.course.discussion_topics['General']['id']
+        )
 
 class ForumFormDiscussionUnicodeTestCase(SharedModuleStoreTestCase, UnicodeTestMixin):
     @classmethod

lms/djangoapps/django_comment_client/forum/views.py

@@ -40,7 +40,7 @@ from django_comment_client.utils import (
 import django_comment_client.utils as utils
 import lms.lib.comment_client as cc
 
-from opaque_keys.edx.keys import CourseKey
+from util.course_key_utils import course_key_from_string_or_404
 
 THREADS_PER_PAGE = 20
 INLINE_THREADS_PER_PAGE = 20
@@ -178,7 +178,7 @@ def use_bulk_ops(view_func):
     """
     @wraps(view_func)
     def wrapped_view(request, course_id, *args, **kwargs):  # pylint: disable=missing-docstring
-        course_key = CourseKey.from_string(course_id)
+        course_key = course_key_from_string_or_404(course_id)
         with modulestore().bulk_operations(course_key):
             return view_func(request, course_key, *args, **kwargs)
     return wrapped_view