Reorganize reusable test code

Extract test views and user code into their own separate test case
mixins. Append TestCase to test case mixins with base test code
to differentiate them from test mixins with reusable view calls.

Signed-off-by: Roberto Rosario <Roberto.Rosario@mayan-edms.com>

mayan/apps/rest_api/permissions.py

@@ -3,6 +3,7 @@ from __future__ import absolute_import
 from __future__ import unicode_literals
 
 from django.core.exceptions import PermissionDenied
+from django.http import Http404
 
 from rest_framework.permissions import BasePermission
 
@@ -33,6 +34,10 @@ class MayanPermission(BasePermission):
             view, 'mayan_object_permissions', {}
         ).get(request.method, None)
 
+        object_permissions_raise_404 = getattr(
+            view, 'mayan_object_permissions_raise_404', ()
+        )
+
         if required_permission:
             try:
                 if hasattr(view, 'mayan_permission_attribute_check'):
@@ -47,7 +52,10 @@ class MayanPermission(BasePermission):
                         obj=obj
                     )
             except PermissionDenied:
-                return False
+                if request.method in object_permissions_raise_404:
+                    raise Http404
+                else:
+                    return False
             else:
                 return True
         else: