Add beta test group support

* add a days_early_for_beta inherited policy option
* students in the beta_testers_{COURSE} group get to see content that many days early
* Clean up some docstrings related to time formats
* Add basic test

common/lib/xmodule/xmodule/timeparse.py

@@ -7,8 +7,11 @@ TIME_FORMAT = "%Y-%m-%dT%H:%M"
 
 def parse_time(time_str):
     """
-    Takes a time string in TIME_FORMAT, returns
-    it as a time_struct.  Raises ValueError if the string is not in the right format.
+    Takes a time string in TIME_FORMAT
+
+    Returns it as a time_struct.
+
+    Raises ValueError if the string is not in the right format.
     """
     return time.strptime(time_str, TIME_FORMAT)
 

common/lib/xmodule/xmodule/x_module.py

@@ -414,7 +414,11 @@ class XModuleDescriptor(Plugin, HTMLSnippet, ResourceTemplates):
         'xqa_key',
         # TODO: This is used by the XMLModuleStore to provide for locations for
         # static files, and will need to be removed when that code is removed
-        'data_dir'
+        'data_dir',
+        # How many days early to show a course element to beta testers (float)
+        # intended to be set per-course, but can be overridden in for specific
+        # elements.  Can be a float.
+        'days_early_for_beta'
     )
 
     # cdodge: this is a list of metadata names which are 'system' metadata
@@ -497,13 +501,24 @@ class XModuleDescriptor(Plugin, HTMLSnippet, ResourceTemplates):
     @property
     def start(self):
         """
-        If self.metadata contains start, return it.  Else return None.
+        If self.metadata contains a valid start time, return it as a time struct.
+        Else return None.
         """
         if 'start' not in self.metadata:
             return None
         return self._try_parse_time('start')
 
     @property
+    def days_early_for_beta(self):
+        """
+        If self.metadata contains start, return the number, as a float.  Else return None.
+        """
+        if 'days_early_for_beta' not in self.metadata:
+            return None
+        return float(self.metadata['days_early_for_beta'])
+
+
+    @property
     def own_metadata(self):
         """
         Return the metadata that is not inherited, but was defined on this module.
@@ -715,7 +730,8 @@ class XModuleDescriptor(Plugin, HTMLSnippet, ResourceTemplates):
         """
         Parse an optional metadata key containing a time: if present, complain
         if it doesn't parse.
-        Return None if not present or invalid.
+        
+        Returns a time_struct, or None if metadata key is not present or is invalid.
         """
         if key in self.metadata:
             try:

doc/xml-format.md

@@ -257,6 +257,7 @@ Supported fields at the course level:
 * "tabs" -- have custom tabs in the courseware.  See below for details on config.
 * "discussion_blackouts" -- An array of time intervals during which you want to disable a student's ability to create or edit posts in the forum. Moderators, Community TAs, and Admins are unaffected. You might use this during exam periods, but please be aware that the forum is often a very good place to catch mistakes and clarify points to students. The better long term solution would be to have better flagging/moderation mechanisms, but this is the hammer we have today. Format by example: [["2012-10-29T04:00", "2012-11-03T04:00"], ["2012-12-30T04:00", "2013-01-02T04:00"]]
 * "show_calculator" (value "Yes" if desired)
+* "days_early_for_beta" -- number of days early that students in the beta-testers group get to see course content.  Can also be specified for any other course element, and overrides values set at higher levels.
 * TODO: there are others
 
 ### Grading policy file contents

lms/djangoapps/courseware/access.py

@@ -4,13 +4,13 @@ like DISABLE_START_DATES"""
 
 import logging
 import time
+from datetime import datetime, timedelta
 
 from django.conf import settings
 
 from xmodule.course_module import CourseDescriptor
 from xmodule.error_module import ErrorDescriptor
 from xmodule.modulestore import Location
-from xmodule.timeparse import parse_time
 from xmodule.x_module import XModule, XModuleDescriptor
 
 from student.models import CourseEnrollmentAllowed
@@ -73,7 +73,7 @@ def has_access(user, obj, action):
     raise TypeError("Unknown object type in has_access(): '{0}'"
                     .format(type(obj)))
 
-def get_access_group_name(obj,action):
+def get_access_group_name(obj, action):
     '''
     Returns group name for user group which has "action" access to the given object.
 
@@ -226,9 +226,10 @@ def _has_access_descriptor(user, descriptor, action):
         # Check start date
         if descriptor.start is not None:
             now = time.gmtime()
-            if now > descriptor.start:
+            effective_start = _adjust_start_date_for_beta_testers(user, descriptor)
+            if now > effective_start:
                 # after start date, everyone can see it
-                debug("Allow: now > start date")
+                debug("Allow: now > effective start date")
                 return True
             # otherwise, need staff access
             return _has_staff_access_to_descriptor(user, descriptor)
@@ -328,6 +329,15 @@ def _course_staff_group_name(location):
     """
     return 'staff_%s' % Location(location).course
 
+def _course_beta_test_group_name(location):
+    """
+    Get the name of the beta tester group for a location.  Right now, that's
+    beta_testers_COURSE.
+
+    location: something that can passed to Location.
+    """
+    return 'beta_testers_{0}'.format(Location(location).course)
+
 
 def _course_instructor_group_name(location):
     """
@@ -348,6 +358,46 @@ def _has_global_staff_access(user):
         return False
 
 
+def _adjust_start_date_for_beta_testers(user, descriptor):
+    """
+    If user is in a beta test group, adjust the start date by the appropriate number of
+    days.
+
+    Arguments:
+       user: A django user.  May be anonymous.
+       descriptor: the XModuleDescriptor the user is trying to get access to, with a
+       non-None start date.
+
+    Returns:
+        A time, in the same format as returned by time.gmtime().  Either the same as
+        start, or earlier for beta testers.
+
+    NOTE: number of days to adjust should be cached to avoid looking it up thousands of
+    times per query.
+
+    NOTE: For now, this function assumes that the descriptor's location is in the course
+    the user is looking at.  Once we have proper usages and definitions per the XBlock
+    design, this should use the course the usage is in.
+    """
+    if descriptor.days_early_for_beta is None:
+        # bail early if no beta testing is set up
+        return descriptor.start
+
+    user_groups = [g.name for g in user.groups.all()]
+
+    beta_group = _course_beta_test_group_name(descriptor.location)
+    if beta_group in user_groups:
+        debug("Adjust start time: user in group %s", beta_group)
+        # time_structs don't support subtraction, so convert to datetimes,
+        # subtract, convert back.
+        start_as_datetime = datetime(*descriptor.start[:6])
+        delta = timedelta(descriptor.days_early_for_beta)
+        effective = start_as_datetime - delta
+        # ...and back to time_struct
+        return effective.timetuple()
+
+    return descriptor.start
+
 def _has_instructor_access_to_location(user, location):
     return _has_access_to_location(user, location, 'instructor')
 

lms/djangoapps/courseware/tests/tests.py

@@ -17,7 +17,8 @@ import xmodule.modulestore.django
 
 # Need access to internal func to put users in the right group
 from courseware import grades
-from courseware.access import _course_staff_group_name
+from courseware.access import (has_access, _course_staff_group_name,
+                               _course_beta_test_group_name)
 from courseware.models import StudentModuleCache
 
 from student.models import Registration
@@ -453,6 +454,9 @@ class TestViewAuth(PageLoader):
         """Check that enrollment periods work"""
         self.run_wrapped(self._do_test_enrollment_period)
 
+    def test_beta_period(self):
+        """Check that beta-test access works"""
+        self.run_wrapped(self._do_test_beta_period)
 
     def _do_test_dark_launch(self):
         """Actually do the test, relying on settings to be right."""
@@ -618,6 +622,38 @@ class TestViewAuth(PageLoader):
         self.unenroll(self.toy)
         self.assertTrue(self.try_enroll(self.toy))
 
+    def _do_test_beta_period(self):
+        """Actually test beta periods, relying on settings to be right."""
+
+        # trust, but verify :)
+        self.assertFalse(settings.MITX_FEATURES['DISABLE_START_DATES'])
+
+        # Make courses start in the future
+        tomorrow = time.time() + 24 * 3600
+        nextday = tomorrow + 24 * 3600
+        yesterday = time.time() - 24 * 3600
+
+        # toy course's hasn't started
+        self.toy.metadata['start'] = stringify_time(time.gmtime(tomorrow))
+        self.assertFalse(self.toy.has_started())
+
+        # but should be accessible for beta testers
+        self.toy.metadata['days_early_for_beta'] = '2'
+
+        # student user shouldn't see it
+        student_user = user(self.student)
+        self.assertFalse(has_access(student_user, self.toy, 'load'))
+
+        # now add the student to the beta test group
+        group_name = _course_beta_test_group_name(self.toy.location)
+        g = Group.objects.create(name=group_name)
+        g.user_set.add(student_user)
+
+        # now the student should see it
+        self.assertTrue(has_access(student_user, self.toy, 'load'))
+
+
+
 @override_settings(MODULESTORE=TEST_DATA_XML_MODULESTORE)
 class TestCourseGrader(PageLoader):
     """Check that a course gets graded properly"""