make [quiz|assignment].locked_for? vdd aware

fixes #CNVS-517
fixes #CNVS-761

test plan
- start with a course with students in different sections
- create a quiz with a lock date that locks the quiz currently
- create a lock date override that unlocks the quiz for one section
- ensure that a student from a section that the override does not apply to
  does see a lock icon on the course's quizzes list for the quiz
- ensure that a student from the section that the override does apply to
  does not see a lock icon on the course's quizzes list for the quiz

Change-Id: Ic1f553818ff106e1d29a8f1b66d8445b99aecffc
Reviewed-on: https://gerrit.instructure.com/16228
Tested-by: Jenkins <jenkins@instructure.com>
QA-Review: Marc LeGendre <marc@instructure.com>
Reviewed-by: Simon Williams <simon@instructure.com>

app/models/assignment.rb

@@ -731,14 +731,14 @@ class Assignment < ActiveRecord::Base
   end
 
   def locked_for?(user=nil, opts={})
-    locked = false
     return false if opts[:check_policies] && self.grants_right?(user, nil, :update)
     Rails.cache.fetch(locked_cache_key(user), :expires_in => 1.minute) do
       locked = false
-      if (self.unlock_at && self.unlock_at > Time.now)
-        locked = {:asset_string => self.asset_string, :unlock_at => self.unlock_at}
-      elsif (self.lock_at && self.lock_at <= Time.now)
-        locked = {:asset_string => self.asset_string, :lock_at => self.lock_at}
+      assignment_for_user = self.overridden_for(user)
+      if (assignment_for_user.unlock_at && assignment_for_user.unlock_at > Time.now)
+        locked = {:asset_string => self.asset_string, :unlock_at => assignment_for_user.unlock_at}
+      elsif (assignment_for_user.lock_at && assignment_for_user.lock_at <= Time.now)
+        locked = {:asset_string => self.asset_string, :lock_at => assignment_for_user.lock_at}
       elsif self.could_be_locked && item = locked_by_module_item?(user, opts[:deep_check_if_needed])
         locked = {:asset_string => self.asset_string, :context_module => item.context_module.attributes}
       end

app/models/quiz.rb

@@ -626,15 +626,16 @@ class Quiz < ActiveRecord::Base
     return false if opts[:check_policies] && self.grants_right?(user, nil, :update)
     Rails.cache.fetch(locked_cache_key(user), :expires_in => 1.minute) do
       locked = false
-      if (self.unlock_at && self.unlock_at > Time.now)
+      quiz_for_user = self.overridden_for(user)
+      if (quiz_for_user.unlock_at && quiz_for_user.unlock_at > Time.now)
         sub = user && quiz_submissions.find_by_user_id(user.id)
         if !sub || !sub.manually_unlocked
-          locked = {:asset_string => self.asset_string, :unlock_at => self.unlock_at}
+          locked = {:asset_string => self.asset_string, :unlock_at => quiz_for_user.unlock_at}
         end
-      elsif (self.lock_at && self.lock_at <= Time.now)
+      elsif (quiz_for_user.lock_at && quiz_for_user.lock_at <= Time.now)
         sub = user && quiz_submissions.find_by_user_id(user.id)
         if !sub || !sub.manually_unlocked
-          locked = {:asset_string => self.asset_string, :lock_at => self.lock_at}
+          locked = {:asset_string => self.asset_string, :lock_at => quiz_for_user.lock_at}
         end
       elsif (self.for_assignment? && l = self.assignment.locked_for?(user, opts))
         sub = user && quiz_submissions.find_by_user_id(user.id)

lib/assignment_override_applicator.rb

@@ -21,13 +21,14 @@ module AssignmentOverrideApplicator
   # version) and user, determine the list of overrides, apply them to the
   # assignment or quiz, and return the overridden stand-in.
   def self.assignment_overridden_for(assignment_or_quiz, user)
+    return assignment_or_quiz if user.nil? or assignment_or_quiz.overridden_for_user_id == user.id
+
     overrides = self.overrides_for_assignment_and_user(assignment_or_quiz, user)
-    
-    if overrides.empty?
-      assignment_or_quiz
-    else
-      self.assignment_with_overrides(assignment_or_quiz, overrides)
-    end
+ 
+    result_assignment_or_quiz = self.assignment_with_overrides(assignment_or_quiz, overrides) unless overrides.empty?
+    result_assignment_or_quiz ||= assignment_or_quiz
+    result_assignment_or_quiz.overridden_for_user_id = user.id
+    result_assignment_or_quiz
   end
 
   def self.quiz_overridden_for(quiz, user)

lib/dates_overridable.rb

@@ -1,6 +1,7 @@
 module DatesOverridable
   attr_accessor :applied_overrides
-  
+  attr_accessor :overridden_for_user_id
+
   def self.included(base)
     base.has_many :assignment_overrides, :dependent => :destroy
     base.has_many :active_assignment_overrides, :class_name => 'AssignmentOverride', :conditions => {:workflow_state => 'active'}
@@ -168,4 +169,4 @@ module DatesOverridable
 
     return as_student, as_instructor
   end
-end
+end

spec/lib/assignment_override_applicator_spec.rb

@@ -661,6 +661,46 @@ describe AssignmentOverrideApplicator do
     end
   end
 
+  describe "assignment_overridden_for" do
+    before :each do
+      student_in_course
+      @assignment = assignment_model(:course => @course)
+    end
+
+    it "should note the user id for whom overrides were applied" do
+      @adhoc_override = assignment_override_model(:assignment => @assignment)
+      @override_student = @adhoc_override.assignment_override_students.build
+      @override_student.user = @student
+      @override_student.save!
+      @adhoc_override.override_due_at(7.days.from_now)
+      @adhoc_override.save!
+      @overridden_assignment = AssignmentOverrideApplicator.assignment_overridden_for(@assignment, @student)
+      @overridden_assignment.overridden_for_user_id.should == @student.id
+    end
+
+    it "should note the user id for whom overrides were not found" do
+      @overridden_assignment = AssignmentOverrideApplicator.assignment_overridden_for(@assignment, @student)
+      @overridden_assignment.overridden_for_user_id.should == @student.id
+    end
+
+    it "should apply new overrides if an overridden assignment is overridden for a new user" do
+      @student1 = @student
+      @overridden_assignment = AssignmentOverrideApplicator.assignment_overridden_for(@assignment, @student1)
+      @overridden_assignment.overridden_for_user_id.should == @student1.id
+      student_in_course
+      @student2 = @student
+      AssignmentOverrideApplicator.expects(:overrides_for_assignment_and_user).with(@overridden_assignment, @student2).returns([])
+      @reoverridden_assignment = AssignmentOverrideApplicator.assignment_overridden_for(@overridden_assignment, @student2)
+    end
+
+    it "should not attempt to apply overrides if an overridden assignment is overridden for the same user" do
+      @overridden_assignment = AssignmentOverrideApplicator.assignment_overridden_for(@assignment, @student)
+      @overridden_assignment.overridden_for_user_id.should == @student.id
+      AssignmentOverrideApplicator.expects(:overrides_for_assignment_and_user).never
+      @reoverridden_assignment = AssignmentOverrideApplicator.assignment_overridden_for(@overridden_assignment, @student)
+    end
+  end
+
   it "should use the full stack" do
     student_in_course
     original_due_at = 3.days.from_now