makes assignments unavailable in availability gaps

Prevents a student from being able to submit assignments when they are
in between availability windows for an assignment, ex: when they're in a
section that had already completed and in a section that has not yet
started.

fixes CNVS-24849

test plan:
- make sure students in a section where an assigment is available can
  still submit assignments
- make sure students see when their assignment will be available if
  their availability window has not yet started
- make sure students see when their assignment was last available if
  their availablility window has already ended
- make sure students see when their assignment will be available if
  they're in a gap between availability windows

Change-Id: Ia2d9aa6f9a694b4c6cd434e93c1b3156d437c198
Reviewed-on: https://gerrit.instructure.com/80843
Reviewed-by: Davis McClellan <dmcclellan@instructure.com>
Tested-by: Jenkins
QA-Review: Michael Hargiss <mhargiss@instructure.com>
Product-Review: Jason Sparks <jsparks@instructure.com>

Author: Ben Rinaca

app/models/assignment_override.rb

@@ -231,6 +231,12 @@ def lock_at=(new_lock_at)
     write_attribute(:lock_at, CanvasTime.fancy_midnight(new_lock_at))
   end
 
+  def availability_expired?
+    lock_at_overridden &&
+      lock_at.present? &&
+      lock_at <= Time.zone.now
+  end
+
   def as_hash
     { :title => title,
       :due_at => due_at,

lib/assignment_override_applicator.rb

@@ -319,9 +319,13 @@ def self.overridden_all_day_date(assignment, overrides)
 
   def self.overridden_unlock_at(assignment_or_quiz, overrides)
     applicable_overrides = overrides.select(&:unlock_at_overridden)
+
+    # CNVS-24849 if the override has been locked it's unlock_at no longer applies
+    applicable_overrides.reject!(&:availability_expired?)
+
     if applicable_overrides.empty?
       assignment_or_quiz.unlock_at
-    elsif override = applicable_overrides.detect{ |o| o.unlock_at.nil? }
+    elsif applicable_overrides.any? { |o| o.unlock_at.nil? }
       nil
     else
       applicable_overrides.sort_by(&:unlock_at).first.unlock_at
@@ -332,7 +336,7 @@ def self.overridden_lock_at(assignment_or_quiz, overrides)
     applicable_overrides = overrides.select(&:lock_at_overridden)
     if applicable_overrides.empty?
       assignment_or_quiz.lock_at
-    elsif override = applicable_overrides.detect{ |o| o.lock_at.nil? }
+    elsif applicable_overrides.detect{ |o| o.lock_at.nil? }
       nil
     else
       applicable_overrides.sort_by(&:lock_at).last.lock_at

spec/lib/assignment_override_applicator_spec.rb

@@ -773,6 +773,25 @@ def setup_overridden_assignments(section_due_at, assignment_due_at)
       expect(@overridden.association(:rubric).loaded?).to eq @assignment.association(:rubric).loaded?
       @overridden.learning_outcome_alignments.loaded? == @assignment.learning_outcome_alignments.loaded?
     end
+
+    it "should be locked in between overrides" do
+      past_override = assignment_override_model(assignment: @assignment,
+                                                unlock_at: 2.months.ago,
+                                                lock_at: 1.month.ago)
+      future_override = assignment_override_model(assignment: @assignment,
+                                                  unlock_at: 2.months.from_now,
+                                                  lock_at: 1.month.from_now)
+      overridden = AssignmentOverrideApplicator.assignment_with_overrides(@assignment, [past_override, future_override])
+      expect(overridden.locked_for?(@student)).to be_truthy
+    end
+
+    it "should not be locked when in an override" do
+      override = assignment_override_model(assignment: @assignment,
+                                           unlock_at: 2.months.ago,
+                                           lock_at: 2.months.from_now)
+      overridden = AssignmentOverrideApplicator.assignment_with_overrides(@assignment, [override])
+      expect(overridden.locked_for?(@student)).to be(false)
+    end
   end
 
   describe "collapsed_overrides" do
@@ -1021,6 +1040,13 @@ def fancy_midnight(opts={})
       unlock_at = AssignmentOverrideApplicator.overridden_unlock_at(@assignment, [@override])
       expect(unlock_at).to eq @override.unlock_at
     end
+
+    it "should not include unlock_at for previous overrides that have already been locked" do
+      @override.override_unlock_at(10.days.ago)
+      @override.override_lock_at(5.days.ago)
+      unlock_at = AssignmentOverrideApplicator.overridden_unlock_at(@assignment, [@override])
+      expect(unlock_at).to eq @assignment.unlock_at
+    end
   end
 
   describe "overridden_lock_at" do

spec/models/assignment_override_spec.rb

@@ -28,7 +28,7 @@
     @override_student = @override.assignment_override_students.build
     @override_student.user = @student
     @override_student.save!
-    
+
     @override.destroy
     expect(AssignmentOverride.where(id: @override).first).not_to be_nil
     expect(@override.workflow_state).to eq 'deleted'
@@ -472,6 +472,49 @@ def fancy_midnight(opts={})
 
   end
 
+  describe '#availability_expired?' do
+    let(:override) { assignment_override_model }
+    subject { override.availability_expired? }
+
+    context 'without an overridden lock_at' do
+      before do
+        override.lock_at_overridden = false
+      end
+
+      it { is_expected.to be(false) }
+    end
+
+    context 'with an overridden lock_at' do
+      before do
+        override.lock_at_overridden = true
+      end
+
+      context 'never locks' do
+        before do
+          override.lock_at = nil
+        end
+
+        it { is_expected.to be(false) }
+      end
+
+      context 'not yet locked' do
+        before do
+          override.lock_at = 10.minutes.from_now
+        end
+
+        it { is_expected.to be(false) }
+      end
+
+      context 'already locked' do
+        before do
+          override.lock_at = 10.minutes.ago
+        end
+
+        it { is_expected.to be(true) }
+      end
+    end
+  end
+
   describe "default_values" do
     let(:override) { AssignmentOverride.new }
     let(:quiz) { Quizzes::Quiz.new }