stop deleting submissions upon deactivation

closes EVAL-1298
flag=visible_assignments_scope_change

Test Plan:
1. Enable the visible_assignments_scope_change site admin flag.
2. Create an assignment assigned to a section.
3. As a teacher, deactivate the enrollment of a student in that
   section.
4. Verify the submission for the deactivated student is NOT
   soft-deleted:

   Submission.find_by(assignment_id: <id>, user_id: <id>)
   	.workflow_state # should not be 'deleted'

5. As the student, verify you are not permitted to view the assignment
   page in the UI.
6. As the student, verify the assignments_api_controller#index API
   endpoint does not return the assignment.
7. Re-activate the students deactivated enrollment.
8. As the student, verify you are now permitted to view the assignment
   page in the UI.
9. As the student, verify the assignments_api_controller#index API
   endpoint now returns the assignment.

Change-Id: I300de4bd0999edf55fca5384bb1c56f73e1bec93
Reviewed-on: https://gerrit.instructure.com/c/canvas-lms/+/272227
Tested-by: Service Cloud Jenkins <svc.cloudjenkins@instructure.com>
Reviewed-by: Adrian Packel <apackel@instructure.com>
Reviewed-by: Kai Bjorkman <kbjorkman@instructure.com>
QA-Review: Spencer Olson <solson@instructure.com>
Product-Review: Spencer Olson <solson@instructure.com>

app/models/assignment.rb

@@ -2852,9 +2852,13 @@ class Assignment < ActiveRecord::Base
   scope :for_course, lambda { |course_id| where(:context_type => 'Course', :context_id => course_id) }
   scope :for_group_category, lambda { |group_category_id| where(:group_category_id => group_category_id) }
 
-  scope :visible_to_students_in_course_with_da, lambda { |user_id, _|
-    joins(:submissions)
-      .where(submissions: { :user_id => user_id })
+  scope :visible_to_students_in_course_with_da, lambda { |user_id, course_id|
+    if Account.site_admin.feature_enabled?(:visible_assignments_scope_change)
+      joins(:assignment_student_visibilities)
+        .where(assignment_student_visibilities: { user_id: user_id, course_id: course_id })
+    else
+      joins(:submissions).where(submissions: { user_id: user_id })
+    end
   }
 
   # course_ids should be courses that restrict visibility based on overrides

config/feature_flags/apogee_release_flags.yml

@@ -108,3 +108,8 @@ gradebook_assignment_search_and_redesign:
   display_name: Gradebook Assignment Search And Redesign
   description: Search assignments in Gradebook and new design for assignment
     and student search
+visible_assignments_scope_change:
+  state: hidden
+  applies_to: SiteAdmin
+  display_name: Visible Assignments Scope Change
+  description: Reverts the visible assignments scope to its original form

lib/effective_due_dates.rb

@@ -150,6 +150,14 @@ class EffectiveDueDates
     end
   end
 
+  def filter_section_assigned_enrollments_sql
+    if Account.site_admin.feature_enabled?(:visible_assignments_scope_change)
+      "('rejected', 'deleted')"
+    else
+      "('rejected', 'deleted', 'inactive')"
+    end
+  end
+
   # This beauty of a method brings together assignment overrides,
   # due dates, grading periods, course/group enrollments, etc
   # to calculate each student's effective due date and whether or
@@ -273,7 +281,7 @@ class EffectiveDueDates
             WHERE
               o.set_type = 'CourseSection' AND
               s.workflow_state <> 'deleted' AND
-              e.workflow_state NOT IN ('rejected', 'deleted', 'inactive') AND
+              e.workflow_state NOT IN #{filter_section_assigned_enrollments_sql} AND
               e.type IN ('StudentEnrollment', 'StudentViewEnrollment')
               #{filter_students_sql('e')}
           ),

spec/apis/v1/assignments_api_spec.rb

@@ -923,7 +923,7 @@ describe AssignmentsApiController, type: :request do
           expect(json).to eq []
         end
 
-        it "does not show assignments assigned to  the user has an inactive sectionenrollments for" do
+        it "does not show assignments assigned to the user's inactive section enrollment" do
           inactive_enrollment = @course.enroll_student(@student2, :allow_multiple_enrollments => true,
                                                                   :enrollment_state => 'inactive', :section => @section2)
 

spec/lib/effective_due_dates_spec.rb

@@ -21,6 +21,7 @@ require File.expand_path(File.dirname(__FILE__) + '/../spec_helper.rb')
 
 describe Course do
   before(:once) do
+    Account.site_admin.enable_feature!(:visible_assignments_scope_change)
     @test_course = Course.create!
     course_with_teacher(course: @test_course, active_all: true)
     @teacher = @user
@@ -868,14 +869,28 @@ describe Course do
           expect(edd.to_hash).to eq({})
         end
 
-        it 'unassigns students in the assigned section when they are deactivated' do
+        it 'does not unassign students in the assigned section when they are deactivated' do
           section = CourseSection.create!(name: 'My Awesome Section', course: @test_course)
           student_in_section(section, user: @student1)
-          @assignment1.assignment_overrides.create!(due_at: 1.day.from_now(@now), due_at_overridden: true, set: section)
+          override = @assignment1.assignment_overrides.create!(
+            due_at: 1.day.from_now(@now),
+            due_at_overridden: true,
+            set: section
+          )
           @student1_enrollment.deactivate
 
           edd = EffectiveDueDates.for_course(@test_course, @assignment1)
-          expect(edd.to_hash).to eq({})
+          expect(edd.to_hash).to eq({
+                                      @assignment1.id => {
+                                        @student1.id => {
+                                          due_at: 1.day.from_now(@now),
+                                          grading_period_id: nil,
+                                          in_closed_grading_period: false,
+                                          override_id: override.id,
+                                          override_source: 'CourseSection'
+                                        }
+                                      }
+                                    })
         end
 
         it 'does not unassign students in the assigned section when they are concluded' do

spec/lib/gradebook_exporter_spec.rb

@@ -81,6 +81,7 @@ describe GradebookExporter do
         end
 
         it "returns assignments ordered by assignment group position when feature is disabled" do
+          expect(Account.site_admin).to receive(:feature_enabled?).and_call_original
           expect(Account.site_admin).to receive(:feature_enabled?).with(:gradebook_csv_export_order_matches_gradebook_grid).and_return(false)
 
           actual_assignment_headers = headers[4, 3]
@@ -125,6 +126,7 @@ describe GradebookExporter do
         end
 
         it "returns assignments ordered by assignment group position when feature is disabled" do
+          expect(Account.site_admin).to receive(:feature_enabled?).and_call_original
           expect(Account.site_admin).to receive(:feature_enabled?).with(:gradebook_csv_export_order_matches_gradebook_grid).and_return(false)
 
           actual_assignment_headers = headers[4, 3]

spec/models/assignment_spec.rb

@@ -516,6 +516,66 @@ describe Assignment do
     end
   end
 
+  describe '#visible_to_students_in_course_with_da' do
+    before(:once) do
+      Account.site_admin.enable_feature!(:visible_assignments_scope_change)
+    end
+
+    let(:student_enrollment) { @course.enrollments.find_by(user: @student) }
+    let(:visible_assignments) do
+      Assignment.visible_to_students_in_course_with_da(@student.id, @course.id)
+    end
+
+    it 'excludes unpublished assignments' do
+      assignment = @course.assignments.create!(workflow_state: 'unpublished')
+      expect(visible_assignments).not_to include assignment
+    end
+
+    it 'excludes assignments not assigned to the given user' do
+      section = @course.course_sections.create!
+      assignment = @course.assignments.create!(only_visible_to_overrides: true)
+      create_section_override_for_assignment(assignment, course_section: section)
+      expect(visible_assignments).not_to include assignment
+    end
+
+    it 'excludes assignments assigned to a deactivated enrollment for the given user' do
+      assignment = @course.assignments.create!(only_visible_to_overrides: true)
+      create_section_override_for_assignment(assignment, course_section: student_enrollment.course_section)
+      student_enrollment.deactivate
+      expect(visible_assignments).not_to include assignment
+    end
+
+    it 'excludes assignments that were assigned to the given user and then unassigned' do
+      section = @course.course_sections.create!
+      assignment = @course.assignments.create! # initially assigned
+      assignment.update!(only_visible_to_overrides: true) # unassigned
+      create_section_override_for_assignment(assignment, course_section: section)
+      expect(visible_assignments).not_to include assignment
+    end
+
+    it 'excludes assignments for which the given user submitted something before being unassigned' do
+      section = @course.course_sections.create!
+      assignment = @course.assignments.create!(submission_types: ['online_text_entry']) # initially assigned
+      assignment.submit_homework(@student, submission_type: :online_text_entry, body: :foo)
+      assignment.update!(only_visible_to_overrides: true) # unassigned
+      create_section_override_for_assignment(assignment, course_section: section)
+      expect(visible_assignments).not_to include assignment
+    end
+
+    it 'includes assignments assigned to a concluded enrollment for the given user' do
+      assignment = @course.assignments.create!(only_visible_to_overrides: true)
+      create_section_override_for_assignment(assignment, course_section: student_enrollment.course_section)
+      student_enrollment.conclude
+      expect(visible_assignments).to include assignment
+    end
+
+    it 'includes assignments assigned to an active enrollment for the given user' do
+      assignment = @course.assignments.create!(only_visible_to_overrides: true)
+      create_section_override_for_assignment(assignment, course_section: student_enrollment.course_section)
+      expect(visible_assignments).to include assignment
+    end
+  end
+
   describe '#annotated_document?' do
     before(:once) do
       @assignment = @course.assignments.build