Migrate legacy moderated graders to new moderation_graders table

fixes GRADE-1020

test plan: migrations run and specs pass

Change-Id: I03ee7f87139b5d5373e7c62942670741f50d9ff1
Reviewed-on: https://gerrit.instructure.com/152299
Reviewed-by: Adrian Packel <apackel@instructure.com>
Reviewed-by: Spencer Olson <solson@instructure.com>
Tested-by: Jenkins
QA-Review: Neil Gupta <ngupta@instructure.com>
Product-Review: Keith T. Garner <kgarner@instructure.com>

db/migrate/20180601143016_backfill_moderation_graders.rb

@@ -0,0 +1,34 @@
+#
+# Copyright (C) 2018 - present Instructure, Inc.
+#
+# This file is part of Canvas.
+#
+# Canvas is free software: you can redistribute it and/or modify it under
+# the terms of the GNU Affero General Public License as published by the Free
+# Software Foundation, version 3 of the License.
+#
+# Canvas is distributed in the hope that it will be useful, but WITHOUT ANY
+# WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS FOR
+# A PARTICULAR PURPOSE. See the GNU Affero General Public License for more
+# details.
+#
+# You should have received a copy of the GNU Affero General Public License along
+# with this program. If not, see <http://www.gnu.org/licenses/>.
+
+class BackfillModerationGraders < ActiveRecord::Migration[5.0]
+  tag :postdeploy
+
+  def self.up
+    Assignment.where(moderated_grading: true).where("grader_count = 0 or grader_count is null").find_ids_in_ranges do |start_at, end_at|
+      DataFixup::BackfillModerationGraders.send_later_if_production_enqueue_args(
+        :run,
+        {
+          priority: Delayed::LOW_PRIORITY,
+          n_strand: ["DataFixup::BackfillModerationGraders", Shard.current.database_server.id]
+        },
+        start_at,
+        end_at
+      )
+    end
+  end
+end

lib/data_fixup/backfill_moderation_graders.rb

@@ -0,0 +1,79 @@
+#
+# Copyright (C) 2018 - present Instructure, Inc.
+#
+# This file is part of Canvas.
+#
+# Canvas is free software: you can redistribute it and/or modify it under
+# the terms of the GNU Affero General Public License as published by the Free
+# Software Foundation, version 3 of the License.
+#
+# Canvas is distributed in the hope that it will be useful, but WITHOUT ANY
+# WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS FOR
+# A PARTICULAR PURPOSE. See the GNU Affero General Public License for more
+# details.
+#
+# You should have received a copy of the GNU Affero General Public License along
+# with this program. If not, see <http://www.gnu.org/licenses/>.
+#
+
+module DataFixup::BackfillModerationGraders
+  def self.run(start_at, end_at)
+    assignments = Assignment.where(id: start_at..end_at).where(moderated_grading: true).where("grader_count = 0 or grader_count is null")
+
+    courses = assignments.distinct.pluck(:context_id)
+    return if courses.blank?
+
+    # Find all provisional graders for this batch of assignments
+    graders = ModeratedGrading::ProvisionalGrade.joins(:submission).
+      where("submissions.assignment_id IN (?)", assignments.select(:id)).
+      pluck("distinct submissions.assignment_id, moderated_grading_provisional_grades.scorer_id")
+    created_at = Time.zone.now
+
+    Assignment.transaction do
+      unless graders.blank?
+        # generate unique anonymous ids for each grader
+        existing_anonymous_ids = Hash.new { |hsh, key| hsh[key] = [] }
+        graders.map! do |assignment_id, grader_id|
+          anonymous_id = Anonymity.generate_id(existing_ids: existing_anonymous_ids[assignment_id])
+          existing_anonymous_ids[assignment_id] << anonymous_id
+          {
+            anonymous_id: anonymous_id,
+            assignment_id: assignment_id,
+            user_id: grader_id,
+            created_at: created_at,
+            updated_at: created_at
+          }
+        end
+        ModerationGrader.bulk_insert(graders)
+
+        existing_anonymous_ids.each do |assignment_id, grader_ids|
+          Assignment.where(id: assignment_id).update_all(grader_count: [grader_ids.length, 2].max, updated_at: created_at)
+        end
+      end
+
+      # update remaining assignments with default 2 grader count
+      assignments.update_all(grader_count: 2, updated_at: created_at)
+
+      # Turn on moderated_grading feature flag for all courses of these assignments
+      courses.map! do |course_id|
+        vals = [
+          Course.connection.quote(course_id),
+          Course.connection.quote('Course'),
+          Course.connection.quote('moderated_grading'),
+          Course.connection.quote('on'),
+          Course.connection.quote(created_at),
+          Course.connection.quote(created_at)
+        ]
+        "(#{vals.join(',')})"
+      end
+      ActiveRecord::Base.connection.exec_insert <<~SQL
+        INSERT INTO #{FeatureFlag.quoted_table_name}
+          (context_id, context_type, feature, state, created_at, updated_at) VALUES #{courses.join(',')}
+          ON CONFLICT (context_id, context_type, feature) DO UPDATE SET
+            state = excluded.state,
+            updated_at = excluded.updated_at
+          WHERE feature_flags.state <> excluded.state
+      SQL
+    end
+  end
+end

spec/lib/data_fixup/backfill_moderation_graders_spec.rb

@@ -0,0 +1,84 @@
+#
+# Copyright (C) 2018 - present Instructure, Inc.
+#
+# This file is part of Canvas.
+#
+# Canvas is free software: you can redistribute it and/or modify it under
+# the terms of the GNU Affero General Public License as published by the Free
+# Software Foundation, version 3 of the License.
+#
+# Canvas is distributed in the hope that it will be useful, but WITHOUT ANY
+# WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS FOR
+# A PARTICULAR PURPOSE. See the GNU Affero General Public License for more
+# details.
+#
+# You should have received a copy of the GNU Affero General Public License along
+# with this program. If not, see <http://www.gnu.org/licenses/>.
+
+require 'spec_helper'
+
+describe DataFixup::BackfillModerationGraders do
+  before(:once) do
+    @root_account = account_model
+    @root_account.enable_feature!(:anonymous_moderated_marking)
+    course_factory(account: @root_account)
+    @student = User.create!
+    @course.enroll_student(@student)
+    @teacher = User.create!
+    @course.enroll_teacher(@teacher)
+    @assignment = @course.assignments.create!(title: 'test')
+    @assignment.update_columns(moderated_grading: true, grader_count: 1)
+    @assignment.grade_student(@student, grade: 90, provisional: true, grader: @teacher)
+
+    ModerationGrader.delete_all
+    @assignment.update_columns(grader_count: 0)
+  end
+
+  def do_backfill
+    DataFixup::BackfillModerationGraders.run(@assignment.id, @assignment.id+1)
+  end
+  private :do_backfill
+
+  context "when an assignment has moderated grading disabled" do
+    before(:once) do
+      @assignment.update_columns(moderated_grading: false)
+    end
+
+    it "does not enable Moderated Grading feature flag" do
+      do_backfill
+      expect(@course).not_to be_feature_enabled(:moderated_grading)
+    end
+
+    it "does not set assignments to be anonymously graded" do
+      do_backfill
+      expect(@assignment.reload.grader_count).to eq 0
+    end
+  end
+
+  context "when an assignment has moderated grading enabled" do
+    it "enables Moderated Grading feature flag for the course" do
+      do_backfill
+      expect(@course).to be_feature_enabled(:moderated_grading)
+    end
+
+    it "creates moderation grader for the assignment" do
+      expect { do_backfill }.to change { @assignment.moderation_graders.count }.by(1)
+    end
+
+    it "updates grader count" do
+      do_backfill
+      expect(@assignment.reload.grader_count).to eq 2
+    end
+
+    it "creates anonymous id for moderation grader" do
+      do_backfill
+      expect(@assignment.moderation_graders.first.user_id).to eq @teacher.id
+      expect(@assignment.moderation_graders.first.anonymous_id).not_to be_nil
+    end
+
+    it "re-running fixup is ok" do
+      do_backfill
+      expect { do_backfill }.not_to raise_exception
+    end
+  end
+end