Fix scheduling epic migration

db/post_migrate/20190926180443_schedule_epic_issues_after_epics_move.rb

@@ -25,7 +25,7 @@ class ScheduleEpicIssuesAfterEpicsMove < ActiveRecord::Migration[5.2]
     Epic.each_batch(of: BATCH_SIZE) do |batch, index|
       range = batch.pluck('MIN(id)', 'MAX(id)').first
       delay = index * INTERVAL
-      BackgroundMigrationWorker.perform_in(delay, MIGRATION, *range)
+      BackgroundMigrationWorker.perform_in(delay, MIGRATION, range)
     end
   end
 

ee/spec/migrations/20190926180443_schedule_epic_issues_after_epics_move_spec.rb

+# frozen_string_literal: true
+
+require 'spec_helper'
+require Rails.root.join('db', 'post_migrate', '20190926180443_schedule_epic_issues_after_epics_move.rb')
+
+RSpec.describe ScheduleEpicIssuesAfterEpicsMove do
+  let(:users) { table(:users) }
+  let(:namespaces) { table(:namespaces) }
+  let(:projects) { table(:projects) }
+  let(:epics) { table(:epics) }
+  let(:issues) { table(:issues) }
+  let(:epic_issues) { table(:epic_issues) }
+
+  let(:user) { users.create!(name: 'test', email: 'test@example.com', projects_limit: 5) }
+  let(:group) { namespaces.create!(name: 'gitlab', path: 'gitlab-org') }
+  let(:project) { projects.create!(namespace_id: group.id, name: 'foo') }
+  let(:epic_params) do
+    {
+      title: 'Epic',
+      title_html: 'Epic',
+      group_id: group.id,
+      author_id: user.id
+    }
+  end
+
+  let(:issue_params) do
+    {
+      title: 'Issue',
+      title_html: 'Issue',
+      project_id: project.id,
+      author_id: user.id
+    }
+  end
+
+  let!(:epic_1) { epics.create!(epic_params.merge(iid: 1, relative_position: 100)) }
+  let!(:epic_2) { epics.create!(epic_params.merge(iid: 2, relative_position: 200)) }
+  let!(:epic_3) { epics.create!(epic_params.merge(iid: 3, relative_position: 300)) }
+  let(:issue)   { issues.create!(issue_params.merge(iid: 1)) }
+  let!(:epic_issue) { epic_issues.create!(issue_id: issue.id, epic_id: epic_1.id, relative_position: 1) }
+
+  before do
+    stub_const("#{described_class}::BATCH_SIZE", 2)
+  end
+
+  it 'schedules background migrations at correct time', :aggregate_failures do
+    Sidekiq::Testing.fake! do
+      Timecop.freeze do
+        migrate!
+
+        expect(described_class::MIGRATION).to(
+          be_scheduled_delayed_migration(5.minutes, epic_1.id, epic_2.id)
+        )
+        expect(described_class::MIGRATION).to(
+          be_scheduled_delayed_migration(10.minutes, epic_3.id, epic_3.id)
+        )
+        expect(BackgroundMigrationWorker.jobs.size).to eq(2)
+      end
+    end
+  end
+
+  it 'processes scheduled background migrations', :sidekiq_inline do
+    perform_enqueued_jobs do
+      expect(epic_issue.relative_position).to eq(1)
+
+      migrate!
+
+      expect(epic_issue.reload.relative_position).to be > 300
+    end
+  end
+end