Reschedules migration for uuid recalculation

- Reschedules migration to recalculate to rectify UUID
- Adds specs

Changelog: other
MR: https://gitlab.com/gitlab-org/gitlab/-/merge_requests/68200

db/post_migrate/20210813195518_schedule_recalculate_uuid_on_vulnerabilities_occurrences3.rb

+# frozen_string_literal: true
+
+class ScheduleRecalculateUuidOnVulnerabilitiesOccurrences3 < ActiveRecord::Migration[6.0]
+  include Gitlab::Database::MigrationHelpers
+
+  MIGRATION = 'RecalculateVulnerabilitiesOccurrencesUuid'
+  DELAY_INTERVAL = 2.minutes.to_i
+  BATCH_SIZE = 2_500
+
+  disable_ddl_transaction!
+
+  def up
+    # Make sure that RemoveDuplicateVulnerabilitiesFindings has finished running
+    # so that we don't run into duplicate UUID issues
+    Gitlab::BackgroundMigration.steal('RemoveDuplicateVulnerabilitiesFindings')
+
+    say "Scheduling #{MIGRATION} jobs"
+    queue_background_migration_jobs_by_range_at_intervals(
+      define_batchable_model('vulnerability_occurrences'),
+      MIGRATION,
+      DELAY_INTERVAL,
+      batch_size: BATCH_SIZE,
+      track_jobs: true
+    )
+  end
+
+  def down
+    # no-op
+  end
+end

db/schema_migrations/20210813195518

+848e0201709b3608e76308e9d610e2a4e48ab665c7d8b52f3d23f0a215df58ff
\ No newline at end of file

spec/migrations/schedule_recalculate_uuid_on_vulnerabilities_occurrences3_spec.rb

+# frozen_string_literal: true
+
+require 'spec_helper'
+require_migration!
+
+RSpec.describe ScheduleRecalculateUuidOnVulnerabilitiesOccurrences3 do
+  let(:namespace) { table(:namespaces).create!(name: 'user', path: 'user') }
+  let(:users) { table(:users) }
+  let(:user) { create_user! }
+  let(:project) { table(:projects).create!(id: 123, namespace_id: namespace.id) }
+  let(:scanners) { table(:vulnerability_scanners) }
+  let(:scanner) { scanners.create!(project_id: project.id, external_id: 'test 1', name: 'test scanner 1') }
+  let(:different_scanner) { scanners.create!(project_id: project.id, external_id: 'test 2', name: 'test scanner 2') }
+  let(:vulnerabilities) { table(:vulnerabilities) }
+  let(:vulnerabilities_findings) { table(:vulnerability_occurrences) }
+  let(:vulnerability_identifiers) { table(:vulnerability_identifiers) }
+  let(:vulnerability_identifier) do
+    vulnerability_identifiers.create!(
+      project_id: project.id,
+      external_type: 'uuid-v5',
+      external_id: 'uuid-v5',
+      fingerprint: '7e394d1b1eb461a7406d7b1e08f057a1cf11287a',
+      name: 'Identifier for UUIDv5')
+  end
+
+  let(:different_vulnerability_identifier) do
+    vulnerability_identifiers.create!(
+      project_id: project.id,
+      external_type: 'uuid-v4',
+      external_id: 'uuid-v4',
+      fingerprint: '772da93d34a1ba010bcb5efa9fb6f8e01bafcc89',
+      name: 'Identifier for UUIDv4')
+  end
+
+  let(:vulnerability_for_uuidv4) do
+    create_vulnerability!(
+      project_id: project.id,
+      author_id: user.id
+    )
+  end
+
+  let(:vulnerability_for_uuidv5) do
+    create_vulnerability!(
+      project_id: project.id,
+      author_id: user.id
+    )
+  end
+
+  let!(:finding1) do
+    create_finding!(
+      vulnerability_id: vulnerability_for_uuidv4.id,
+      project_id: project.id,
+      scanner_id: different_scanner.id,
+      primary_identifier_id: different_vulnerability_identifier.id,
+      location_fingerprint: 'fa18f432f1d56675f4098d318739c3cd5b14eb3e',
+      uuid: 'b3cc2518-5446-4dea-871c-89d5e999c1ac'
+    )
+  end
+
+  let!(:finding2) do
+    create_finding!(
+      vulnerability_id: vulnerability_for_uuidv5.id,
+      project_id: project.id,
+      scanner_id: scanner.id,
+      primary_identifier_id: vulnerability_identifier.id,
+      location_fingerprint: '838574be0210968bf6b9f569df9c2576242cbf0a',
+      uuid: '77211ed6-7dff-5f6b-8c9a-da89ad0a9b60'
+    )
+  end
+
+  before do
+    stub_const("#{described_class}::BATCH_SIZE", 1)
+  end
+
+  around do |example|
+    freeze_time { Sidekiq::Testing.fake! { example.run } }
+  end
+
+  it 'schedules background migrations', :aggregate_failures do
+    migrate!
+
+    expect(BackgroundMigrationWorker.jobs.size).to eq(2)
+    expect(described_class::MIGRATION).to be_scheduled_delayed_migration(2.minutes, finding1.id, finding1.id)
+    expect(described_class::MIGRATION).to be_scheduled_delayed_migration(4.minutes, finding2.id, finding2.id)
+  end
+
+  private
+
+  def create_vulnerability!(project_id:, author_id:, title: 'test', severity: 7, confidence: 7, report_type: 0)
+    vulnerabilities.create!(
+      project_id: project_id,
+      author_id: author_id,
+      title: title,
+      severity: severity,
+      confidence: confidence,
+      report_type: report_type
+    )
+  end
+
+  def create_finding!(
+    vulnerability_id:, project_id:, scanner_id:, primary_identifier_id:, location_fingerprint:, uuid:)
+    vulnerabilities_findings.create!(
+      vulnerability_id: vulnerability_id,
+      project_id: project_id,
+      name: 'test',
+      severity: 7,
+      confidence: 7,
+      report_type: 0,
+      project_fingerprint: '123qweasdzxc',
+      scanner_id: scanner_id,
+      primary_identifier_id: primary_identifier_id,
+      location_fingerprint: location_fingerprint,
+      metadata_version: 'test',
+      raw_metadata: 'test',
+      uuid: uuid
+    )
+  end
+
+  def create_user!(name: "Example User", email: "user@example.com", user_type: nil)
+    users.create!(
+      name: name,
+      email: email,
+      username: name,
+      projects_limit: 0
+    )
+  end
+end