Delete legacy operations feature flags

We dropped the suppport for the legacy flags in 14.0.
This commits adds a migration to deletes these unused records.

Changelog: other

db/migrate/20210610153556_delete_legacy_operations_feature_flags.rb

+# frozen_string_literal: true
+
+class DeleteLegacyOperationsFeatureFlags < ActiveRecord::Migration[6.1]
+  LEGACY_FEATURE_FLAG_VERSION = 1
+
+  def up
+    execute("DELETE FROM operations_feature_flags WHERE version = #{LEGACY_FEATURE_FLAG_VERSION}")
+  end
+
+  def down
+    # no-op
+  end
+end

db/schema_migrations/20210610153556

+39ca841ce1de3faadee41fbb756d80c98efd853fbbffa7cb3f8f9de56752078b
\ No newline at end of file

spec/migrations/20210610153556_delete_legacy_operations_feature_flags_spec.rb

+# frozen_string_literal: true
+
+require 'spec_helper'
+
+require_migration!('delete_legacy_operations_feature_flags')
+
+RSpec.describe DeleteLegacyOperationsFeatureFlags do
+  let(:namespace) { table(:namespaces).create!(name: 'foo', path: 'bar') }
+  let(:project) { table(:projects).create!(namespace_id: namespace.id) }
+  let(:issue) { table(:issues).create!(id: 123, project_id: project.id) }
+  let(:operations_feature_flags) { table(:operations_feature_flags) }
+  let(:operations_feature_flag_scopes) { table(:operations_feature_flag_scopes) }
+  let(:operations_strategies) { table(:operations_strategies) }
+  let(:operations_scopes) { table(:operations_scopes) }
+  let(:operations_feature_flags_issues) { table(:operations_feature_flags_issues) }
+
+  it 'correctly deletes legacy feature flags' do
+    # Legacy version of a feature flag - dropped support in GitLab 14.0.
+    legacy_flag = operations_feature_flags.create!(project_id: project.id, version: 1, name: 'flag_a', active: true, iid: 1)
+    operations_feature_flag_scopes.create!(feature_flag_id: legacy_flag.id, active: true)
+    operations_feature_flags_issues.create!(feature_flag_id: legacy_flag.id, issue_id: issue.id)
+    # New version of a feature flag.
+    new_flag = operations_feature_flags.create!(project_id: project.id, version: 2, name: 'flag_b', active: true, iid: 2)
+    new_strategy = operations_strategies.create!(feature_flag_id: new_flag.id, name: 'default')
+    operations_scopes.create!(strategy_id: new_strategy.id, environment_scope: '*')
+    operations_feature_flags_issues.create!(feature_flag_id: new_flag.id, issue_id: issue.id)
+
+    expect(operations_feature_flags.all.pluck(:version)).to contain_exactly(1, 2)
+    expect(operations_feature_flag_scopes.count).to eq(1)
+    expect(operations_strategies.count).to eq(1)
+    expect(operations_scopes.count).to eq(1)
+    expect(operations_feature_flags_issues.all.pluck(:feature_flag_id)).to contain_exactly(legacy_flag.id, new_flag.id)
+
+    migrate!
+
+    # Legacy flag is deleted.
+    expect(operations_feature_flags.all.pluck(:version)).to contain_exactly(2)
+    # The associated entries of the legacy flag are deleted too.
+    expect(operations_feature_flag_scopes.count).to eq(0)
+    # The associated entries of the new flag stay instact.
+    expect(operations_strategies.count).to eq(1)
+    expect(operations_scopes.count).to eq(1)
+    expect(operations_feature_flags_issues.all.pluck(:feature_flag_id)).to contain_exactly(new_flag.id)
+  end
+end