Add opensource plan to database

We have added a new plan and plan limits which would allow the plans
to differentiate between free/paid plan with open source plan.

Changelog: added

db/post_migrate/20211029102822_add_open_source_plan.rb

+# frozen_string_literal: true
+
+class AddOpenSourcePlan < Gitlab::Database::Migration[1.0]
+  class Plan < ActiveRecord::Base
+    self.inheritance_column = :_type_disabled
+
+    has_one :limits, class_name: 'PlanLimits'
+
+    def actual_limits
+      self.limits || self.build_limits
+    end
+  end
+
+  class PlanLimits < ActiveRecord::Base
+    self.inheritance_column = :_type_disabled
+
+    belongs_to :plan
+  end
+
+  def create_plan_limits(plan_limit_name, plan)
+    plan_limit = Plan.find_or_initialize_by(name: plan_limit_name).actual_limits.dup
+    plan_limit.plan = plan
+    plan_limit.save!
+  end
+
+  def up
+    return unless Gitlab.dev_env_or_com?
+
+    opensource = Plan.create!(name: 'opensource', title: 'Open Source Program')
+
+    create_plan_limits('ultimate', opensource)
+  end
+
+  def down
+    return unless Gitlab.dev_env_or_com?
+
+    Plan.where(name: 'opensource').delete_all
+  end
+end

db/schema_migrations/20211029102822

+e1f9d87287048010e9816fd5b4a9a2d30b64d2ad150226852f6679b950031914
\ No newline at end of file

spec/migrations/add_open_source_plan_spec.rb

+# frozen_string_literal: true
+
+require 'spec_helper'
+
+require_migration!
+
+RSpec.describe AddOpenSourcePlan, :migration do
+  describe '#up' do
+    before do
+      allow(Gitlab).to receive(:dev_env_or_com?).and_return true
+    end
+
+    it 'creates 1 entry within the plans table' do
+      expect { migrate! }.to change { AddOpenSourcePlan::Plan.count }.by 1
+      expect(AddOpenSourcePlan::Plan.last.name).to eql('opensource')
+    end
+
+    it 'creates 1 entry for plan limits' do
+      expect { migrate! }.to change { AddOpenSourcePlan::PlanLimits.count }.by 1
+    end
+
+    context 'when the plan limits for gold and silver exists' do
+      before do
+        table(:plans).create!(id: 1, name: 'ultimate', title: 'Ultimate')
+        table(:plan_limits).create!(id: 1, plan_id: 1, storage_size_limit: 2000)
+      end
+
+      it 'duplicates the gold and silvers plan limits entries' do
+        migrate!
+
+        opensource_limits = AddOpenSourcePlan::Plan.find_by(name: 'opensource').limits
+        expect(opensource_limits.storage_size_limit).to be 2000
+      end
+    end
+
+    context 'when the instance is not SaaS' do
+      before do
+        allow(Gitlab).to receive(:dev_env_or_com?).and_return false
+      end
+
+      it 'does not create plans and plan limits and returns' do
+        expect { migrate! }.not_to change { AddOpenSourcePlan::Plan.count }
+      end
+    end
+  end
+
+  describe '#down' do
+    before do
+      table(:plans).create!(id: 3, name: 'other')
+      table(:plan_limits).create!(plan_id: 3)
+    end
+
+    context 'when the instance is SaaS' do
+      before do
+        allow(Gitlab).to receive(:dev_env_or_com?).and_return true
+      end
+
+      it 'removes the newly added opensource entry' do
+        migrate!
+
+        expect { described_class.new.down }.to change { AddOpenSourcePlan::Plan.count }.by(-1)
+        expect(AddOpenSourcePlan::Plan.find_by(name: 'opensource')).to be_nil
+
+        other_plan = AddOpenSourcePlan::Plan.find_by(name: 'other')
+        expect(other_plan).to be_persisted
+        expect(AddOpenSourcePlan::PlanLimits.count).to eq(1)
+        expect(AddOpenSourcePlan::PlanLimits.first.plan_id).to eq(other_plan.id)
+      end
+    end
+
+    context 'when the instance is not SaaS' do
+      before do
+        allow(Gitlab).to receive(:dev_env_or_com?).and_return false
+        table(:plans).create!(id: 1, name: 'opensource', title: 'Open Source Program')
+        table(:plan_limits).create!(id: 1, plan_id: 1)
+      end
+
+      it 'does not delete plans and plan limits and returns' do
+        migrate!
+
+        expect { described_class.new.down }.not_to change { AddOpenSourcePlan::Plan.count }
+        expect(AddOpenSourcePlan::PlanLimits.count).to eq(2)
+      end
+    end
+  end
+end