Ignore namespaces.plan_id because it's unused

We already removed all the code that was using this column so we
ignore this column in preparation for removal

app/models/namespace.rb

@@ -11,6 +11,9 @@ class Namespace < ApplicationRecord
   include FeatureGate
   include FromUnion
   include Gitlab::Utils::StrongMemoize
+  include IgnorableColumns
+
+  ignore_column :plan_id, remove_with: '13.1', remove_after: '2020-06-22'
 
   # Prevent users from creating unreasonably deep level of nesting.
   # The number 20 was taken based on maximum nesting level of

config/pseudonymizer.yml

@@ -239,7 +239,6 @@ tables:
     - repository_size_limit
     - require_two_factor_authentication
     - two_factor_grace_period
-    - plan_id
     - project_creation_level
   members:
     whitelist:

ee/app/models/ee/namespace.rb

@@ -27,8 +27,6 @@ module EE
 
       attr_writer :root_ancestor
 
-      belongs_to :plan
-
       has_one :namespace_statistics
       has_one :gitlab_subscription, dependent: :destroy # rubocop:disable Cop/ActiveRecordDependent
 
@@ -62,7 +60,6 @@ module EE
       # Opportunistically clear the +file_template_project_id+ if invalid
       before_validation :clear_file_template_project_id
 
-      validate :validate_plan_name
       validate :validate_shared_runner_minutes_support
 
       validates :max_pages_size,
@@ -294,16 +291,6 @@ module EE
     end
 
     # These helper methods are required to not break the Namespace API.
-    def plan=(plan_name)
-      if plan_name.is_a?(String)
-        @plan_name = plan_name # rubocop:disable Gitlab/ModuleWithInstanceVariables
-
-        super(Plan.find_by(name: @plan_name)) # rubocop:disable Gitlab/ModuleWithInstanceVariables
-      else
-        super
-      end
-    end
-
     def memoized_plans=(plans)
       @plans = plans # rubocop: disable Gitlab/ModuleWithInstanceVariables
     end
@@ -396,12 +383,6 @@ module EE
 
     private
 
-    def validate_plan_name
-      if defined?(@plan_name) && @plan_name.present? && PLANS.exclude?(@plan_name) # rubocop:disable Gitlab/ModuleWithInstanceVariables
-        errors.add(:plan, 'is not included in the list')
-      end
-    end
-
     def validate_shared_runner_minutes_support
       return if shared_runner_minutes_supported?
 

ee/app/models/ee/pages_domain.rb

@@ -5,7 +5,7 @@ module EE
     extend ActiveSupport::Concern
 
     prepended do
-      scope :with_logging_info, -> { includes(project: [:route, { namespace: [:plan, :gitlab_subscription] }]) }
+      scope :with_logging_info, -> { includes(project: [:route, { namespace: :gitlab_subscription }]) }
     end
   end
 end

ee/app/models/plan.rb

@@ -13,7 +13,6 @@ class Plan < ApplicationRecord
   DEFAULT_PLANS = [DEFAULT, FREE].freeze
   ALL_HOSTED_PLANS = (PAID_HOSTED_PLANS + [EARLY_ADOPTER]).freeze
 
-  has_many :namespaces
   has_many :hosted_subscriptions, class_name: 'GitlabSubscription', foreign_key: 'hosted_plan_id'
   has_one :limits, class_name: 'PlanLimits'
 

ee/spec/models/ee/namespace_spec.rb

@@ -14,7 +14,6 @@ describe Namespace do
 
   it { is_expected.to have_one(:namespace_statistics) }
   it { is_expected.to have_one(:gitlab_subscription).dependent(:destroy) }
-  it { is_expected.to belong_to(:plan) }
 
   it { is_expected.to delegate_method(:extra_shared_runners_minutes).to(:namespace_statistics) }
   it { is_expected.to delegate_method(:shared_runners_minutes).to(:namespace_statistics) }
@@ -262,33 +261,6 @@ describe Namespace do
   end
 
   describe 'custom validations' do
-    describe '#validate_plan_name' do
-      let(:group) { build(:group) }
-
-      context 'with a valid plan name' do
-        it 'is valid' do
-          group.plan = create(:bronze_plan)
-
-          expect(group).to be_valid
-        end
-      end
-
-      context 'with an invalid plan name' do
-        it 'is invalid when `unknown`' do
-          group.plan = 'unknown'
-
-          expect(group).not_to be_valid
-          expect(group.errors[:plan]).to include('is not included in the list')
-        end
-
-        it 'is valid for blank strings' do
-          group.plan = ' '
-
-          expect(group).to be_valid
-        end
-      end
-    end
-
     describe '#validate_shared_runner_minutes_support' do
       context 'when changing :shared_runners_minutes_limit' do
         before do

ee/spec/models/plan_spec.rb

@@ -3,10 +3,6 @@
 require 'spec_helper'
 
 describe Plan do
-  describe 'associations' do
-    it { is_expected.to have_many(:namespaces) }
-  end
-
   describe '#default?' do
     subject { plan.default? }
 

ee/spec/support/shared_examples/features/gold_trial_callout_shared_examples.rb

@@ -49,7 +49,6 @@ RSpec.shared_examples 'dashboard gold trial callout' do
 
     it 'hides promotion callout if a gold plan is active', :js do
       group = create(:group_with_plan, name: 'gold group', plan: :gold_plan)
-      group.update(plan: group.gitlab_subscription.hosted_plan)
       group.add_owner(user)
 
       visit page_path