Invalidate namespace_user_cap_reached Cache

ee/app/helpers/ee/namespace_user_cap_reached_alert_helper.rb

@@ -24,7 +24,7 @@ module EE
     end
 
     def user_cap_reached?(root_namespace)
-      Rails.cache.fetch("namespace_user_cap_reached:#{root_namespace.id}", expires_in: 2.hours) do
+      Rails.cache.fetch(root_namespace.namespace_user_cap_reached_cache_key, expires_in: 2.hours) do
         root_namespace.user_cap_reached?
       end
     end

ee/app/models/ee/group.rb

@@ -490,6 +490,10 @@ module EE
       user_cap <= root_ancestor.billable_members_count(requested_hosted_plan)
     end
 
+    def namespace_user_cap_reached_cache_key
+      "namespace_user_cap_reached:#{root_ancestor.id}"
+    end
+
     private
 
     override :post_create_hook

ee/app/models/ee/member.rb

@@ -30,6 +30,8 @@ module EE
 
       before_create :set_membership_activation
 
+      after_commit :invalidate_namespace_user_cap_cache
+
       scope :with_csv_entity_associations, -> do
         includes(:user, source: [:route, :parent])
       end
@@ -149,5 +151,11 @@ module EE
 
       self.state = group.user_cap_reached? ? STATE_AWAITING : STATE_ACTIVE
     end
+
+    def invalidate_namespace_user_cap_cache
+      return unless group && ::Feature.enabled?(:saas_user_caps, group.root_ancestor, default_enabled: :yaml)
+
+      Rails.cache.delete(group.namespace_user_cap_reached_cache_key)
+    end
   end
 end

ee/spec/helpers/ee/namespace_user_cap_reached_alert_helper_spec.rb

+# frozen_string_literal: true
+
+require 'spec_helper'
+
+RSpec.describe EE::NamespaceUserCapReachedAlertHelper do
+  describe '#display_namespace_user_cap_reached_alert?' do
+    let_it_be(:group, refind: true) do
+      create(:group, :public,
+             namespace_settings: create(:namespace_settings, new_user_signups_cap: 1))
+    end
+
+    let_it_be(:subgroup) { create(:group, parent: group) }
+    let_it_be(:owner) { create(:user) }
+    let_it_be(:developer) { create(:user) }
+
+    before_all do
+      group.add_owner(owner)
+      group.add_developer(developer)
+    end
+
+    before do
+      allow(helper).to receive(:can?).with(owner, :admin_namespace, group).and_return(true)
+      allow(helper).to receive(:can?).with(developer, :admin_namespace, group).and_return(false)
+    end
+
+    it 'returns true when the user cap is reached for a user who can admin the namespace' do
+      sign_in(owner)
+
+      expect(helper.display_namespace_user_cap_reached_alert?(group)).to be true
+    end
+
+    it 'returns false when the user cap is reached for a user who cannot admin the namespace' do
+      sign_in(developer)
+
+      expect(helper.display_namespace_user_cap_reached_alert?(group)).to be false
+    end
+
+    it 'caches the result' do
+      sign_in(owner)
+
+      expect(Rails.cache).to receive(:fetch).with("namespace_user_cap_reached:#{group.id}", expires_in: 2.hours)
+
+      helper.display_namespace_user_cap_reached_alert?(group)
+    end
+
+    it 'caches the result for a subgroup' do
+      sign_in(owner)
+
+      expect(Rails.cache).to receive(:fetch).with("namespace_user_cap_reached:#{group.id}", expires_in: 2.hours)
+
+      helper.display_namespace_user_cap_reached_alert?(subgroup)
+    end
+
+    def sign_in(user)
+      allow(helper).to receive(:current_user).and_return(user)
+    end
+  end
+end

ee/spec/models/member_spec.rb

@@ -249,4 +249,80 @@ RSpec.describe Member, type: :model do
       end
     end
   end
+
+  describe '#invalidate_namespace_user_cap_cache' do
+    let_it_be(:other_user) { create(:user) }
+
+    context 'when the :saas_user_caps feature flag is enabled for the root group' do
+      before do
+        stub_feature_flags(saas_user_caps: group)
+      end
+
+      it 'invalidates the namespace user cap reached cache when adding a member to a group' do
+        expect(Rails.cache).to receive(:delete).with("namespace_user_cap_reached:#{group.id}")
+
+        group.add_developer(other_user)
+      end
+
+      it 'invalidates the cache when adding a member to a subgroup' do
+        expect(Rails.cache).to receive(:delete).with("namespace_user_cap_reached:#{group.id}")
+
+        sub_group.add_developer(other_user)
+      end
+
+      it 'invalidates the cache when adding a member to a project' do
+        expect(Rails.cache).to receive(:delete).with("namespace_user_cap_reached:#{group.id}")
+
+        project.add_developer(other_user)
+      end
+
+      it 'invalidates the cache when removing a member from a group' do
+        expect(Rails.cache).to receive(:delete).with("namespace_user_cap_reached:#{group.id}")
+
+        member.destroy!
+      end
+
+      it 'invalidates the cache when removing a member from a project' do
+        project_member = project.add_developer(other_user)
+        expect(Rails.cache).to receive(:delete).with("namespace_user_cap_reached:#{group.id}")
+
+        project_member.destroy!
+      end
+
+      it 'invalidates the cache when changing the access level' do
+        guest_member = create(:group_member, :guest, group: group, user: other_user)
+
+        expect(Rails.cache).to receive(:delete).with("namespace_user_cap_reached:#{group.id}")
+
+        guest_member.update!(access_level: GroupMember::DEVELOPER)
+      end
+    end
+
+    context 'when the :saas_user_caps feature flag is globally enabled' do
+      before do
+        stub_feature_flags(saas_user_caps: true)
+      end
+
+      it 'does not try to invalidate the cache for a project with a user namespace' do
+        project_owner = create(:user)
+        personal_project = create(:project, namespace: project_owner.namespace)
+
+        expect(Rails.cache).not_to receive(:delete)
+
+        personal_project.add_developer(other_user)
+      end
+    end
+
+    context 'when the :saas_user_caps feature flag is disabled' do
+      before do
+        stub_feature_flags(saas_user_caps: false)
+      end
+
+      it 'does not invalidate the namespace user cap reached cache' do
+        expect(Rails.cache).not_to receive(:delete)
+
+        group.add_developer(other_user)
+      end
+    end
+  end
 end