Return currently used seats for free or trial subscriptions

We need to show the current number of billable seats for free or trial
hosted subscriptions in order to improve the access to this information
for our customers.

ee/app/models/gitlab_subscription.rb

@@ -90,6 +90,14 @@ class GitlabSubscription < ApplicationRecord
     self.hosted_plan = Plan.find_by(name: code)
   end
 
+  # We need to show seats in use for free or trial subscriptions
+  # in order to make it easy for customers to get this information.
+  def seats_in_use
+    return super if has_a_paid_hosted_plan? || !hosted?
+
+    calculate_seats_in_use
+  end
+
   private
 
   def log_previous_state_for_update

ee/changelogs/unreleased/260378-free-gitlab-com-namespaces-should-display-seats-currently-in-us.yml

+---
+title: Return seats in use for free or trial subscriptions
+merge_request: 44973
+author:
+type: changed

ee/spec/features/billings/billing_plans_spec.rb

@@ -107,6 +107,18 @@ RSpec.describe 'Billing plan pages', :feature do
     end
   end
 
+  shared_examples 'currently used seats' do
+    before do
+      visit page_path
+    end
+
+    it 'displays the number of seats', :js do
+      page.within('.js-subscription-table') do
+        expect(page).to have_selector('p.property-value.gl-mt-2.gl-mb-0.number', text: '1')
+      end
+    end
+  end
+
   context 'users profile billing page' do
     let(:page_path) { profile_billings_path }
 
@@ -343,6 +355,13 @@ RSpec.describe 'Billing plan pages', :feature do
 
         it_behaves_like 'can contact sales'
       end
+
+      context 'on free' do
+        let(:plan) { free_plan }
+        let!(:subscription) { create(:gitlab_subscription, namespace: namespace, hosted_plan: plan) }
+
+        it_behaves_like 'currently used seats'
+      end
     end
   end
 
@@ -388,6 +407,7 @@ RSpec.describe 'Billing plan pages', :feature do
 
         it_behaves_like 'downgradable plan'
         it_behaves_like 'non-upgradable plan'
+        it_behaves_like 'currently used seats'
       end
     end
   end

ee/spec/models/gitlab_subscription_spec.rb

@@ -200,6 +200,53 @@ RSpec.describe GitlabSubscription do
     end
   end
 
+  describe '#seats_in_use' do
+    let(:group) { create(:group) }
+    let!(:group_member) { create(:group_member, :developer, user: create(:user), group: group) }
+    let(:hosted_plan) { nil }
+    let(:trial) { false }
+
+    let(:gitlab_subscription) do
+      create(:gitlab_subscription, namespace: group, trial: trial, hosted_plan: hosted_plan, seats_in_use: 5)
+    end
+
+    subject { gitlab_subscription.seats_in_use }
+
+    context 'with a paid plan' do
+      let(:hosted_plan) { gold_plan }
+
+      it 'returns the previously calculated seats in use' do
+        expect(subject).to eq(5)
+      end
+    end
+
+    context 'with a trial plan' do
+      let(:hosted_plan) { gold_plan }
+      let(:trial) { true }
+
+      it 'returns the currently seats in use' do
+        expect(subject).to eq(1)
+      end
+    end
+
+    context 'with a free plan' do
+      let(:hosted_plan) { free_plan }
+
+      it 'returns the currently seats in use' do
+        expect(subject).to eq(1)
+      end
+    end
+
+    context 'with a self hosted plan' do
+      let(:group) { nil }
+      let(:group_member) { nil }
+
+      it 'returns the previously calculated seats in use' do
+        expect(subject).to eq(5)
+      end
+    end
+  end
+
   describe '#expired?' do
     let(:gitlab_subscription) { create(:gitlab_subscription, end_date: end_date) }