Collect the date a SaaS trial starts on

Adds a trial_starts_on column to gitlab_subscriptions (and the
gitlab_subscription_histories  tables) and sets it to the start_date
whenever a new trial is created or updated.

changelogs/unreleased/36751-collect-the-date-a-saas-trial-starts-on.yml

+---
+title: Collect the date a SaaS trial starts on
+merge_request: 20384
+author:
+type: added

db/migrate/20191127151629_add_trial_starts_on_to_gitlab_subscriptions.rb

+# frozen_string_literal: true
+
+class AddTrialStartsOnToGitlabSubscriptions < ActiveRecord::Migration[5.2]
+  DOWNTIME = false
+
+  def change
+    add_column :gitlab_subscriptions, :trial_starts_on, :date, null: true
+    add_column :gitlab_subscription_histories, :trial_starts_on, :date, null: true
+  end
+end

db/schema.rb

@@ -1849,6 +1849,7 @@ ActiveRecord::Schema.define(version: 2019_12_06_122926) do
     t.integer "change_type", limit: 2
     t.bigint "gitlab_subscription_id", null: false
     t.datetime_with_timezone "created_at"
+    t.date "trial_starts_on"
     t.index ["gitlab_subscription_id"], name: "index_gitlab_subscription_histories_on_gitlab_subscription_id"
   end
 
@@ -1863,6 +1864,7 @@ ActiveRecord::Schema.define(version: 2019_12_06_122926) do
     t.integer "max_seats_used", default: 0
     t.integer "seats", default: 0
     t.boolean "trial", default: false
+    t.date "trial_starts_on"
     t.index ["hosted_plan_id"], name: "index_gitlab_subscriptions_on_hosted_plan_id"
     t.index ["namespace_id"], name: "index_gitlab_subscriptions_on_namespace_id", unique: true
   end

ee/app/models/ee/namespace.rb

@@ -64,7 +64,7 @@ module EE
       validate :validate_plan_name
       validate :validate_shared_runner_minutes_support
 
-      delegate :trial?, :trial_ends_on, :upgradable?, to: :gitlab_subscription, allow_nil: true
+      delegate :trial?, :trial_ends_on, :trial_starts_on, :upgradable?, to: :gitlab_subscription, allow_nil: true
 
       before_create :sync_membership_lock_with_parent
 

ee/lib/ee/api/namespaces.rb

@@ -42,6 +42,7 @@ module EE
               optional :end_date, type: Date, desc: 'The date when subscription expires'
               optional :trial, type: Grape::API::Boolean, desc: 'Wether the subscription is trial'
               optional :trial_ends_on, type: Date, desc: 'The date when the trial expires'
+              optional :trial_starts_on, type: Date, desc: 'The date when the trial starts'
             end
           end
 
@@ -82,6 +83,7 @@ module EE
             namespace = find_namespace!(params[:id])
 
             subscription_params = declared_params(include_missing: false)
+            subscription_params[:trial_starts_on] ||= subscription_params[:start_date] if subscription_params[:trial]
             subscription = namespace.create_gitlab_subscription(subscription_params)
             if subscription.persisted?
               present subscription, with: ::EE::API::Entities::GitlabSubscription
@@ -118,7 +120,10 @@ module EE
             not_found!('GitlabSubscription') unless subscription
             bad_request!("Invalid trial expiration date") if trial_ends_on&.past?
 
-            if subscription.update(declared_params(include_missing: false))
+            subscription_params = declared_params(include_missing: false)
+            subscription_params[:trial_starts_on] ||= subscription_params[:start_date] if subscription_params[:trial]
+
+            if subscription.update(subscription_params)
               present subscription, with: ::EE::API::Entities::GitlabSubscription
             else
               render_validation_error!(subscription)

ee/spec/requests/api/namespaces_spec.rb

@@ -220,6 +220,13 @@ describe API::Namespaces do
         expect(group1.gitlab_subscription).to be_present
       end
 
+      it 'sets the trial_starts_on to the start_date' do
+        do_post(admin, params.merge(trial: true))
+
+        expect(group1.gitlab_subscription.trial_starts_on).to be_present
+        expect(group1.gitlab_subscription.trial_starts_on.strftime('%d/%m/%Y')).to eq(params[:start_date])
+      end
+
       it 'creates a subscription using full_path when the namespace path contains dots' do
         post api("/namespaces/#{group1.full_path}/gitlab_subscription", admin), params: params