determine default zones according to tchap hs

app/models/zone.rb

@@ -33,4 +33,9 @@ class Zone < ApplicationRecord
       OpenStruct.new(id: zone.id, label: zone.label_at(date))
     end
   end
+
+  def self.default_for(tchap_hs)
+    sanitized_sql = ActiveRecord::Base.sanitize_sql "'#{tchap_hs}' = ANY (tchap_hs)"
+    Zone.where(sanitized_sql)
+  end
 end

spec/factories/zone.rb

@@ -1,6 +1,7 @@
 FactoryBot.define do
   factory :zone do
     sequence(:acronym) { |n| "MA#{n}" }
+    tchap_hs { ['agent.educpop.tchap.gouv.fr'] }
     transient do
       labels { [{ designated_on: '1981-05-08', name: "Ministère de l'Education Populaire" }] }
     end

spec/models/zone_spec.rb

@@ -118,4 +118,18 @@ describe Zone do
       expect(Zone.available_at(start_previous_government + 1.day).map(&:label)).to eq ["Ministère de la Culture", "Ministère des Outre-mer"]
     end
   end
+
+  context 'with zones' do
+    before do
+      create(:zone, acronym: 'MEN', tchap_hs: ['agent.education.tchap.gouv.fr'])
+      create(:zone, acronym: 'ESR', tchap_hs: ['agent.education.tchap.gouv.fr'])
+    end
+
+    describe "#self.default_for" do
+      it 'returns zone related to tchap hs' do
+        expect(Zone.default_for('agent.education.tchap.gouv.fr').map(&:acronym)).to eq ['MEN', 'ESR']
+        expect(Zone.default_for('agent.tchap.gouv.fr').map(&:acronym)).to eq []
+      end
+    end
+  end
 end