add possible and example values

app/models/types_de_champ/prefill_departement_type_de_champ.rb

@@ -0,0 +1,15 @@
+class TypesDeChamp::PrefillDepartementTypeDeChamp < TypesDeChamp::PrefillTypeDeChamp
+  def possible_values
+    departements.map { |departement| "#{departement[:code]} (#{departement[:name]})" }
+  end
+
+  def example_value
+    departements.pick(:code)
+  end
+
+  private
+
+  def departements
+    @departements ||= APIGeoService.departements.sort_by { |departement| departement[:code] }
+  end
+end

app/models/types_de_champ/prefill_type_de_champ.rb

@@ -9,6 +9,8 @@ class TypesDeChamp::PrefillTypeDeChamp < SimpleDelegator
       TypesDeChamp::PrefillPaysTypeDeChamp.new(type_de_champ)
     when TypeDeChamp.type_champs.fetch(:regions)
       TypesDeChamp::PrefillRegionTypeDeChamp.new(type_de_champ)
+    when TypeDeChamp.type_champs.fetch(:departements)
+      TypesDeChamp::PrefillDepartementTypeDeChamp.new(type_de_champ)
     else
       new(type_de_champ)
     end

spec/models/types_de_champ/prefill_departement_type_de_champ_spec.rb

@@ -0,0 +1,26 @@
+# frozen_string_literal: true
+
+RSpec.describe TypesDeChamp::PrefillDepartementTypeDeChamp, type: :model do
+  let(:type_de_champ) { build(:type_de_champ_departements) }
+  let(:memory_store) { ActiveSupport::Cache.lookup_store(:memory_store) }
+
+  before do
+    allow(Rails).to receive(:cache).and_return(memory_store)
+    Rails.cache.clear
+  end
+
+  describe '#possible_values', vcr: { cassette_name: 'api_geo_departements' } do
+    let(:expected_values) {
+      APIGeoService.departements.sort_by { |departement| departement[:code] }.map { |departement| "#{departement[:code]} (#{departement[:name]})" }
+    }
+    subject(:possible_values) { described_class.new(type_de_champ).possible_values }
+
+    it { expect(possible_values).to match(expected_values) }
+  end
+
+  describe '#example_value', vcr: { cassette_name: 'api_geo_departements' } do
+    subject(:example_value) { described_class.new(type_de_champ).example_value }
+
+    it { expect(example_value).to eq(APIGeoService.departements.sort_by { |departement| departement[:code] }.first[:code]) }
+  end
+end

spec/models/types_de_champ/prefill_type_de_champ_spec.rb

@@ -22,6 +22,12 @@ RSpec.describe TypesDeChamp::PrefillTypeDeChamp, type: :model do
       it { expect(built).to be_kind_of(TypesDeChamp::PrefillRegionTypeDeChamp) }
     end
 
+    context 'when the type de champ is a departements' do
+      let(:type_de_champ) { build(:type_de_champ_departements) }
+
+      it { expect(built).to be_kind_of(TypesDeChamp::PrefillDepartementTypeDeChamp) }
+    end
+
     context 'when any other type de champ' do
       let(:type_de_champ) { build(:type_de_champ_date) }