build and render secured URL to invite admin

For clarity and a better understanding, use a dedicated controller to
build and render the confirmation URL to share in order to add a new
administrateur.

spec/controllers/manager/confirmation_urls_controller_spec.rb

@@ -0,0 +1,73 @@
+describe Manager::ConfirmationUrlsController, type: :controller do
+  let(:inviter_super_admin) { create(:super_admin) }
+  let(:inviter_administrateur) { create(:administrateur, email: inviter_super_admin.email) }
+
+  let(:invited_super_admin) { create(:super_admin) }
+  let(:invited_administrateur) { create(:administrateur, email: invited_super_admin.email) }
+
+  let(:procedure) { create(:procedure, administrateurs: [inviter_administrateur]) }
+
+  before { sign_in inviter_super_admin }
+
+  describe "#add_administrateur_with_confirmation" do
+    render_views
+
+    let(:params) do
+      {
+        procedure_id: procedure.id,
+        email: invited_administrateur.email
+      }
+    end
+
+    before { get :new, params: params }
+
+    it { expect(response).to render_template(:new) }
+
+    it { expect(response.body).to match(/Veuillez partager ce lien/) }
+
+    it "shows the confirmation url with encrypted parameters" do
+      expect(response.body).to include(
+        confirm_add_administrateur_manager_procedure_url(
+          procedure,
+          q: encrypt({ email: invited_administrateur.email, inviter_id: inviter_super_admin.id })
+        )
+      )
+    end
+
+    describe 'edge cases' do
+      context 'when the administrateur does not exist' do
+        let(:params) do
+          {
+            procedure_id: procedure.id,
+            email: "wrong@email.com"
+          }
+        end
+
+        it { expect(flash[:alert]).to match(/Cet administrateur n'existe pas/) }
+
+        it { expect(response).to redirect_to(manager_procedure_path(procedure)) }
+      end
+
+      context 'when the administrateur has already been added to the procedure' do
+        let(:params) do
+          {
+            procedure_id: procedure.id,
+            email: inviter_super_admin.email
+          }
+        end
+
+        it { expect(flash[:alert]).to match(/Cet administrateur a déjà été ajouté/) }
+
+        it { expect(response).to redirect_to(manager_procedure_path(procedure)) }
+      end
+    end
+  end
+
+  private
+
+  def encrypt(parameters)
+    key = Rails.application.key_generator.generate_key(ENV["SECRET_KEY_BASE"])
+    verifier = ActiveSupport::MessageVerifier.new(key)
+    Base64.urlsafe_encode64(verifier.generate(parameters))
+  end
+end