Enable recaptcha check on sign up

reCAPTCHA check was disabled through a feature flag, although it
is shown to the user.

app/controllers/registrations_controller.rb

@@ -139,7 +139,6 @@ class RegistrationsController < Devise::RegistrationsController
     ensure_correct_params!
 
     return unless Feature.enabled?(:registrations_recaptcha, default_enabled: true) # reCAPTCHA on the UI will still display however
-    return if experiment_enabled?(:signup_flow) # when the experimental signup flow is enabled for the current user, disable the reCAPTCHA check
     return unless show_recaptcha_sign_up?
     return unless Gitlab::Recaptcha.load_configurations!
 

changelogs/unreleased/nicolasdular-use-recaptcha-on-signup.yml

+---
+title: Enable recaptcha check on sign up
+merge_request: 24274
+author:
+type: fixed

spec/features/users/signup_spec.rb

@@ -360,7 +360,7 @@ shared_examples 'Signup' do
       InvisibleCaptcha.timestamp_enabled = true
       stub_application_setting(recaptcha_enabled: true)
       allow_next_instance_of(RegistrationsController) do |instance|
-        allow(instance).to receive(:verify_recaptcha).and_return(false)
+        allow(instance).to receive(:verify_recaptcha).and_return(true)
       end
     end
 
@@ -368,6 +368,13 @@ shared_examples 'Signup' do
       InvisibleCaptcha.timestamp_enabled = false
     end
 
+    context 'when reCAPTCHA detects malicious behaviour' do
+      before do
+        allow_next_instance_of(RegistrationsController) do |instance|
+          allow(instance).to receive(:verify_recaptcha).and_return(false)
+        end
+      end
+
       it 'prevents from signing up' do
         visit new_user_registration_path
 
@@ -385,11 +392,29 @@ shared_examples 'Signup' do
         fill_in 'new_user_password', with: new_user.password
 
         expect { click_button 'Register' }.not_to change { User.count }
+        expect(page).to have_content('There was an error with the reCAPTCHA. Please solve the reCAPTCHA again.')
+      end
+    end
+
+    context 'when invisible captcha detects malicious behaviour' do
+      it 'prevents from signing up' do
+        visit new_user_registration_path
+
+        fill_in 'new_user_username', with: new_user.username
+        fill_in 'new_user_email', with: new_user.email
 
         if Gitlab::Experimentation.enabled?(:signup_flow)
-        expect(page).to have_content('That was a bit too quick! Please resubmit.')
+          fill_in 'new_user_first_name', with: new_user.first_name
+          fill_in 'new_user_last_name', with: new_user.last_name
         else
-        expect(page).to have_content('There was an error with the reCAPTCHA. Please solve the reCAPTCHA again.')
+          fill_in 'new_user_name', with: new_user.name
+          fill_in 'new_user_email_confirmation', with: new_user.email
+        end
+
+        fill_in 'new_user_password', with: new_user.password
+
+        expect { click_button 'Register' }.not_to change { User.count }
+        expect(page).to have_content('That was a bit too quick! Please resubmit.')
       end
     end
   end