Add create voucher action and system test

spec/system/admin/vouchers_spec.rb

@@ -0,0 +1,68 @@
+# frozen_string_literal: true
+
+require 'system_helper'
+
+describe '
+    As an administrator
+    I want to manage vouchers
+' do
+  include WebHelper
+  include AuthenticationHelper
+
+  let(:enterprise) { create(:supplier_enterprise, name: 'Feedme') }
+  let(:voucher_code) { 'awesomevoucher' }
+
+  it 'lists enterprise vouchers' do
+    # Given an enterprise with vouchers
+    Voucher.create!(enterprise: enterprise, code: voucher_code)
+
+    # When I go to the enterprise voucher tab
+    login_as_admin_and_visit edit_admin_enterprise_path(enterprise)
+    click_link 'Vouchers'
+
+    # Then I see a list of vouchers
+    expect(page).to have_content voucher_code
+    expect(page).to have_content "10"
+  end
+
+  it 'creates a voucher' do
+    # Given an enterprise
+    # When I go to the new voucher page
+    login_as_admin_and_visit new_admin_enterprise_voucher_path(enterprise)
+
+    # And I fill in the fields for a new voucher click save
+    fill_in 'voucher_code', with: voucher_code
+    click_button 'Save'
+
+    # Then I should get redirect to the entreprise voucher tab and see the created voucher
+    expect(page).to have_selector '.success', text: 'Voucher has been successfully created!'
+
+    # TODO: doesn't automatically show the voucher tab
+    click_link 'Vouchers'
+
+    expect(page).to have_content voucher_code
+    expect(page).to have_content "10"
+
+    voucher = Voucher.where(enterprise: enterprise, code: voucher_code).first
+
+    expect(voucher).not_to be(nil)
+  end
+
+  context 'when entering invalid data' do
+    it 'shows an error flash message' do
+      # Given an enterprise
+      # When I go to the new voucher page
+      login_as_admin_and_visit new_admin_enterprise_voucher_path(enterprise)
+
+      # And I fill in filers with invalid data click save
+      click_button 'Save'
+
+      # Then I should see an error flash message
+      expect(page).to have_selector '.error', text: "Code can't be blank"
+
+      vouchers = Voucher.where(enterprise: enterprise)
+
+      expect(vouchers).to be_empty
+    end
+  end
+end