Add administrative webhooks (#18510)

* Add administrative webhooks

* Fix error when webhook is deleted before delivery worker runs

spec/fabricators/webhook_fabricator.rb

@@ -0,0 +1,5 @@
+Fabricator(:webhook) do
+  url { Faker::Internet.url }
+  secret { SecureRandom.hex }
+  events { Webhook::EVENTS }
+end

spec/models/webhook_spec.rb

@@ -0,0 +1,32 @@
+require 'rails_helper'
+
+RSpec.describe Webhook, type: :model do
+  let(:webhook) { Fabricate(:webhook) }
+
+  describe '#rotate_secret!' do
+    it 'changes the secret' do
+      previous_value = webhook.secret
+      webhook.rotate_secret!
+      expect(webhook.secret).to_not be_blank
+      expect(webhook.secret).to_not eq previous_value
+    end
+  end
+
+  describe '#enable!' do
+    before do
+      webhook.disable!
+    end
+
+    it 'enables the webhook' do
+      webhook.enable!
+      expect(webhook.enabled?).to be true
+    end
+  end
+
+  describe '#disable!' do
+    it 'disables the webhook' do
+      webhook.disable!
+      expect(webhook.enabled?).to be false
+    end
+  end
+end

spec/validators/url_validator_spec.rb

@@ -19,7 +19,7 @@ RSpec.describe URLValidator, type: :validator do
       let(:compliant) { false }
 
       it 'calls errors.add' do
-        expect(errors).to have_received(:add).with(attribute, I18n.t('applications.invalid_url'))
+        expect(errors).to have_received(:add).with(attribute, :invalid)
       end
     end