FEATURE: Validate domain settings for blocked_onebox_domain only (#15754)

We want to prevent the user from adding ? or * minimally
when setting domains in sitesettings

spec/components/validators/host_list_setting_validator_spec.rb

@@ -0,0 +1,31 @@
+# frozen_string_literal: true
+
+require 'rails_helper'
+
+describe HostListSettingValidator do
+  subject(:validator) { described_class.new() }
+
+  describe '#valid_value?' do
+    describe "returns false for values containing *" do
+      it { expect(validator.valid_value?("*")).to eq false }
+      it { expect(validator.valid_value?("**")).to eq false }
+      it { expect(validator.valid_value?(".*")).to eq false }
+      it { expect(validator.valid_value?("a")).to eq true }
+    end
+
+    describe "returns false for values containing ?" do
+      it { expect(validator.valid_value?("?")).to eq false }
+      it { expect(validator.valid_value?("??")).to eq false }
+      it { expect(validator.valid_value?(".?")).to eq false }
+      it { expect(validator.valid_value?("a")).to eq true }
+    end
+  end
+
+  describe "#error_message" do
+    it "returns invalid domain hostname error" do
+      expect(validator.error_message).to eq(I18n.t(
+        'site_settings.errors.invalid_domain_hostname'
+      ))
+    end
+  end
+end