FIX: validate presence of 'top menu' setting

config/site_settings.yml

@@ -117,6 +117,7 @@ basic:
     default: "latest|new|unread|top|categories"
     regex: "latest"
     regex_error: "site_settings.errors.must_include_latest"
+    validator: RegexPresenceValidator
     choices:
      - latest
      - new

lib/validators/regex_presence_validator.rb

@@ -0,0 +1,16 @@
+class RegexPresenceValidator
+  include RegexSettingValidation
+
+  def initialize(opts = {})
+    @opts = opts
+    initialize_regex_opts(opts)
+  end
+
+  def valid_value?(val)
+    val.present? && regex_match?(val)
+  end
+
+  def error_message
+    I18n.t(@regex_error)
+  end
+end

spec/components/validators/regex_presence_validator_spec.rb

@@ -0,0 +1,31 @@
+require "rails_helper"
+
+RSpec.describe RegexPresenceValidator do
+  subject { described_class.new(regex: 'latest', regex_error: 'site_settings.errors.must_include_latest') }
+
+  describe "#valid_value?" do
+    describe "when value is present" do
+      it "without regex match" do
+        expect(subject.valid_value?("categories|new")).to eq(false)
+
+        expect(subject.error_message).to eq(I18n.t(
+          "site_settings.errors.must_include_latest"
+        ))
+      end
+
+      it "with regex match" do
+        expect(subject.valid_value?("latest|categories")).to eq(true)
+      end
+    end
+
+    describe "when value is empty" do
+      it "should not be valid" do
+        expect(subject.valid_value?("")).to eq(false)
+
+        expect(subject.error_message).to eq(I18n.t(
+          "site_settings.errors.must_include_latest"
+        ))
+      end
+    end
+  end
+end