fix: yard docs & add missing

Author: gildesmarais

spec/helper_spec.rb

@@ -25,5 +25,32 @@
     it 'returns the full host' do
       expect(described_class.url_to_host_name('https://news.bbc.co.uk/world')).to eq('news.bbc.co.uk')
     end
+
+    it 'returns nil for blank or invalid URLs', :aggregate_failures do
+      expect(described_class.url_to_host_name(nil)).to be_nil
+      expect(described_class.url_to_host_name('')).to be_nil
+      expect(described_class.url_to_host_name('not a url')).to be_nil
+    end
+  end
+
+  describe 'legacy naming guardrail' do
+    it 'does not expose url_to_directory_name' do
+      expect(described_class).not_to respond_to(:url_to_directory_name)
+    end
+  end
+
+  describe '.registrable_domain' do
+    it 'falls back to host when PublicSuffix returns nil' do
+      allow(PublicSuffix).to receive(:domain).with('example.local').and_return(nil)
+
+      expect(described_class.send(:registrable_domain, 'example.local')).to eq('example.local')
+    end
+
+    it 'falls back to host when PublicSuffix raises DomainInvalid' do
+      allow(PublicSuffix).to receive(:domain).with('invalid..host')
+                                             .and_raise(PublicSuffix::DomainInvalid)
+
+      expect(described_class.send(:registrable_domain, 'invalid..host')).to eq('invalid..host')
+    end
   end
 end

spec/support/helper.rb

@@ -10,7 +10,7 @@
 module Helper
   ##
   # @param url [String]
-  # @return [String]
+  # @return [String, nil]
   def self.url_to_registrable_domain(url)
     host = url_to_host_name(url)
     return host unless host