From e9534445f8c474a31798790fc8e6c3b9d50b3065 Mon Sep 17 00:00:00 2001
From: Mike Dalessio <mike.dalessio@gmail.com>
Date: Wed, 24 May 2023 16:19:05 -0400
Subject: [PATCH] feat: introduce Rails::HTML::Sanitizer.best_supported_vendor

so that callers don't need to check `html5_support?` to choose the
best parser available.
---
 CHANGELOG.md                |  5 ++++-
 lib/rails/html/sanitizer.rb |  4 ++++
 test/rails_api_test.rb      | 14 ++++++++++++++
 3 files changed, 22 insertions(+), 1 deletion(-)

diff --git a/CHANGELOG.md b/CHANGELOG.md
index 811c8d9..1d2a6ab 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -1,6 +1,6 @@
 ## 1.6.0.rc1 / 2023-05-24
 
-* Sanitizers that use an HTML5 parser are now available on platforms supported by
+* HTML5 standards-compliant sanitizers are now available on platforms supported by
   Nokogiri::HTML5. These are available as:
 
   - `Rails::HTML5::FullSanitizer`
@@ -13,6 +13,9 @@
   Note that for symmetry `Rails::HTML4::Sanitizer` is also added, though its behavior is identical
   to the vendor class methods on `Rails::HTML::Sanitizer`.
 
+  Users may call `Rails::HTML::Sanitizer.best_supported_vendor` to get back the HTML5 vendor if it's
+  supported, else the legacy HTML4 vendor.
+
   *Mike Dalessio*
 
 * Module namespaces have changed, but backwards compatibility is provided by aliases.
diff --git a/lib/rails/html/sanitizer.rb b/lib/rails/html/sanitizer.rb
index a6c81f1..b3712a7 100644
--- a/lib/rails/html/sanitizer.rb
+++ b/lib/rails/html/sanitizer.rb
@@ -9,6 +9,10 @@ def html5_support?
 
           @html5_support = Loofah.respond_to?(:html5_support?) && Loofah.html5_support?
         end
+
+        def best_supported_vendor
+          html5_support? ? Rails::HTML5::Sanitizer : Rails::HTML4::Sanitizer
+        end
       end
 
       def sanitize(html, options = {})
diff --git a/test/rails_api_test.rb b/test/rails_api_test.rb
index 4995fef..9bc1107 100644
--- a/test/rails_api_test.rb
+++ b/test/rails_api_test.rb
@@ -17,6 +17,20 @@ def test_html_scrubber_class_names
     assert(Rails::Html::Sanitizer)
   end
 
+  def test_best_supported_vendor_when_html5_is_not_supported_returns_html4
+    Rails::HTML::Sanitizer.stub(:html5_support?, false) do
+      assert_equal(Rails::HTML4::Sanitizer, Rails::HTML::Sanitizer.best_supported_vendor)
+    end
+  end
+
+  def test_best_supported_vendor_when_html5_is_supported_returns_html5
+    skip("no HTML5 support on this platform") unless Rails::HTML::Sanitizer.html5_support?
+
+    Rails::HTML::Sanitizer.stub(:html5_support?, true) do
+      assert_equal(Rails::HTML5::Sanitizer, Rails::HTML::Sanitizer.best_supported_vendor)
+    end
+  end
+
   def test_html4_sanitizer_alias_full
     assert_equal(Rails::HTML4::FullSanitizer, Rails::HTML::FullSanitizer)
     assert_equal("Rails::HTML4::FullSanitizer", Rails::HTML::FullSanitizer.name)