1 files changed, 15 insertions, 0 deletions
diff --git a/lib/rubygems/resolver/vendor_set.rb b/lib/rubygems/resolver/vendor_set.rb
index c8826005a7..339492f690 100644
--- a/lib/rubygems/resolver/vendor_set.rb
+++ b/lib/rubygems/resolver/vendor_set.rb
@@ -64,5 +64,20 @@ class Gem::Resolver::VendorSet < Gem::Resolver::Set
     @specs.fetch key
   end
 
+  def pretty_print q # :nodoc:
+    q.group 2, '[VendorSet', ']' do
+      next if @directories.empty?
+      q.breakable
+
+      dirs = @directories.map do |spec, directory|
+        "#{spec.full_name}: #{directory}"
+      end
+
+      q.seplist dirs do |dir|
+        q.text dir
+      end
+    end
+  end
+
 end