Only call MiniTest.autorun if the dependecy is present

activesupport/test/xml_mini/libxml_engine_test.rb

-require 'abstract_unit'
-require 'active_support/xml_mini'
-require 'active_support/core_ext/hash/conversions'
-
 begin
   require 'libxml'
 rescue LoadError
   # Skip libxml tests
 else
+require 'abstract_unit'
+require 'active_support/xml_mini'
+require 'active_support/core_ext/hash/conversions'
 
 class LibxmlEngineTest < ActiveSupport::TestCase
   include ActiveSupport

activesupport/test/xml_mini/libxmlsax_engine_test.rb

-require 'abstract_unit'
-require 'active_support/xml_mini'
-require 'active_support/core_ext/hash/conversions'
-
 begin
   require 'libxml'
 rescue LoadError
   # Skip libxml tests
 else
+require 'abstract_unit'
+require 'active_support/xml_mini'
+require 'active_support/core_ext/hash/conversions'
 
 class LibXMLSAXEngineTest < ActiveSupport::TestCase
   include ActiveSupport

activesupport/test/xml_mini/nokogiri_engine_test.rb

-require 'abstract_unit'
-require 'active_support/xml_mini'
-require 'active_support/core_ext/hash/conversions'
-
 begin
   require 'nokogiri'
 rescue LoadError
   # Skip nokogiri tests
 else
+require 'abstract_unit'
+require 'active_support/xml_mini'
+require 'active_support/core_ext/hash/conversions'
 
 class NokogiriEngineTest < ActiveSupport::TestCase
   include ActiveSupport

activesupport/test/xml_mini/nokogirisax_engine_test.rb

-require 'abstract_unit'
-require 'active_support/xml_mini'
-require 'active_support/core_ext/hash/conversions'
-
 begin
   require 'nokogiri'
 rescue LoadError
   # Skip nokogiri tests
 else
+require 'abstract_unit'
+require 'active_support/xml_mini'
+require 'active_support/core_ext/hash/conversions'
 
 class NokogiriSAXEngineTest < ActiveSupport::TestCase
   include ActiveSupport