Explicit test dependencies

activesupport/test/core_ext/array_ext_test.rb

 require 'abstract_unit'
 require 'bigdecimal'
+require 'active_support/core_ext/array'
 
 class ArrayExtAccessTests < Test::Unit::TestCase
   def test_from

activesupport/test/core_ext/class_test.rb

 require 'abstract_unit'
+require 'active_support/core_ext/class'
 
 class A
 end

activesupport/test/core_ext/date_ext_test.rb

 require 'abstract_unit'
+require 'active_support/core_ext/date'
 
 class DateExtCalculationsTest < Test::Unit::TestCase
   def test_to_s

activesupport/test/core_ext/file_test.rb

 require 'abstract_unit'
+require 'active_support/core_ext/file'
 
 class AtomicWriteTest < Test::Unit::TestCase
   def test_atomic_write_without_errors

activesupport/test/core_ext/string_ext_test.rb

@@ -3,8 +3,7 @@
 require 'abstract_unit'
 require 'inflector_test_cases'
 
-require 'active_support/core_ext/string/conversions'
-require 'active_support/core_ext/string/filters'
+require 'active_support/core_ext/string'
 
 class StringInflectionsTest < Test::Unit::TestCase
   include InflectorTestCases