Use Test::Unit::TestCase instead of MiniTest::Unit::TestCase. Because

tests of fiddle already used customized assertions of ruby core.

  * test/fiddle/helper.rb: Use Test::Unit::TestCase for base class of
    testcase.
  * test/fiddle/test_*.rb: Use assert_raise instead of assert_raises.
    Remove needless includes for Test::Unit::Assertions.

git-svn-id: svn+ssh://ci.ruby-lang.org/ruby/trunk@59321 b2dd03c8-39d4-4d8f-98ff-823fe69b080e

test/fiddle/test_function.rb

@@ -6,8 +6,6 @@ end
 
 module Fiddle
   class TestFunction < Fiddle::TestCase
-    include Test::Unit::Assertions
-
     def setup
       super
       Fiddle.last_error = nil