Use assert_separately to inspect test failure of TestJSONGenerate#test_broken_bignum

http://fbsd.rubyci.org/~chkbuild/ruby-trunk/log/20130617T010202Z.log.html.gz#test%2F-ext-

git-svn-id: svn+ssh://ci.ruby-lang.org/ruby/trunk@41350 b2dd03c8-39d4-4d8f-98ff-823fe69b080e

test/json/test_json_generate.rb

@@ -3,6 +3,7 @@
 
 require 'test/unit'
 require File.join(File.dirname(__FILE__), 'setup_variant')
+require_relative '../ruby/envutil.rb'
 
 class TestJSONGenerate < Test::Unit::TestCase
   include JSON
@@ -215,15 +216,14 @@ EOT
   end
 
   def test_gc
-    require_relative '../ruby/envutil.rb'
-    assert_in_out_err(%w[-rjson --disable-gems], <<-EOS, [], [])
+    assert_separately %w[-rjson --disable-gems], <<-EOS, timeout: 5
       bignum_too_long_to_embed_as_string = 1234567890123456789012345
       expect = bignum_too_long_to_embed_as_string.to_s
       GC.stress = true
 
       10.times do |i|
         tmp = bignum_too_long_to_embed_as_string.to_json
-        raise "'\#{expect}' is expected, but '\#{tmp}'" unless tmp == expect
+        assert_equal expect, tmp
       end
     EOS
   end if GC.respond_to?(:stress=)
@@ -252,27 +252,15 @@ EOT
     assert_equal '5', state2.array_nl
   end
 
-  if defined?(JSON::Ext::Generator)
-    def test_broken_bignum # [ruby-core:38867]
-      pid = fork do
-        Bignum.class_eval do
-          def to_s
-          end
-        end
-        begin
-          JSON::Ext::Generator::State.new.generate(1<<64)
-          exit 1
-        rescue TypeError
-          exit 0
+  def test_broken_bignum # [ruby-core:38867]
+    assert_separately %w[-rjson --disable-gems], <<-EOS, timeout: 5
+      Bignum.class_eval do
+        def to_s
         end
       end
-      _, status = Process.waitpid2(pid)
-      assert status.success?
-    rescue NotImplementedError
-      # forking to avoid modifying core class of a parent process and
-      # introducing race conditions of tests are run in parallel
-    end
-  end
+      assert_raise(TypeError){ JSON::Ext::Generator::State.new.generate(1<<64) }
+    EOS
+  end if defined?(JSON::Ext::Generator)
 
   def test_hash_likeness_set_symbol
     state = JSON.state.new