2 files changed, 40 insertions, 0 deletions
diff --git a/activesupport/lib/active_support/test_case.rb b/activesupport/lib/active_support/test_case.rb
index bab2a401eb..e99a4854ce 100644
--- a/activesupport/lib/active_support/test_case.rb
+++ b/activesupport/lib/active_support/test_case.rb
@@ -13,6 +13,7 @@ require 'active_support/testing/assertions'
 require 'active_support/testing/deprecation'
 require 'active_support/testing/declarative'
 require 'active_support/testing/pending'
+require 'active_support/testing/isolation'
 
 module ActiveSupport
   class TestCase < ::Test::Unit::TestCase
diff --git a/activesupport/lib/active_support/testing/isolation.rb b/activesupport/lib/active_support/testing/isolation.rb
new file mode 100644
index 0000000000..8b2957fbe1
--- /dev/null
+++ b/activesupport/lib/active_support/testing/isolation.rb
@@ -0,0 +1,39 @@
+module ActiveSupport::Testing
+  class ProxyTestResult
+    def initialize
+      @calls = []
+    end
+
+    def __replay__(result)
+      @calls.each do |name, args|
+        result.send(name, *args)
+      end
+    end
+
+    def method_missing(name, *args)
+      @calls << [name, args]
+    end
+  end
+
+  module Isolation
+    def run(result)
+      yield(Test::Unit::TestCase::STARTED, name)
+
+      read, write = IO.pipe
+
+      pid = fork do
+        # child
+        read.close
+        proxy = ProxyTestResult.new
+        super(proxy) { }
+        write.puts [Marshal.dump(proxy)].pack("m")
+        exit!
+      end
+
+      write.close
+      Marshal.load(read.read.unpack("m")[0]).__replay__(result)
+      Process.wait2(pid)
+      yield(Test::Unit::TestCase::FINISHED, name)
+    end
+  end
+end
+\ No newline at end of file