1 files changed, 98 insertions, 0 deletions
diff --git a/activesupport/lib/active_support/testing/isolation.rb b/activesupport/lib/active_support/testing/isolation.rb
new file mode 100644
index 0000000000..090e0c5c89
--- /dev/null
+++ b/activesupport/lib/active_support/testing/isolation.rb
@@ -0,0 +1,98 @@
+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 self.forking_env?
+      !ENV["NO_FORK"] && RUBY_PLATFORM !~ /mswin|mingw|java/
+    end
+
+    def run(result)
+      yield(Test::Unit::TestCase::STARTED, name)
+
+      @_result = result
+
+      proxy = run_in_isolation do |proxy|
+        super(proxy) { }
+      end
+
+      proxy.__replay__(@_result)
+
+      yield(Test::Unit::TestCase::FINISHED, name)
+    end
+
+    module Forking
+      def run_in_isolation(&blk)
+        read, write = IO.pipe
+
+        pid = fork do
+          read.close
+          proxy = ProxyTestResult.new
+          yield proxy
+          write.puts [Marshal.dump(proxy)].pack("m")
+          exit!
+        end
+
+        write.close
+        result = read.read
+        Process.wait2(pid)
+        Marshal.load(result.unpack("m")[0])
+      end
+    end
+
+    module Subprocess
+      # Crazy H4X to get this working in windows / jruby with
+      # no forking.
+      def run_in_isolation(&blk)
+        require "tempfile"
+
+        if ENV["ISOLATION_TEST"]
+          proxy = ProxyTestResult.new
+          yield proxy
+          File.open(ENV["ISOLATION_OUTPUT"], "w") do |file|
+            file.puts [Marshal.dump(proxy)].pack("m")
+          end
+          exit!
+        else
+          Tempfile.open("isolation") do |tmpfile|
+            ENV["ISOLATION_TEST"]   = @method_name
+            ENV["ISOLATION_OUTPUT"] = tmpfile.path
+
+            load_paths = $-I.map {|p| "-I\"#{File.expand_path(p)}\"" }.join(" ")
+            `#{Gem.ruby} #{load_paths} #{$0} #{ORIG_ARGV.join(" ")} -t\"#{self.class}\"`
+
+            ENV.delete("ISOLATION_TEST")
+            ENV.delete("ISOLATION_OUTPUT")
+
+            return Marshal.load(tmpfile.read.unpack("m")[0])
+          end
+        end
+      end
+    end
+
+    include forking_env? ? Forking : Subprocess
+  end
+end
+
+# Only in subprocess for windows / jruby.
+if ENV['ISOLATION_TEST']
+  require "test/unit/collector/objectspace"
+  class Test::Unit::Collector::ObjectSpace
+    def include?(test)
+      super && test.method_name == ENV['ISOLATION_TEST']
+    end
+  end
+end
+\ No newline at end of file