fixed a child interference problem.

lib/child.js

@@ -1,3 +1,10 @@
+
+//this module SHOULD NOT be required as a library, it will interfere.
+//must be used in a spawned process.
+if (module !== require.main) {
+  return
+}
+
 var testing = require('./testing');
 
 var opts =
@@ -22,6 +29,7 @@ var s = require(process.ARGV[2]);
 
 testing.runSuite(s, opts);
 
+
 function postMessage() {
   console.log(testing.messageEncode.apply(null, arguments));
 }

test/test-interference.js

@@ -0,0 +1,13 @@
+if (module == require.main) {
+  return require('async_testing').run(process.ARGV);
+}
+
+require('../lib/child')
+
+exports ['test should fail'] = function (test){
+    test.ok(false)
+}
+
+/*
+this test will be reported to pass, when clearly it should fail.
+*/