Index: Lib/unittest.py
===================================================================
--- Lib/unittest.py	(revision 64891)
+++ Lib/unittest.py	(working copy)
@@ -786,7 +786,7 @@
 """
     def __init__(self, module='__main__', defaultTest=None,
                  argv=None, testRunner=TextTestRunner,
-                 testLoader=defaultTestLoader):
+                 testLoader=defaultTestLoader, exit=True):
         if type(module) == type(''):
             self.module = __import__(module)
             for part in module.split('.')[1:]:
@@ -799,6 +799,7 @@
         self.defaultTest = defaultTest
         self.testRunner = testRunner
         self.testLoader = testLoader
+        self.exit = exit
         self.progName = os.path.basename(argv[0])
         self.parseArgs(argv)
         self.runTests()
@@ -846,7 +847,8 @@
             # it is assumed to be a TestRunner instance
             testRunner = self.testRunner
         result = testRunner.run(self.test)
-        sys.exit(not result.wasSuccessful())
+        if exit:
+            sys.exit(not result.wasSuccessful())
 
 main = TestProgram