Patch #1309579: wait3 and wait4 were added to the posix module by Chad J. Schroeder.

This was a fair amount of rework of the patch.  Refactored test_fork1 so it
could be reused by the new tests for wait3/4.  Also made them into new style
unittests (derive from unittest.TestCase).

Lib/test/test_wait4.py

@@ -0,0 +1,29 @@
+"""This test checks for correct wait4() behavior.
+"""
+
+import os
+from test.fork_wait import ForkWait
+from test.test_support import TestSkipped, run_unittest
+
+try:
+    os.fork
+except AttributeError:
+    raise TestSkipped, "os.fork not defined -- skipping test_wait4"
+
+try:
+    os.wait4
+except AttributeError:
+    raise TestSkipped, "os.wait4 not defined -- skipping test_wait4"
+
+class Wait4Test(ForkWait):
+    def wait_impl(self, cpid):
+        spid, status, rusage = os.wait4(cpid, 0)
+        self.assertEqual(spid, cpid)
+        self.assertEqual(status, 0, "cause = %d, exit = %d" % (status&0xff, status>>8))
+        self.assertTrue(rusage)
+
+def test_main():
+    run_unittest(Wait4Test)
+
+if __name__ == "__main__":
+    test_main()