Fix os.kill tests to be more robust and work with slower machines.

Rather than depending on some sleep value, start up an interpreter
as a subprocess and communicate with it. Because subprocess pipes
can't be read from until EOF and I want to read from them before that,
use ctypes to peek by using PeekNamedPipe. Once the subprocess has
written the message, then it is ready to roll and accept signals.
After that, kill it.

diff --git a/Lib/test/test_os.py b/Lib/test/test_os.py
index d13a2eba68e9adc89f9dcd27328342d3cb2d59fc..e19825214d63b56fefb7cb8fbba5b1e6aaa1932a 100644 (file)
--- a/Lib/test/test_os.py
+++ b/Lib/test/test_os.py
@@ -675,21 +675,59 @@ else:
 
 @unittest.skipUnless(sys.platform == "win32", "Win32 specific tests")
 class Win32KillTests(unittest.TestCase):
-    def _kill(self, sig, *args):
-        # Send a subprocess a signal (or in some cases, just an int to be
-        # the return value)
-        proc = subprocess.Popen(*args)
+    def _kill(self, sig):
+        # Start sys.executable as a subprocess and communicate from the
+        # subprocess to the parent that the interpreter is ready. When it
+        # becomes ready, send *sig* via os.kill to the subprocess and check
+        # that the return code is equal to *sig*.
+        import ctypes
+        from ctypes import wintypes
+        import msvcrt
+
+        # Since we can't access the contents of the process' stdout until the
+        # process has exited, use PeekNamedPipe to see what's inside stdout
+        # without waiting. This is done so we can tell that the interpreter
+        # is started and running at a point where it could handle a signal.
+        PeekNamedPipe = ctypes.windll.kernel32.PeekNamedPipe
+        PeekNamedPipe.restype = wintypes.BOOL
+        PeekNamedPipe.argtypes = (wintypes.HANDLE, # Pipe handle
+                                  ctypes.POINTER(ctypes.c_char), # stdout buf
+                                  wintypes.DWORD, # Buffer size
+                                  ctypes.POINTER(wintypes.DWORD), # bytes read
+                                  ctypes.POINTER(wintypes.DWORD), # bytes avail
+                                  ctypes.POINTER(wintypes.DWORD)) # bytes left
+        msg = "running"
+        proc = subprocess.Popen([sys.executable, "-c",
+                                 "import sys;"
+                                 "sys.stdout.write('{}');"
+                                 "sys.stdout.flush();"
+                                 "input()".format(msg)],
+                                stdout=subprocess.PIPE,
+                                stderr=subprocess.PIPE,
+                                stdin=subprocess.PIPE)
+
+        # Let the process start up (See #3137)
         time.sleep(0.5)
+
+        # Create a string buffer to store the result of stdout from the pipe
+        buf = ctypes.create_string_buffer(len(msg))
+        # Obtain the text currently in proc.stdout
+        # Bytes read/avail/left are left as NULL and unused
+        rslt = PeekNamedPipe(msvcrt.get_osfhandle(proc.stdout.fileno()), buf,
+                             ctypes.sizeof(buf), None, None, None)
+        self.assertNotEqual(rslt, 0, "PeekNamedPipe failed")
+        self.assertEqual(msg, buf.value)
+
         os.kill(proc.pid, sig)
         self.assertEqual(proc.wait(), sig)
 
     def test_kill_sigterm(self):
         # SIGTERM doesn't mean anything special, but make sure it works
-        self._kill(signal.SIGTERM, [sys.executable])
+        self._kill(signal.SIGTERM)
 
     def test_kill_int(self):
         # os.kill on Windows can take an int which gets set as the exit code
-        self._kill(100, [sys.executable])
+        self._kill(100)
 
     def _kill_with_event(self, event, name):
         # Run a script which has console control handling enabled.