Add test_signal from CPython 3.8

Adds signalinterproctester as a supporting file

Author: fanninpm

Lib/test/signalinterproctester.py

@@ -0,0 +1,83 @@
+import os
+import signal
+import subprocess
+import sys
+import time
+import unittest
+
+
+class SIGUSR1Exception(Exception):
+    pass
+
+
+class InterProcessSignalTests(unittest.TestCase):
+    def setUp(self):
+        self.got_signals = {'SIGHUP': 0, 'SIGUSR1': 0, 'SIGALRM': 0}
+
+    def sighup_handler(self, signum, frame):
+        self.got_signals['SIGHUP'] += 1
+
+    def sigusr1_handler(self, signum, frame):
+        self.got_signals['SIGUSR1'] += 1
+        raise SIGUSR1Exception
+
+    def wait_signal(self, child, signame):
+        if child is not None:
+            # This wait should be interrupted by exc_class
+            # (if set)
+            child.wait()
+
+        timeout = 10.0
+        deadline = time.monotonic() + timeout
+
+        while time.monotonic() < deadline:
+            if self.got_signals[signame]:
+                return
+            signal.pause()
+
+        self.fail('signal %s not received after %s seconds'
+                  % (signame, timeout))
+
+    def subprocess_send_signal(self, pid, signame):
+        code = 'import os, signal; os.kill(%s, signal.%s)' % (pid, signame)
+        args = [sys.executable, '-I', '-c', code]
+        return subprocess.Popen(args)
+
+    def test_interprocess_signal(self):
+        # Install handlers. This function runs in a sub-process, so we
+        # don't worry about re-setting the default handlers.
+        signal.signal(signal.SIGHUP, self.sighup_handler)
+        signal.signal(signal.SIGUSR1, self.sigusr1_handler)
+        signal.signal(signal.SIGUSR2, signal.SIG_IGN)
+        signal.signal(signal.SIGALRM, signal.default_int_handler)
+
+        # Let the sub-processes know who to send signals to.
+        pid = str(os.getpid())
+
+        with self.subprocess_send_signal(pid, "SIGHUP") as child:
+            self.wait_signal(child, 'SIGHUP')
+        self.assertEqual(self.got_signals, {'SIGHUP': 1, 'SIGUSR1': 0,
+                                            'SIGALRM': 0})
+
+        with self.assertRaises(SIGUSR1Exception):
+            with self.subprocess_send_signal(pid, "SIGUSR1") as child:
+                self.wait_signal(child, 'SIGUSR1')
+        self.assertEqual(self.got_signals, {'SIGHUP': 1, 'SIGUSR1': 1,
+                                            'SIGALRM': 0})
+
+        with self.subprocess_send_signal(pid, "SIGUSR2") as child:
+            # Nothing should happen: SIGUSR2 is ignored
+            child.wait()
+
+        try:
+            with self.assertRaises(KeyboardInterrupt):
+                signal.alarm(1)
+                self.wait_signal(None, 'SIGALRM')
+            self.assertEqual(self.got_signals, {'SIGHUP': 1, 'SIGUSR1': 1,
+                                                'SIGALRM': 0})
+        finally:
+            signal.alarm(0)
+
+
+if __name__ == "__main__":
+    unittest.main()