Close #18794: Add a fileno() method and a closed attribute to select.devpoll
objects.

Add also tests on fileno() method and closed attribute of select.epoll and select.kqueue.
diff --git a/Lib/test/test_devpoll.py b/Lib/test/test_devpoll.py
index ec350cd..167e0ee 100644
--- a/Lib/test/test_devpoll.py
+++ b/Lib/test/test_devpoll.py
@@ -87,6 +87,31 @@
         self.assertRaises(OverflowError, pollster.poll, 1 << 63)
         self.assertRaises(OverflowError, pollster.poll, 1 << 64)
 
+    def test_close(self):
+        open_file = open(__file__, "rb")
+        self.addCleanup(open_file.close)
+        fd = open_file.fileno()
+        devpoll = select.devpoll()
+
+        # test fileno() method and closed attribute
+        self.assertIsInstance(devpoll.fileno(), int)
+        self.assertFalse(devpoll.closed)
+
+        # test close()
+        devpoll.close()
+        self.assertTrue(devpoll.closed)
+        self.assertRaises(ValueError, devpoll.fileno)
+
+        # close() can be called more than once
+        devpoll.close()
+
+        # operations must fail with ValueError("I/O operation on closed ...")
+        self.assertRaises(ValueError, devpoll.modify, fd, select.POLLIN)
+        self.assertRaises(ValueError, devpoll.poll)
+        self.assertRaises(ValueError, devpoll.register, fd, fd, select.POLLIN)
+        self.assertRaises(ValueError, devpoll.unregister, fd)
+
+
 def test_main():
     run_unittest(DevPollTests)
 
diff --git a/Lib/test/test_epoll.py b/Lib/test/test_epoll.py
index 7077a70..93a9e1d 100644
--- a/Lib/test/test_epoll.py
+++ b/Lib/test/test_epoll.py
@@ -225,6 +225,31 @@
         server.close()
         ep.unregister(fd)
 
+    def test_close(self):
+        open_file = open(__file__, "rb")
+        self.addCleanup(open_file.close)
+        fd = open_file.fileno()
+        epoll = select.epoll()
+
+        # test fileno() method and closed attribute
+        self.assertIsInstance(epoll.fileno(), int)
+        self.assertFalse(epoll.closed)
+
+        # test close()
+        epoll.close()
+        self.assertTrue(epoll.closed)
+        self.assertRaises(ValueError, epoll.fileno)
+
+        # close() can be called more than once
+        epoll.close()
+
+        # operations must fail with ValueError("I/O operation on closed ...")
+        self.assertRaises(ValueError, epoll.modify, fd, select.EPOLLIN)
+        self.assertRaises(ValueError, epoll.poll, 1.0)
+        self.assertRaises(ValueError, epoll.register, fd, select.EPOLLIN)
+        self.assertRaises(ValueError, epoll.unregister, fd)
+
+
 def test_main():
     support.run_unittest(TestEPoll)
 
diff --git a/Lib/test/test_kqueue.py b/Lib/test/test_kqueue.py
index 5b33af2..930f088 100644
--- a/Lib/test/test_kqueue.py
+++ b/Lib/test/test_kqueue.py
@@ -185,6 +185,28 @@
         b.close()
         kq.close()
 
+    def test_close(self):
+        open_file = open(__file__, "rb")
+        self.addCleanup(open_file.close)
+        fd = open_file.fileno()
+        kqueue = select.kqueue()
+
+        # test fileno() method and closed attribute
+        self.assertIsInstance(kqueue.fileno(), int)
+        self.assertFalse(kqueue.closed)
+
+        # test close()
+        kqueue.close()
+        self.assertTrue(kqueue.closed)
+        self.assertRaises(ValueError, kqueue.fileno)
+
+        # close() can be called more than once
+        kqueue.close()
+
+        # operations must fail with ValueError("I/O operation on closed ...")
+        self.assertRaises(ValueError, kqueue.control, None, 4)
+
+
 def test_main():
     support.run_unittest(TestKQueue)