bpo-32857: Raise error when tkinter after_cancel() is called with None. (GH-5701)

Lib/tkinter/test/test_tkinter/test_misc.py

@@ -48,6 +48,114 @@ class MiscTest(AbstractTkTest, unittest.TestCase):
                 '^must specify a background color$',
                 root.tk_setPalette, highlightColor='blue')
 
+    def test_after(self):
+        root = self.root
+
+        def callback(start=0, step=1):
+            nonlocal count
+            count = start + step
+
+        # Without function, sleeps for ms.
+        self.assertIsNone(root.after(1))
+
+        # Set up with callback with no args.
+        count = 0
+        timer1 = root.after(0, callback)
+        self.assertIn(timer1, root.tk.call('after', 'info'))
+        (script, _) = root.tk.splitlist(root.tk.call('after', 'info', timer1))
+        root.update()  # Process all pending events.
+        self.assertEqual(count, 1)
+        with self.assertRaises(tkinter.TclError):
+            root.tk.call(script)
+
+        # Set up with callback with args.
+        count = 0
+        timer1 = root.after(0, callback, 42, 11)
+        root.update()  # Process all pending events.
+        self.assertEqual(count, 53)
+
+        # Cancel before called.
+        timer1 = root.after(1000, callback)
+        self.assertIn(timer1, root.tk.call('after', 'info'))
+        (script, _) = root.tk.splitlist(root.tk.call('after', 'info', timer1))
+        root.after_cancel(timer1)  # Cancel this event.
+        self.assertEqual(count, 53)
+        with self.assertRaises(tkinter.TclError):
+            root.tk.call(script)
+
+    def test_after_idle(self):
+        root = self.root
+
+        def callback(start=0, step=1):
+            nonlocal count
+            count = start + step
+
+        # Set up with callback with no args.
+        count = 0
+        idle1 = root.after_idle(callback)
+        self.assertIn(idle1, root.tk.call('after', 'info'))
+        (script, _) = root.tk.splitlist(root.tk.call('after', 'info', idle1))
+        root.update_idletasks()  # Process all pending events.
+        self.assertEqual(count, 1)
+        with self.assertRaises(tkinter.TclError):
+            root.tk.call(script)
+
+        # Set up with callback with args.
+        count = 0
+        idle1 = root.after_idle(callback, 42, 11)
+        root.update_idletasks()  # Process all pending events.
+        self.assertEqual(count, 53)
+
+        # Cancel before called.
+        idle1 = root.after_idle(callback)
+        self.assertIn(idle1, root.tk.call('after', 'info'))
+        (script, _) = root.tk.splitlist(root.tk.call('after', 'info', idle1))
+        root.after_cancel(idle1)  # Cancel this event.
+        self.assertEqual(count, 53)
+        with self.assertRaises(tkinter.TclError):
+            root.tk.call(script)
+
+    def test_after_cancel(self):
+        root = self.root
+
+        def callback():
+            nonlocal count
+            count += 1
+
+        timer1 = root.after(5000, callback)
+        idle1 = root.after_idle(callback)
+
+        # No value for id raises a ValueError.
+        with self.assertRaises(ValueError):
+            root.after_cancel(None)
+
+        # Cancel timer event.
+        count = 0
+        (script, _) = root.tk.splitlist(root.tk.call('after', 'info', timer1))
+        root.tk.call(script)
+        self.assertEqual(count, 1)
+        root.after_cancel(timer1)
+        with self.assertRaises(tkinter.TclError):
+            root.tk.call(script)
+        self.assertEqual(count, 1)
+        with self.assertRaises(tkinter.TclError):
+            root.tk.call('after', 'info', timer1)
+
+        # Cancel same event - nothing happens.
+        root.after_cancel(timer1)
+
+        # Cancel idle event.
+        count = 0
+        (script, _) = root.tk.splitlist(root.tk.call('after', 'info', idle1))
+        root.tk.call(script)
+        self.assertEqual(count, 1)
+        root.after_cancel(idle1)
+        with self.assertRaises(tkinter.TclError):
+            root.tk.call(script)
+        self.assertEqual(count, 1)
+        with self.assertRaises(tkinter.TclError):
+            root.tk.call('after', 'info', idle1)
+
 
 tests_gui = (MiscTest, )