bpo-6739: IDLE: Check for valid keybinding in config_keys (#2377)

Verify user-entered key sequences by trying to bind them with tk.
Add tests for all 3 validation functions.
Original patch by G Polo.  Tests added by Cheryl Sabella.

1 files changed, 44 insertions, 18 deletions

diff --git a/Lib/idlelib/config_key.py b/Lib/idlelib/config_key.py
index 479d6ad..8d575ec 100644
--- a/Lib/idlelib/config_key.py
+++ b/Lib/idlelib/config_key.py
@@ -3,11 +3,16 @@ Dialog for building Tkinter accelerator key bindings
 """
 from tkinter import *
 from tkinter.ttk import Scrollbar
-import tkinter.messagebox as tkMessageBox
+from tkinter import messagebox
 import string
 import sys
 
+
 class GetKeysDialog(Toplevel):
+
+    # Dialog title for invalid key sequence
+    keyerror_title = 'Key Sequence Error'
+
     def __init__(self, parent, title, action, currentKeySequences,
                  _htest=False, _utest=False):
         """
@@ -54,6 +59,10 @@ class GetKeysDialog(Toplevel):
             self.deiconify() #geometry set, unhide
             self.wait_window()
 
+    def showerror(self, *args, **kwargs):
+        # Make testing easier.  Replace in #30751.
+        messagebox.showerror(*args, **kwargs)
+
     def CreateWidgets(self):
         frameMain = Frame(self,borderwidth=2,relief=SUNKEN)
         frameMain.pack(side=TOP,expand=TRUE,fill=BOTH)
@@ -219,53 +228,70 @@ class GetKeysDialog(Toplevel):
         return key
 
     def OK(self, event=None):
-        if self.advanced or self.KeysOK():  # doesn't check advanced string yet
-            self.result=self.keyString.get()
-            self.destroy()
+        keys = self.keyString.get().strip()
+        if not keys:
+            self.showerror(title=self.keyerror_title, parent=self,
+                           message="No key specified.")
+            return
+        if (self.advanced or self.KeysOK(keys)) and self.bind_ok(keys):
+            self.result = keys
+        self.destroy()
 
     def Cancel(self, event=None):
         self.result=''
         self.destroy()
 
-    def KeysOK(self):
+    def KeysOK(self, keys):
         '''Validity check on user's 'basic' keybinding selection.
 
         Doesn't check the string produced by the advanced dialog because
         'modifiers' isn't set.
 
         '''
-        keys = self.keyString.get()
-        keys.strip()
         finalKey = self.listKeysFinal.get(ANCHOR)
         modifiers = self.GetModifiers()
         # create a key sequence list for overlap check:
         keySequence = keys.split()
         keysOK = False
-        title = 'Key Sequence Error'
-        if not keys:
-            tkMessageBox.showerror(title=title, parent=self,
-                                   message='No keys specified.')
-        elif not keys.endswith('>'):
-            tkMessageBox.showerror(title=title, parent=self,
-                                   message='Missing the final Key')
+        title = self.keyerror_title
+        if not keys.endswith('>'):
+            self.showerror(title, parent=self,
+                           message='Missing the final Key')
         elif (not modifiers
               and finalKey not in self.functionKeys + self.moveKeys):
-            tkMessageBox.showerror(title=title, parent=self,
-                                   message='No modifier key(s) specified.')
+            self.showerror(title=title, parent=self,
+                           message='No modifier key(s) specified.')
         elif (modifiers == ['Shift']) \
                  and (finalKey not in
                       self.functionKeys + self.moveKeys + ('Tab', 'Space')):
             msg = 'The shift modifier by itself may not be used with'\
                   ' this key symbol.'
-            tkMessageBox.showerror(title=title, parent=self, message=msg)
+            self.showerror(title=title, parent=self, message=msg)
         elif keySequence in self.currentKeySequences:
             msg = 'This key combination is already in use.'
-            tkMessageBox.showerror(title=title, parent=self, message=msg)
+            self.showerror(title=title, parent=self, message=msg)
         else:
             keysOK = True
         return keysOK
 
+    def bind_ok(self, keys):
+        "Return True if Tcl accepts the new keys else show message."
+
+        try:
+            binding = self.bind(keys, lambda: None)
+        except TclError as err:
+            self.showerror(
+                    title=self.keyerror_title, parent=self,
+                    message=(f'The entered key sequence is not accepted.\n\n'
+                             f'Error: {err}'))
+            return False
+        else:
+            self.unbind(keys, binding)
+            return True
+
 
 if __name__ == '__main__':
+    import unittest
+    unittest.main('idlelib.idle_test.test_config_key', verbosity=2, exit=False)
     from idlelib.idle_test.htest import run
     run(GetKeysDialog)