[3.11] IDLE: Fix test_debugger bug and buildbot failures (GH-112258) (#112260)

IDLE: Fix test_debugger bug and buildbot failures (GH-112258)

Missing "requires('gui')" causes Tk() to fail when no gui.
This caused CI Hypothesis test to fail, but I did not understand
the its error message. Then buildbots failed.

IdbTest failed on draft Bdb replacement because so different.
Simplified version works on old and new.
(cherry picked from commit 14fd86a59d)

Co-authored-by: Terry Jan Reedy <tjreedy@udel.edu>

Lib/idlelib/idle_test/test_debugger.py

@@ -1,4 +1,7 @@
-"Test debugger, coverage 19%"
+"""Test debugger, coverage 66%
+
+Try to make tests pass with draft bdbx, which may replace bdb in 3.13+.
+"""
 
 from idlelib import debugger
 from collections import namedtuple
@@ -44,10 +47,8 @@ def setUpClass(cls):
         cls.msg = 'file.py:2: <module>()'
 
     def test_init(self):
-        # Test that Idb.__init_ calls Bdb.__init__.
-        idb = debugger.Idb(None)
-        self.assertIsNone(idb.gui)
-        self.assertTrue(hasattr(idb, 'breaks'))
+        self.assertIs(self.idb.gui, self.gui)
+        # Won't test super call since two Bdbs are very different.
 
     def test_user_line(self):
         # Test that .user_line() creates a string message for a frame.
@@ -279,6 +280,7 @@ class NameSpaceTest(unittest.TestCase):
 
     @classmethod
     def setUpClass(cls):
+        requires('gui')
         cls.root = Tk()
         cls.root.withdraw()