[3.15] gh-69134: Harden tkinter GUI tests that depend on a mapped widget (GH-152499) (GH-152516)

Add wait_until_mapped() and AbstractTkTest.require_mapped() to
test_tkinter.support and use them to guard the assertions that need a
widget to be actually mapped (winfo_width(), identify(), coords(), ...).
This avoids intermittent failures under window managers that do not map
the widget promptly, without skipping the unrelated checks.
(cherry picked from commit 0fff6bd)
Co-authored-by: Serhiy Storchaka <storchaka@gmail.com>
Co-authored-by: Claude Opus 4.8 <noreply@anthropic.com>

Author: 3 people

Lib/test/test_tkinter/support.py

@@ -1,4 +1,5 @@
 importfunctools
+importtime
 importtkinter
 importunittest
 fromtestimportsupport
@@ -45,6 +46,20 @@ def tearDown(self):
 w.destroy()
 self.root.withdraw()
 
+defrequire_mapped(self, widget, timeout=None):
+"""Realize *widget*, or skip the test if the window manager will
+ not map it (e.g. a tiling WM or a headless/contended display).
+
+ Use this instead of a bare update() before querying realized
+ geometry (winfo_width(), identify(), coords(), place_info(), ...).
+ See gh-69134, gh-74941 and bpo-40722.
+ """
+iftimeoutisNone:
+timeout=support.LOOPBACK_TIMEOUT
+ifnotwait_until_mapped(widget, timeout):
+self.skipTest('widget was not mapped by the window manager '
+f'(timed out after {timeout:g}s)')
+
 
 classAbstractDefaultRootTest:
 
@@ -78,6 +93,32 @@ def destroy_default_root():
 tkinter._default_root.destroy()
 tkinter._default_root=None
 
+defwait_until_mapped(widget, timeout=None):
+"""Wait until *widget* is actually mapped and laid out by the window
+ manager, so that realized-geometry queries (winfo_width(), identify(),
+ coords(), ...) return meaningful values.
+
+ Return True once the widget is mapped with a non-trivial size, or False
+ if that has not happened within *timeout* seconds (default:
+ ``support.LOOPBACK_TIMEOUT``). Unlike Misc.wait_visibility(), this
+ never blocks indefinitely, so it is safe under a window manager that
+ never maps the window (see gh-69134, gh-74941, bpo-40722).
+ """
+iftimeoutisNone:
+timeout=support.LOOPBACK_TIMEOUT
+deadline=time.monotonic() +timeout
+widget.update_idletasks()
+whileTrue:
+widget.update() # drain pending Map/Configure events
+if (widget.winfo_ismapped()
+andwidget.winfo_width() >1
+andwidget.winfo_height() >1):
+returnTrue
+iftime.monotonic() >=deadline:
+returnFalse
+time.sleep(0.01)
+
+
 defsimulate_mouse_click(widget, x, y):
 """Generate proper events to click at the x, y position (tries to act
  like an X server)."""

Lib/test/test_tkinter/test_widgets.py

@@ -7,6 +7,7 @@
 fromtest.test_tkinter.supportimportsetUpModule# noqa: F401
 fromtest.test_tkinter.supportimport (requires_tk, tk_version,
 get_tk_patchlevel, widget_eq,
+wait_until_mapped,
 AbstractDefaultRootTest)
 
 fromtest.test_tkinter.widget_testsimport (
@@ -754,10 +755,11 @@ def test_invoke(self):
 deftest_identify(self):
 widget=self.create()
 widget.pack()
-widget.update_idletasks()
-# The empty string is returned for a point over no element.
-self.assertIn(widget.identify(5, 5),
- ('entry', 'buttonup', 'buttondown', 'none', ''))
+# Identifying the element under a point requires the widget to be
+# mapped with a real size.
+ifwait_until_mapped(widget):
+self.assertIn(widget.identify(5, 5),
+ ('entry', 'buttonup', 'buttondown', 'none'))
 self.assertRaises(TclError, widget.identify, 'a', 'b')
 
 deftest_scan(self):
@@ -2096,9 +2098,11 @@ def test_delta(self):
 deftest_identify(self):
 sb=self.create()
 sb.pack(fill='y', expand=True)
-sb.update_idletasks()
-self.assertIn(sb.identify(5, 5),
- ('arrow1', 'arrow2', 'slider', 'trough1', 'trough2', ''))
+# Identifying the element under a point requires the widget to be
+# mapped with a real size.
+ifwait_until_mapped(sb):
+self.assertIn(sb.identify(5, 5),
+ ('arrow1', 'arrow2', 'slider', 'trough1', 'trough2'))
 self.assertRaises(TclError, sb.identify, 'a', 'b')
 
 
@@ -2218,10 +2222,12 @@ def test_identify(self):
 p, b, c=self.create2()
 p.configure(width=200, height=50)
 p.pack()
-p.update()
-x, y=p.sash_coord(0)
-# A point over the sash reports the sash.
-self.assertIn('sash', p.identify(x+1, y+5))
+# Locating the sash requires the widget to be mapped with a real
+# size; the rest of the checks do not.
+ifwait_until_mapped(p):
+x, y=p.sash_coord(0)
+# A point over the sash reports the sash.
+self.assertIn('sash', p.identify(x+1, y+5))
 # A point over a pane reports nothing.
 self.assertFalse(p.identify(2, 2))
 self.assertRaises(TclError, p.identify, 'a', 'b')

Lib/test/test_ttk/test_extensions.py

@@ -109,7 +109,7 @@ def check_positions(scale, scale_pos, label, label_pos):
 deftest_horizontal_range(self):
 lscale=ttk.LabeledScale(self.root, from_=0, to=10)
 lscale.pack()
-lscale.update()
+self.require_mapped(lscale)
 
 linfo_1=lscale.label.place_info()
 prev_xcoord=lscale.scale.coords()[0]
@@ -138,7 +138,7 @@ def test_horizontal_range(self):
 deftest_variable_change(self):
 x=ttk.LabeledScale(self.root)
 x.pack()
-x.update()
+self.require_mapped(x)
 
 curr_xcoord=x.scale.coords()[0]
 newval=x.value+1
@@ -181,7 +181,7 @@ def test_resize(self):
 x=ttk.LabeledScale(self.root)
 x.pack(expand=True, fill='both')
 gc_collect() # For PyPy or other GCs.
-x.update()
+self.require_mapped(x)
 
 width, height=x.master.winfo_width(), x.master.winfo_height()
 width_new, height_new=width*2, height*2

Lib/test/test_ttk/test_widgets.py

@@ -8,7 +8,7 @@
 fromtest.test_tkinter.supportimportsetUpModule# noqa: F401
 fromtest.test_tkinter.supportimport (
 AbstractTkTest, requires_tk, tk_version, get_tk_patchlevel,
-simulate_mouse_click, AbstractDefaultRootTest)
+simulate_mouse_click, wait_until_mapped, AbstractDefaultRootTest)
 fromtest.test_tkinter.widget_testsimport (add_configure_tests,
 AbstractWidgetTest, StandardOptionsTests, IntegerSizeTests, PixelSizeTests)
 
@@ -78,11 +78,13 @@ def setUp(self):
 self.widget.pack()
 
 deftest_identify(self):
-self.widget.update()
-self.assertEqual(self.widget.identify(
-int(self.widget.winfo_width() /2),
-int(self.widget.winfo_height() /2)
- ), "label")
+# Identifying the element under a point requires the widget to be
+# mapped with a real size; the rest of the checks do not.
+ifwait_until_mapped(self.widget):
+self.assertEqual(self.widget.identify(
+int(self.widget.winfo_width() /2),
+int(self.widget.winfo_height() /2)
+ ), "label")
 self.assertEqual(self.widget.identify(-1, -1), "")
 
 self.assertRaises(tkinter.TclError, self.widget.identify, None, 5)
@@ -385,9 +387,11 @@ def test_identify(self):
 self.skipTest('Test does not work on macOS Tk 9.')
 # https://core.tcl-lang.org/tk/tktview/8b49e9cfa6
 self.entry.pack()
-self.root.update()
 
-self.assertIn(self.entry.identify(5, 5), self.IDENTIFY_AS)
+# Identifying the element under a point requires the widget to be
+# mapped with a real size; the rest of the checks do not.
+ifwait_until_mapped(self.entry):
+self.assertIn(self.entry.identify(5, 5), self.IDENTIFY_AS)
 self.assertEqual(self.entry.identify(-1, -1), "")
 
 self.assertRaises(tkinter.TclError, self.entry.identify, None, 5)
@@ -506,7 +510,7 @@ def test_virtual_event(self):
 self.combo.bind('<<ComboboxSelected>>',
 lambdaevt: success.append(True))
 self.combo.pack()
-self.combo.update()
+self.require_mapped(self.combo)
 
 height=self.combo.winfo_height()
 self._show_drop_down_listbox()
@@ -525,7 +529,7 @@ def test_configure_postcommand(self):
 
 self.combo['postcommand'] =lambda: success.append(True)
 self.combo.pack()
-self.combo.update()
+self.require_mapped(self.combo)
 
 self._show_drop_down_listbox()
 self.assertTrue(success)
@@ -875,8 +879,10 @@ def test_get(self):
 else:
 conv=float
 
-scale_width=self.scale.winfo_width()
-self.assertEqual(self.scale.get(scale_width, 0), self.scale['to'])
+# Reading the value at the far edge needs the realized width.
+ifwait_until_mapped(self.scale):
+scale_width=self.scale.winfo_width()
+self.assertEqual(self.scale.get(scale_width, 0), self.scale['to'])
 
 self.assertEqual(conv(self.scale.get(0, 0)), conv(self.scale['from']))
 self.assertEqual(self.scale.get(), self.scale['value'])
@@ -918,7 +924,10 @@ def test_set(self):
 # nevertheless, note that the max/min values we can get specifying
 # x, y coords are the ones according to the current range
 self.assertEqual(conv(self.scale.get(0, 0)), min)
-self.assertEqual(conv(self.scale.get(self.scale.winfo_width(), 0)), max)
+# Reading the value at the far edge needs the realized width.
+ifwait_until_mapped(self.scale):
+self.assertEqual(
+conv(self.scale.get(self.scale.winfo_width(), 0)), max)
 
 self.assertRaises(tkinter.TclError, self.scale.set, None)
 
@@ -1269,6 +1278,7 @@ def create(self, **kwargs):
 returnttk.Spinbox(self.root, **kwargs)
 
 def_click_increment_arrow(self):
+self.require_mapped(self.spin)
 width=self.spin.winfo_width()
 height=self.spin.winfo_height()
 x=width-5
@@ -1279,6 +1289,7 @@ def _click_increment_arrow(self):
 self.spin.update_idletasks()
 
 def_click_decrement_arrow(self):
+self.require_mapped(self.spin)
 width=self.spin.winfo_width()
 height=self.spin.winfo_height()
 x=width-5