[3.15] gh-159127: Fix tests depending on the layout of unmapped text widgets (GH-159128) (GH-159133)

A text widget which has not been mapped yet had size 1x1 and its content
was laid out in that area, putting every character on its own display
line.  Tk no longer does this.
(cherry picked from commit 5564790)

Co-authored-by: Serhiy Storchaka <storchaka@gmail.com>

Author: miss-islington

Lib/idlelib/idle_test/test_codecontext.py

@@ -60,6 +60,8 @@ def setUpClass(cls):
         frame = cls.frame = Frame(root)
         text = cls.text = Text(frame)
         text.insert('1.0', code_sample)
+        # Make the text longer than the visible height, so that it can scroll.
+        text.insert('end', '\n' * (int(text['height']) + 2))
         # Need to pack for creation of code context text widget.
         frame.pack(side='left', fill='both', expand=1)
         text.grid(row=1, column=1, sticky=NSEW)

Lib/idlelib/idle_test/test_sidebar.py

@@ -317,6 +317,10 @@ def test_drag_selection_up(self):
         self.assertEqual(self.get_selection(), ('2.0', '5.0'))
 
     def test_scroll(self):
+        # Synchronized scrolling needs the geometry of mapped widgets.
+        self.root.deiconify()
+        self.addCleanup(self.root.withdraw)
+
         self.linenumber.show_sidebar()
         self.text.insert('1.0', 'line\n' * 100)
         self.root.update()

Lib/test/test_tkinter/test_text.py

@@ -727,10 +727,16 @@ def test_count(self):
         self.assertRaises(TclError, text.count, '1.0', 'end', 'spam')
         self.assertRaises(TclError, text.count, '1.0', 'end', '-lines')
 
-        self.assertIsInstance(text.count('1.3', '1.5', 'ypixels', return_ints=True), int)
-        self.assertIsInstance(text.count('1.3', '1.5', 'ypixels'), tuple)
-        self.assertIsInstance(text.count('1.3', '1.5', 'update', 'ypixels', return_ints=True), int)
-        self.assertIsInstance(text.count('1.3', '1.5', 'update', 'ypixels'), int)
+        # The ypixels counts depend on the widget geometry.
+        text.update()
+
+        # Indices on the same display line have zero vertical distance.
+        self.assertEqual(text.count('1.3', '1.5', 'ypixels', return_ints=True), 0)
+        self.assertIsNone(text.count('1.3', '1.5', 'ypixels'))
+        self.assertIsInstance(text.count('1.3', '2.5', 'ypixels', return_ints=True), int)
+        self.assertIsInstance(text.count('1.3', '2.5', 'ypixels'), tuple)
+        self.assertIsInstance(text.count('1.3', '2.5', 'update', 'ypixels', return_ints=True), int)
+        self.assertIsInstance(text.count('1.3', '2.5', 'update', 'ypixels'), int)
         self.assertEqual(text.count('1.3', '1.3', 'update', 'ypixels', return_ints=True), 0)
         self.assertEqual(text.count('1.3', '1.3', 'update', 'ypixels'), None)
         self.assertEqual(text.count('1.3', '1.5', 'update', 'indices', return_ints=True), 2)