bpo-37706: Disable 3 IDLE scrollbar tests on Mac. (python#15010)

They pass with tk 8.5.9 (Azure) but fail with the 8.6.x we install.

Author: terryjreedy

Lib/idlelib/idle_test/test_sidebar.py

@@ -1,4 +1,6 @@
 """Test sidebar, coverage 93%"""
+import idlelib.sidebar
+from sys import platform
 from itertools import chain
 import unittest
 import unittest.mock
@@ -7,7 +9,6 @@
 
 from idlelib.delegator import Delegator
 from idlelib.percolator import Percolator
-import idlelib.sidebar
 
 
 class Dummy_editwin:
@@ -239,6 +240,7 @@ def get_width():
         self.assert_sidebar_n_lines(1)
         self.assertEqual(get_width(), 1)
 
+    @unittest.skipIf(platform == 'darwin', 'test tk version dependent')
     def test_click_selection(self):
         self.linenumber.show_sidebar()
         self.text.insert('1.0', 'one\ntwo\nthree\nfour\n')
@@ -252,14 +254,15 @@ def test_click_selection(self):
 
         self.assertEqual(self.get_selection(), ('2.0', '3.0'))
 
-    def test_drag_selection(self):
+    @unittest.skipIf(platform == 'darwin', 'test tk version dependent')
+    def test_drag_selection_down(self):
         self.linenumber.show_sidebar()
-        self.text.insert('1.0', 'one\ntwo\nthree\nfour\n')
+        self.text.insert('1.0', 'one\ntwo\nthree\nfour\nfive\n')
         self.root.update()
 
-        # Drag from the first line to the third line.
-        start_x, start_y = self.get_line_screen_position(1)
-        end_x, end_y = self.get_line_screen_position(3)
+        # Drag from the second line to the fourth line.
+        start_x, start_y = self.get_line_screen_position(2)
+        end_x, end_y = self.get_line_screen_position(4)
         self.linenumber.sidebar_text.event_generate('<Button-1>',
                                                     x=start_x, y=start_y)
         self.linenumber.sidebar_text.event_generate('<B1-Motion>',
@@ -269,8 +272,27 @@ def test_drag_selection(self):
         self.linenumber.sidebar_text.event_generate('<ButtonRelease-1>',
                                                     x=end_x, y=end_y)
         self.root.update()
+        self.assertEqual(self.get_selection(), ('2.0', '5.0'))
+
+    @unittest.skipIf(platform == 'darwin', 'test tk version dependent')
+    def test_drag_selection_up(self):
+        self.linenumber.show_sidebar()
+        self.text.insert('1.0', 'one\ntwo\nthree\nfour\nfive\n')
+        self.root.update()
 
-        self.assertEqual(self.get_selection(), ('1.0', '4.0'))
+        # Drag from the fourth line to the second line.
+        start_x, start_y = self.get_line_screen_position(4)
+        end_x, end_y = self.get_line_screen_position(2)
+        self.linenumber.sidebar_text.event_generate('<Button-1>',
+                                                    x=start_x, y=start_y)
+        self.linenumber.sidebar_text.event_generate('<B1-Motion>',
+                                                    x=start_x, y=start_y)
+        self.linenumber.sidebar_text.event_generate('<B1-Motion>',
+                                                    x=end_x, y=end_y)
+        self.linenumber.sidebar_text.event_generate('<ButtonRelease-1>',
+                                                    x=end_x, y=end_y)
+        self.root.update()
+        self.assertEqual(self.get_selection(), ('2.0', '5.0'))
 
     def test_scroll(self):
         self.linenumber.show_sidebar()