bpo-37902: IDLE: Add scrolling for IDLE browsers. (#15368)

Modify the wheel event handler so it can also be used for module, path, and stack browsers.
Patch by George Zhang.

2 files changed, 36 insertions, 1 deletions

diff --git a/Lib/idlelib/idle_test/test_multicall.py b/Lib/idlelib/idle_test/test_multicall.py
index 68156a743d..ba582bb3ca 100644
--- a/Lib/idlelib/idle_test/test_multicall.py
+++ b/Lib/idlelib/idle_test/test_multicall.py
@@ -35,6 +35,14 @@ class MultiCallTest(unittest.TestCase):
         mctext = self.mc(self.root)
         self.assertIsInstance(mctext._MultiCall__binders, list)
 
+    def test_yview(self):
+        # Added for tree.wheel_event
+        # (it depends on yview to not be overriden)
+        mc = self.mc
+        self.assertIs(mc.yview, Text.yview)
+        mctext = self.mc(self.root)
+        self.assertIs(mctext.yview.__func__, Text.yview)
+
 
 if __name__ == '__main__':
     unittest.main(verbosity=2)
diff --git a/Lib/idlelib/idle_test/test_tree.py b/Lib/idlelib/idle_test/test_tree.py
index 9be9abee36..b3e4c10cf9 100644
--- a/Lib/idlelib/idle_test/test_tree.py
+++ b/Lib/idlelib/idle_test/test_tree.py
@@ -4,7 +4,7 @@ from idlelib import tree
 import unittest
 from test.support import requires
 requires('gui')
-from tkinter import Tk
+from tkinter import Tk, EventType, SCROLL
 
 
 class TreeTest(unittest.TestCase):
@@ -29,5 +29,32 @@ class TreeTest(unittest.TestCase):
         node.expand()
 
 
+class TestScrollEvent(unittest.TestCase):
+
+    def test_wheel_event(self):
+        # Fake widget class containing `yview` only.
+        class _Widget:
+            def __init__(widget, *expected):
+                widget.expected = expected
+            def yview(widget, *args):
+                self.assertTupleEqual(widget.expected, args)
+        # Fake event class
+        class _Event:
+            pass
+        #        (type, delta, num, amount)
+        tests = ((EventType.MouseWheel, 120, -1, -5),
+                 (EventType.MouseWheel, -120, -1, 5),
+                 (EventType.ButtonPress, -1, 4, -5),
+                 (EventType.ButtonPress, -1, 5, 5))
+
+        event = _Event()
+        for ty, delta, num, amount in tests:
+            event.type = ty
+            event.delta = delta
+            event.num = num
+            res = tree.wheel_event(event, _Widget(SCROLL, amount, "units"))
+            self.assertEqual(res, "break")
+
+
 if __name__ == '__main__':
     unittest.main(verbosity=2)