[Python-checkins] bpo-41306: Allow scale value to not be rounded (GH-21715) (GH-96484)

[ned-deily]

https://github.com/python/cpython/commit/bb8e49b4203fc1f2df554b452dbd3926102b18ee
commit: bb8e49b4203fc1f2df554b452dbd3926102b18ee
branch: 3.7
author: Miss Islington (bot) <31488909+miss-islington at users.noreply.github.com>
committer: ned-deily <nad at python.org>
date: 2022-09-01T15:23:27-04:00
summary:

bpo-41306: Allow scale value to not be rounded (GH-21715) (GH-96484)

This fixes the test failure with Tk 6.8.10 which is caused by changes to how Tk rounds the `from`, `to` and `tickinterval` arguments. This PR uses `noconv` if the patchlevel is greater than or equal to 8.6.10 (credit to Serhiy for this idea as it is much simpler than what I previously proposed).

Going into more detail for those who want it, the Tk change was made in [commit 591f68c](https://github.com/tcltk/tk/commit/591f68cb382525b72664c6fecaab87742b6cc87a) and means that the arguments listed above are rounded relative to the value of `from`. However, when rounding the `from` argument ([line 623](https://github.com/tcltk/tk/blob/591f68cb382525b72664c6fecaab87742b6cc87a/generic/tkScale.cGH-L623)), it is rounded relative to itself (i.e. rounding `0`) and therefore the assigned value for `from` is always what is given (no matter what values of `from` and `resolution`).

Automerge-Triggered-By: @pablogsal
(cherry picked from commit aecf036738a404371303e770f4ce4fd9f7d43de7)

Co-authored-by: E-Paine <63801254+E-Paine at users.noreply.github.com>

files:
A Misc/NEWS.d/next/Tests/2020-08-03-13-44-37.bpo-41306.VDoWXI.rst
M Lib/tkinter/test/test_tkinter/test_widgets.py

diff --git a/Lib/tkinter/test/test_tkinter/test_widgets.py b/Lib/tkinter/test/test_tkinter/test_widgets.py
index 3fb641108cf8..5cfab683205d 100644
--- a/Lib/tkinter/test/test_tkinter/test_widgets.py
+++ b/Lib/tkinter/test/test_tkinter/test_widgets.py
@@ -864,7 +864,8 @@ def test_digits(self):
 
     def test_from(self):
         widget = self.create()
-        self.checkFloatParam(widget, 'from', 100, 14.9, 15.1, conv=float_round)
+        conv = False if get_tk_patchlevel() >= (8, 6, 10) else float_round
+        self.checkFloatParam(widget, 'from', 100, 14.9, 15.1, conv=conv)
 
     def test_label(self):
         widget = self.create()
diff --git a/Misc/NEWS.d/next/Tests/2020-08-03-13-44-37.bpo-41306.VDoWXI.rst b/Misc/NEWS.d/next/Tests/2020-08-03-13-44-37.bpo-41306.VDoWXI.rst
new file mode 100644
index 000000000000..5e9ba2d8a274
--- /dev/null
+++ b/Misc/NEWS.d/next/Tests/2020-08-03-13-44-37.bpo-41306.VDoWXI.rst
@@ -0,0 +1 @@
+Fixed a failure in ``test_tk.test_widgets.ScaleTest`` happening when executing the test with Tk 8.6.10.