[issue19602] Use specific asserts in tkinter tests

[Serhiy Storchaka]

Changes by Serhiy Storchaka <storchaka at gmail.com>:


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assignee:  -> serhiy.storchaka
resolution:  -> fixed
stage: commit review -> committed/rejected
status: open -> closed

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Python tracker <report at bugs.python.org>
<http://bugs.python.org/issue19602>
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