/usr/lib/python3.5/tkinter/ is in libpython3.5-testsuite 3.5.1-10.
This file is owned by root:root, with mode 0o755.
..
/usr/lib/python3.5/tkinter/test/
/usr/lib/python3.5/tkinter/test/README
/usr/lib/python3.5/tkinter/test/__init__.py
/usr/lib/python3.5/tkinter/test/runtktests.py
/usr/lib/python3.5/tkinter/test/support.py
/usr/lib/python3.5/tkinter/test/test_tkinter/
/usr/lib/python3.5/tkinter/test/test_tkinter/__init__.py
/usr/lib/python3.5/tkinter/test/test_tkinter/test_font.py
/usr/lib/python3.5/tkinter/test/test_tkinter/test_geometry_managers.py
/usr/lib/python3.5/tkinter/test/test_tkinter/test_images.py
/usr/lib/python3.5/tkinter/test/test_tkinter/test_loadtk.py
/usr/lib/python3.5/tkinter/test/test_tkinter/test_misc.py
/usr/lib/python3.5/tkinter/test/test_tkinter/test_text.py
/usr/lib/python3.5/tkinter/test/test_tkinter/test_variables.py
/usr/lib/python3.5/tkinter/test/test_tkinter/test_widgets.py
/usr/lib/python3.5/tkinter/test/test_ttk/
/usr/lib/python3.5/tkinter/test/test_ttk/__init__.py
/usr/lib/python3.5/tkinter/test/test_ttk/test_extensions.py
/usr/lib/python3.5/tkinter/test/test_ttk/test_functions.py
/usr/lib/python3.5/tkinter/test/test_ttk/test_style.py
/usr/lib/python3.5/tkinter/test/test_ttk/test_widgets.py
/usr/lib/python3.5/tkinter/test/widget_tests.py