test_ttk_guionly runs test_identify, doesn't it?  (I'll try to take a look at it later when I have more time.)

$ /usr/local/bin/python3.5 -m test -vu gui test_ttk_guionly
== CPython 3.5.2rc1 (v3.5.2rc1:68feec6488b2, Jun 11 2016, 21:59:53) [GCC 4.2.1 (Apple Inc. build 5666) (dot 3)]
==   Darwin-15.5.0-x86_64-i386-64bit little-endian
==   hash algorithm: siphash24 64bit
Testing with flags: sys.flags(debug=0, inspect=0, interactive=0, optimize=0, dont_write_bytecode=0, no_user_site=0, no_site=0, ignore_environment=0, verbose=0, bytes_warning=0, quiet=0, hash_randomization=1, isolated=0)
[1/1] test_ttk_guionly
test_horizontal_range (tkinter.test.test_ttk.test_extensions.LabeledScaleTest) ... ok
test_initialization (tkinter.test.test_ttk.test_extensions.LabeledScaleTest) ... ok
test_initialization_no_master (tkinter.test.test_ttk.test_extensions.LabeledScaleTest) ... ok
test_resize (tkinter.test.test_ttk.test_extensions.LabeledScaleTest) ... ok
test_variable_change (tkinter.test.test_ttk.test_extensions.LabeledScaleTest) ... ok
test_widget_destroy (tkinter.test.test_ttk.test_extensions.LabeledScaleTest) ... ok
test_initialization (tkinter.test.test_ttk.test_extensions.OptionMenuTest) ... ok
test_menu (tkinter.test.test_ttk.test_extensions.OptionMenuTest) ... ok
test_widget_destroy (tkinter.test.test_ttk.test_extensions.OptionMenuTest) ... ok
test_configure (tkinter.test.test_ttk.test_style.StyleTest) ... ok
test_layout (tkinter.test.test_ttk.test_style.StyleTest) ... ok
test_lookup (tkinter.test.test_ttk.test_style.StyleTest) ... ok
test_map (tkinter.test.test_ttk.test_style.StyleTest) ... ok
test_theme_use (tkinter.test.test_ttk.test_style.StyleTest) ... ok
patchlevel = 8.5.18
[...]
test_foreground (tkinter.test.test_ttk.test_widgets.ComboboxTest) ... ok
test_height (tkinter.test.test_ttk.test_widgets.ComboboxTest) ... ok
test_identify (tkinter.test.test_ttk.test_widgets.ComboboxTest) ... FAIL
test_invalidcommand (tkinter.test.test_ttk.test_widgets.ComboboxTest) ... ok
test_justify (tkinter.test.test_ttk.test_widgets.ComboboxTest) ... ok
test_keys (tkinter.test.test_ttk.test_widgets.ComboboxTest) ... ok
test_postcommand (tkinter.test.test_ttk.test_widgets.ComboboxTest) ... ok
[...]
test_validatecommand (tkinter.test.test_ttk.test_widgets.ComboboxTest) ... ok
test_validation (tkinter.test.test_ttk.test_widgets.ComboboxTest) ... ok
test_validation_options (tkinter.test.test_ttk.test_widgets.ComboboxTest) ... ok
test_values (tkinter.test.test_ttk.test_widgets.ComboboxTest) ... ok
test_virtual_event (tkinter.test.test_ttk.test_widgets.ComboboxTest) ... FAIL
test_width (tkinter.test.test_ttk.test_widgets.ComboboxTest) ... ok
test_xscrollcommand (tkinter.test.test_ttk.test_widgets.ComboboxTest) ... ok
test_background (tkinter.test.test_ttk.test_widgets.EntryTest) ... ok
[...]
test_identify (tkinter.test.test_ttk.test_widgets.WidgetTest) ... ok
test_widget_state (tkinter.test.test_ttk.test_widgets.WidgetTest) ... ok

======================================================================
FAIL: test_identify (tkinter.test.test_ttk.test_widgets.ComboboxTest)
----------------------------------------------------------------------
Traceback (most recent call last):
  File "/Library/Frameworks/Python.framework/Versions/3.5/lib/python3.5/tkinter/test/test_ttk/test_widgets.py", line 332, in test_identify
    self.assertEqual(self.entry.identify(5, 5), "textarea")
AssertionError: 'Combobox.button' != 'textarea'
- Combobox.button
+ textarea


======================================================================
FAIL: test_virtual_event (tkinter.test.test_ttk.test_widgets.ComboboxTest)
----------------------------------------------------------------------
Traceback (most recent call last):
  File "/Library/Frameworks/Python.framework/Versions/3.5/lib/python3.5/tkinter/test/test_ttk/test_widgets.py", line 455, in test_virtual_event
    self.assertTrue(success)
AssertionError: [] is not true

----------------------------------------------------------------------
Ran 271 tests in 3.242s

FAILED (failures=2, skipped=11)
test test_ttk_guionly failed
1 test failed:
    test_ttk_guionly