Issue #8716: Avoid crashes caused by Aqua Tk on OSX when attempting to run

test_tk or test_ttk_guionly under a username that is not currently logged
in to the console windowserver (as may be the case under buildbot or ssh).

Lib/lib-tk/test/runtktests.py

@@ -10,10 +10,42 @@ import os
 import sys
 import unittest
 import importlib
+import subprocess
 import test.test_support
 
 this_dir_path = os.path.abspath(os.path.dirname(__file__))
 
+_tk_available = None
+
+def check_tk_availability():
+    """Check that Tk is installed and available."""
+    global _tk_available
+
+    if _tk_available is not None:
+        return
+
+    if sys.platform == 'darwin':
+        # The Aqua Tk implementations on OS X can abort the process if
+        # being called in an environment where a window server connection
+        # cannot be made, for instance when invoked by a buildbot or ssh
+        # process not running under the same user id as the current console
+        # user.  Instead, try to initialize Tk under a subprocess.
+        p = subprocess.Popen(
+                [sys.executable, '-c', 'import Tkinter; Tkinter.Button()'],
+                stdout=subprocess.PIPE, stderr=subprocess.PIPE)
+        stderr = test.test_support.strip_python_stderr(p.communicate()[1])
+        if stderr or p.returncode:
+            raise unittest.SkipTest("tk cannot be initialized: %s" % stderr)
+    else:
+        try:
+            Tkinter.Button()
+        except tkinter.TclError as msg:
+            # assuming tk is not available
+            raise unittest.SkipTest("tk not available: %s" % msg)
+
+    _tk_available = True
+    return
+
 def is_package(path):
     for name in os.listdir(path):
         if name in ('__init__.py', '__init__.pyc', '__init.pyo'):

Lib/test/test_tk.py

@@ -1,18 +1,9 @@
 import os
-import unittest
 from test import test_support
 
 # Skip test if _tkinter wasn't built.
 test_support.import_module('_tkinter')
 
-import Tkinter
-
-try:
-    Tkinter.Button()
-except Tkinter.TclError, msg:
-    # assuming tk is not available
-    raise unittest.SkipTest("tk not available: %s" % msg)
-
 this_dir = os.path.dirname(os.path.abspath(__file__))
 lib_tk_test = os.path.abspath(os.path.join(this_dir, os.path.pardir,
     'lib-tk', 'test'))
@@ -20,6 +11,9 @@ lib_tk_test = os.path.abspath(os.path.join(this_dir, os.path.pardir,
 with test_support.DirsOnSysPath(lib_tk_test):
     import runtktests
 
+# Skip test if tk cannot be initialized.
+runtktests.check_tk_availability()
+
 def test_main(enable_gui=False):
     if enable_gui:
         if test_support.use_resources is None:

Lib/test/test_ttk_guionly.py

@@ -5,6 +5,16 @@ from test import test_support
 # Skip this test if _tkinter wasn't built.
 test_support.import_module('_tkinter')
 
+this_dir = os.path.dirname(os.path.abspath(__file__))
+lib_tk_test = os.path.abspath(os.path.join(this_dir, os.path.pardir,
+    'lib-tk', 'test'))
+
+with test_support.DirsOnSysPath(lib_tk_test):
+    import runtktests
+
+# Skip test if tk cannot be initialized.
+runtktests.check_tk_availability()
+
 import ttk
 from _tkinter import TclError
 
@@ -14,13 +24,6 @@ except TclError, msg:
     # assuming ttk is not available
     raise unittest.SkipTest("ttk not available: %s" % msg)
 
-this_dir = os.path.dirname(os.path.abspath(__file__))
-lib_tk_test = os.path.abspath(os.path.join(this_dir, os.path.pardir,
-    'lib-tk', 'test'))
-
-with test_support.DirsOnSysPath(lib_tk_test):
-    import runtktests
-
 def test_main(enable_gui=False):
     if enable_gui:
         if test_support.use_resources is None:

Misc/NEWS

@@ -83,6 +83,10 @@ Build
 Tests
 -----
 
+- Issue #8716: Avoid crashes caused by Aqua Tk on OSX when attempting to run
+  test_tk or test_ttk_guionly under a username that is not currently logged
+  in to the console windowserver (as may be the case under buildbot or ssh).
+
 - Issue #12141: Install a copy of template C module file so that
   test_build_ext of test_distutils is no longer silently skipped when
   run outside of a build directory.