1 files changed, 46 insertions, 0 deletions
diff --git a/Lib/tkinter/test/support.py b/Lib/tkinter/test/support.py
index 97212fb..6dd6d4a 100644
--- a/Lib/tkinter/test/support.py
+++ b/Lib/tkinter/test/support.py
@@ -1,6 +1,52 @@
+import sys
 import tkinter
+import unittest
+
+_tk_unavailable = None
+
+def check_tk_availability():
+    """Check that Tk is installed and available."""
+    global _tk_unavailable
+
+    if _tk_unavailable is None:
+        _tk_unavailable = False
+        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.  To avoid that, raise an exception if the window manager
+            # connection is not available.
+            from ctypes import cdll, c_int, pointer, Structure
+            from ctypes.util import find_library
+
+            app_services = cdll.LoadLibrary(find_library("ApplicationServices"))
+
+            if app_services.CGMainDisplayID() == 0:
+                _tk_unavailable = "cannot run without OS X window manager"
+            else:
+                class ProcessSerialNumber(Structure):
+                    _fields_ = [("highLongOfPSN", c_int),
+                                ("lowLongOfPSN", c_int)]
+                psn = ProcessSerialNumber()
+                psn_p = pointer(psn)
+                if (  (app_services.GetCurrentProcess(psn_p) < 0) or
+                      (app_services.SetFrontProcess(psn_p) < 0) ):
+                    _tk_unavailable = "cannot run without OS X gui process"
+        else:   # not OS X
+            import tkinter
+            try:
+                tkinter.Button()
+            except tkinter.TclError as msg:
+                # assuming tk is not available
+                _tk_unavailable = "tk not available: %s" % msg
+
+    if _tk_unavailable:
+        raise unittest.SkipTest(_tk_unavailable)
+    return
 
 def get_tk_root():
+    check_tk_availability()     # raise exception if tk unavailable
     try:
         root = tkinter._default_root
     except AttributeError: