Index: Lib/test/test_support.py
===================================================================
--- Lib/test/test_support.py	(revision 78250)
+++ Lib/test/test_support.py	(working copy)
@@ -416,6 +416,38 @@
             rmtree(name)
 
 
+def any_cwd(func=None, unicode_only=False):
+    """Run the decorated test from any directory.
+
+    If optional argument "unicode_only" is True, then the test is
+    restricted to cwd which can be decoded using filesystem encoding.
+
+    Example:
+
+        @any_cwd
+        def test_something():
+            pass
+    """
+    cwdirs = [TESTFN_UNICODE.encode(TESTFN_ENCODING or "ascii", "replace")]
+    if not unicode_only:
+        cwdirs.extend([TESTFN_UNICODE.encode('latin-1'),
+                       TESTFN_UNICODE.encode('utf-8')])
+    def decorator(func):
+        @functools.wraps(func)
+        def wrapper(*args, **kwargs):
+            # First run from the current directory
+            func(*args, **kwargs)
+            # Then run from non-ASCII directories
+            for cwd in cwdirs:
+                with temp_cwd(cwd):
+                    func(*args, **kwargs)
+        return wrapper
+    if func is None:
+        return decorator
+    else:
+        return decorator(func)
+
+
 def findfile(file, here=__file__):
     """Try to find a file on sys.path and the working directory.  If it is not
     found the argument passed to the function is returned (this does not
Index: Lib/test/test_macpath.py
===================================================================
--- Lib/test/test_macpath.py	(revision 78250)
+++ Lib/test/test_macpath.py	(working copy)
@@ -5,18 +5,21 @@
 
 class MacPathTestCase(unittest.TestCase):
 
+    @test_support.any_cwd
     def test_abspath(self):
         self.assertEqual(macpath.abspath("xx:yy"), "xx:yy")
 
-        # Issue 3426: check that abspath retuns unicode when the arg is unicode
-        # and str when it's str, with both ASCII and non-ASCII cwds
-        for cwd in (u'cwd', u'\xe7w\xf0'):
-            with test_support.temp_cwd(cwd):
-                for path in ('', 'foo', 'f\xf2\xf2', '/foo', 'C:\\'):
-                    self.assertIsInstance(macpath.abspath(path), str)
-                for upath in (u'', u'fuu', u'f\xf9\xf9', u'/fuu', u'U:\\'):
-                    self.assertIsInstance(macpath.abspath(upath), unicode)
-
+        # Issue 3426: check that abspath returns bytes when the arg is bytes
+        for path in ('', 'foo', 'f\xf2\xf2', '/foo', 'C:\\'):
+            self.assertIsInstance(macpath.abspath(path), str)
+
+        self.assertRaises(TypeError, macpath.abspath)
+
+    @test_support.any_cwd(unicode_only=True)
+    def test_abspath_unicode(self):
+        # Issue 3426: check that abspath returns unicode when the arg is unicode
+        for path in (u'', u'fuu', u'f\xf9\xf9', u'/fuu', u'U:\\'):
+            self.assertIsInstance(macpath.abspath(path), unicode)
 
     def test_isabs(self):
         isabs = macpath.isabs
Index: Lib/test/test_ntpath.py
===================================================================
--- Lib/test/test_ntpath.py	(revision 78250)
+++ Lib/test/test_ntpath.py	(working copy)
@@ -154,6 +154,7 @@
             tester('ntpath.expandvars("%foo%%bar")', "bar%bar")
             tester('ntpath.expandvars("\'%foo%\'%bar")', "\'%foo%\'%bar")
 
+    @test_support.any_cwd
     def test_abspath(self):
         # ntpath.abspath() can only be used on a system with the "nt" module
         # (reasonably), so we protect this test with "import nt".  This allows
@@ -169,15 +170,20 @@
         else:
             tester('ntpath.abspath("C:\\")', "C:\\")
 
-            # Issue 3426: check that abspath retuns unicode when the arg is
-            # unicode and str when it's str, with both ASCII and non-ASCII cwds
-            for cwd in (u'cwd', u'\xe7w\xf0'):
-                with test_support.temp_cwd(cwd):
-                    for path in ('', 'foo', 'f\xf2\xf2', '/foo', 'C:\\'):
-                        self.assertIsInstance(ntpath.abspath(path), str)
-                    for upath in (u'', u'fuu', u'f\xf9\xf9', u'/fuu', u'U:\\'):
-                        self.assertIsInstance(ntpath.abspath(upath), unicode)
-
+            # Issue 3426: check that abspath returns bytes when the arg is bytes
+            for path in ('', 'foo', 'f\xf2\xf2', '/foo', 'C:\\'):
+                self.assertIsInstance(ntpath.abspath(path), str)
+
+        self.assertRaises(TypeError, ntpath.abspath)
+
+    @test_support.any_cwd(unicode_only=True)
+    def test_abspath_unicode(self):
+        # Can only be used on a system with the "nt" module
+        test_support.import_module("nt")
+
+        # Issue 3426: check that abspath returns unicode when the arg is unicode
+        for path in (u'', u'fuu', u'f\xf9\xf9', u'/fuu', u'U:\\'):
+            self.assertIsInstance(ntpath.abspath(path), unicode)
 
     def test_relpath(self):
         currentdir = os.path.split(os.getcwd())[-1]
Index: Lib/test/test_posixpath.py
===================================================================
--- Lib/test/test_posixpath.py	(revision 78250)
+++ Lib/test/test_posixpath.py	(working copy)
@@ -380,20 +380,22 @@
 
         self.assertRaises(TypeError, posixpath.normpath)
 
+    @test_support.any_cwd
     def test_abspath(self):
         self.assertIn("foo", posixpath.abspath("foo"))
 
-        # Issue 3426: check that abspath retuns unicode when the arg is unicode
-        # and str when it's str, with both ASCII and non-ASCII cwds
-        for cwd in (u'cwd', u'\xe7w\xf0'):
-            with test_support.temp_cwd(cwd):
-                for path in ('', 'foo', 'f\xf2\xf2', '/foo', 'C:\\'):
-                    self.assertIsInstance(posixpath.abspath(path), str)
-                for upath in (u'', u'fuu', u'f\xf9\xf9', u'/fuu', u'U:\\'):
-                    self.assertIsInstance(posixpath.abspath(upath), unicode)
+        # Issue 3426: check that abspath returns bytes when the arg is bytes
+        for path in ('', 'foo', 'f\xf2\xf2', '/foo', 'C:\\'):
+            self.assertIsInstance(posixpath.abspath(path), str)
 
         self.assertRaises(TypeError, posixpath.abspath)
 
+    @test_support.any_cwd(unicode_only=True)
+    def test_abspath_unicode(self):
+        # Issue 3426: check that abspath returns unicode when the arg is unicode
+        for path in (u'', u'fuu', u'f\xf9\xf9', u'/fuu', u'U:\\'):
+            self.assertIsInstance(posixpath.abspath(path), unicode)
+
     def test_realpath(self):
         self.assertIn("foo", realpath("foo"))
         self.assertRaises(TypeError, posixpath.realpath)