Index: Lib/test/test_support.py
===================================================================
--- Lib/test/test_support.py	(revision 77519)
+++ Lib/test/test_support.py	(working copy)
@@ -24,7 +24,7 @@
            "fcmp", "have_unicode", "is_jython", "TESTFN", "HOST", "FUZZ",
            "findfile", "verify", "vereq", "sortdict", "check_syntax_error",
            "open_urlresource", "check_warnings", "CleanImport",
-           "EnvironmentVarGuard", "captured_output",
+           "EnvironmentVarGuard", "captured_output", "temp_cwd", "writablecwd",
            "captured_stdout", "TransientResource", "transient_internet",
            "run_with_locale", "set_memlimit", "bigmemtest", "bigaddrspacetest",
            "BasicTestRunner", "run_unittest", "run_doctest", "threading_setup",
@@ -401,6 +401,25 @@
     unlink(TESTFN)
 del fp
 
+@contextlib.contextmanager
+def temp_cwd(dirname=TESTFN+'cwd'):
+    """Create a temporary directory, and switch to it."""
+    saved_cwd = os.getcwd()
+    os.mkdir(dirname)
+    try:
+        os.chdir(dirname)
+        yield os.getcwd()
+    finally:
+        os.chdir(saved_cwd)
+        rmtree(dirname)
+
+def writablecwd(func):
+    """Decorator which switch to a writable directory."""
+    def wrapper(*args, **kw):
+        with temp_cwd():
+            func(*args, **kw)
+    return wrapper
+
 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