(Merge 3.2) Close #12230: Mac OS X Tiger (10.4) has a kernel bug: sometimes,

the file descriptor of a pipe closed in the parent process is valid in the
child process according to fstat(), but the mode of the file descriptor is
invalid, and read or write raise an error.

test.support.requires_mac_ver() is now a decorator, as suggested by Ezio
Melotti, and its docstring is fixed (linux_version => mac_ver).

Lib/test/support.py

@@ -301,23 +301,32 @@ def linux_version():
         return 0, 0, 0
 
 def requires_mac_ver(*min_version):
-    """Raise SkipTest if the OS is Mac OS X and the OS X version if less than
-    min_version.
+    """Decorator raising SkipTest if the OS is Mac OS X and the OS X
+    version if less than min_version.
 
-    For example, support.requires_linux_version(10, 5) raises SkipTest if the
-    version is less than 10.5.
+    For example, @requires_mac_ver(10, 5) raises SkipTest if the OS X version
+    is lesser than 10.5.
     """
-    if sys.platform != 'darwin':
-        return
-    version_txt = platform.mac_ver()[0]
-    try:
-        version = tuple(map(int, version_txt.split('.')))
-    except ValueError:
-        return
-    if version < min_version:
-        min_version_txt = '.'.join(map(str, min_version))
-        raise unittest.SkipTest("Mac OS X %s or higher required, not %s"
-                                % (min_version_txt, version_txt))
+    def decorator(func):
+        @functools.wraps(func)
+        def wrapper(*args, **kw):
+            if sys.platform == 'darwin':
+                version_txt = platform.mac_ver()[0]
+                try:
+                    version = tuple(map(int, version_txt.split('.')))
+                except ValueError:
+                    pass
+                else:
+                    if version < min_version:
+                        min_version_txt = '.'.join(map(str, min_version))
+                        raise unittest.SkipTest(
+                            "Mac OS X %s or higher required, not %s"
+                            % (min_version_txt, version_txt))
+            return func(*args, **kw)
+        wrapper.min_version = min_version
+        return wrapper
+    return decorator
+
 
 HOST = 'localhost'
 

Lib/test/test_math.py

@@ -670,10 +670,9 @@ class MathTests(unittest.TestCase):
         self.assertTrue(math.isnan(math.log2(NAN)))
 
     @requires_IEEE_754
+    # log2() is not accurate enough on Mac OS X Tiger (10.4)
+    @support.requires_mac_ver(10, 5)
     def testLog2Exact(self):
-        # log2() is not accurate enough on Mac OS X Tiger (10.4)
-        support.requires_mac_ver(10, 5)
-
         # Check that we get exact equality for log2 of powers of 2.
         actual = [math.log2(math.ldexp(1.0, n)) for n in range(-1074, 1024)]
         expected = [float(n) for n in range(-1074, 1024)]

Lib/test/test_subprocess.py

@@ -1281,6 +1281,11 @@ class POSIXProcessTestCase(BaseTestCase):
                          "Some fds were left open")
         self.assertIn(1, remaining_fds, "Subprocess failed")
 
+    # Mac OS X Tiger (10.4) has a kernel bug: sometimes, the file
+    # descriptor of a pipe closed in the parent process is valid in the
+    # child process according to fstat(), but the mode of the file
+    # descriptor is invalid, and read or write raise an error.
+    @support.requires_mac_ver(10, 5)
     def test_pass_fds(self):
         fd_status = support.findfile("fd_status.py", subdir="subprocessdata")