bpo-28009: Fix SkipUnless logic to be based on platform programs capable of introspection

Lib/test/test_uuid.py

@@ -462,8 +462,7 @@ def test_uuid1_eui64(self):
         with unittest.mock.patch.multiple(
             self.uuid,
             _node=None,  # Ignore any cached node value.
-            _NODE_GETTERS_WIN32=[too_large_getter],
-            _NODE_GETTERS_UNIX=[too_large_getter],
+            _NODE_GETTERS=[too_large_getter],
         ):
             node = self.uuid.getnode()
         self.assertTrue(0 < node < (1 << 48), '%012x' % node)
@@ -673,7 +672,7 @@ class TestUUIDWithExtModule(BaseTestUUID, unittest.TestCase):
 
 
 class BaseTestInternals:
-    uuid = None
+    _uuid = py_uuid
 
     @unittest.skipUnless(os.name == 'posix', 'requires Posix')
     def test_find_mac(self):
@@ -708,27 +707,32 @@ def check_node(self, node, requires=None):
         self.assertTrue(0 < node < (1 << 48),
                         "%s is not an RFC 4122 node ID" % hex)
 
-    @unittest.skipUnless(os.name == 'posix', 'requires Posix')
+    @unittest.skipUnless(_uuid._ifconfig_getnode in _uuid._NODE_GETTERS,
+        "ifconfig is not used for introspection on this platform")
     def test_ifconfig_getnode(self):
         node = self.uuid._ifconfig_getnode()
         self.check_node(node, 'ifconfig')
 
-    @unittest.skipUnless(os.name == 'posix', 'requires Posix')
+    @unittest.skipUnless(_uuid._ip_getnode in _uuid._NODE_GETTERS,
+        "ip is not used for introspection on this platform")
     def test_ip_getnode(self):
         node = self.uuid._ip_getnode()
         self.check_node(node, 'ip')
 
-    @unittest.skipUnless(os.name == 'posix', 'requires Posix')
+    @unittest.skipUnless(_uuid._arp_getnode in _uuid._NODE_GETTERS,
+        "arp is not used for introspection on this platform")
     def test_arp_getnode(self):
         node = self.uuid._arp_getnode()
         self.check_node(node, 'arp')
 
-    @unittest.skipUnless(os.name == 'posix', 'requires Posix')
+    @unittest.skipUnless(_uuid._lanscan_getnode in _uuid._NODE_GETTERS,
+        "lanscan is not used for introspection on this platform")
     def test_lanscan_getnode(self):
         node = self.uuid._lanscan_getnode()
         self.check_node(node, 'lanscan')
 
-    @unittest.skipUnless(os.name == 'posix', 'requires Posix')
+    @unittest.skipUnless(_uuid._netstat_getnode in _uuid._NODE_GETTERS,
+        "netstat is not used for introspection on this platform")
     def test_netstat_getnode(self):
         node = self.uuid._netstat_getnode()
         self.check_node(node, 'netstat')

Lib/uuid.py

@@ -45,13 +45,20 @@
 """
 
 import os
+import platform
 import sys
 
 from enum import Enum
 
 
 __author__ = 'Ka-Ping Yee <ping@zesty.ca>'
 
+# The recognized platforms - known behaviors
+_AIX     = platform.system() == 'AIX'
+_DARWIN  = platform.system() == 'Darwin'
+_LINUX   = platform.system() == 'Linux'
+_WINDOWS = platform.system() == 'Windows'
+
 RESERVED_NCS, RFC_4122, RESERVED_MICROSOFT, RESERVED_FUTURE = [
     'reserved for NCS compatibility', 'specified in RFC 4122',
     'reserved for Microsoft compatibility', 'reserved for future definition']
@@ -673,12 +680,26 @@ def _random_getnode():
     return random.getrandbits(48) | (1 << 40)
 
 
-_node = None
-
-_NODE_GETTERS_WIN32 = [_windll_getnode, _netbios_getnode, _ipconfig_getnode]
+if _LINUX:
+    _GETTERS = [_ifconfig_getnode, _ip_getnode,
+                          _arp_getnode, _lanscan_getnode]
+elif _DARWIN:
+    _GETTERS = [_arp_getnode, _ifconfig_getnode, _netstat_getnode]
+elif _WINDOWS:
+    _GETTERS = [_windll_getnode, _netbios_getnode, _ipconfig_getnode]
+elif _AIX:
+    _GETTERS = [_netstat_getnode]
+else:
+    _GETTERS = [_ifconfig_getnode, _ip_getnode,
+                          _arp_getnode, _lanscan_getnode, _netstat_getnode]
+if os.name == 'posix':
+    _NODE_GETTERS = [_unix_getnode] + _GETTERS
+elif os.name == 'nt':
+    _NODE_GETTERS = [_windll_getnode] + _GETTERS
+else:
+    _NODE_GETTERS = _GETTERS
 
-_NODE_GETTERS_UNIX = [_unix_getnode, _ifconfig_getnode, _ip_getnode,
-                      _arp_getnode, _lanscan_getnode, _netstat_getnode]
+_node = None
 
 def getnode(*, getters=None):
     """Get the hardware address as a 48-bit positive integer.
@@ -692,12 +713,7 @@ def getnode(*, getters=None):
     if _node is not None:
         return _node
 
-    if sys.platform == 'win32':
-        getters = _NODE_GETTERS_WIN32
-    else:
-        getters = _NODE_GETTERS_UNIX
-
-    for getter in getters + [_random_getnode]:
+    for getter in _NODE_GETTERS + [_random_getnode]:
         try:
             _node = getter()
         except:

Misc/NEWS.d/next/Tests/2019-04-11-07-59-43.bpo-28009.s85urF.rst

@@ -0,0 +1,3 @@
+Fix the SkipUnless logic to be based on whether a program
+is available AND can be used to get a MACADDR as basis for an UUID.
+Patch by M. Felt