import unittest from test import support import builtins import io import os import shutil import uuid def importable(name): try: __import__(name) return True except: return False class TestUUID(unittest.TestCase): last_node = None source2node = {} def test_UUID(self): equal = self.assertEqual ascending = [] for (string, curly, hex, bytes, bytes_le, fields, integer, urn, time, clock_seq, variant, version) in [ ('00000000-0000-0000-0000-000000000000', '{00000000-0000-0000-0000-000000000000}', '00000000000000000000000000000000', b'\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0', b'\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0', (0, 0, 0, 0, 0, 0), 0, 'urn:uuid:00000000-0000-0000-0000-000000000000', 0, 0, uuid.RESERVED_NCS, None), ('00010203-0405-0607-0809-0a0b0c0d0e0f', '{00010203-0405-0607-0809-0a0b0c0d0e0f}', '000102030405060708090a0b0c0d0e0f', b'\0\x01\x02\x03\x04\x05\x06\x07\x08\t\n\x0b\x0c\x0d\x0e\x0f', b'\x03\x02\x01\0\x05\x04\x07\x06\x08\t\n\x0b\x0c\x0d\x0e\x0f', (0x00010203, 0x0405, 0x0607, 8, 9, 0x0a0b0c0d0e0f), 0x000102030405060708090a0b0c0d0e0f, 'urn:uuid:00010203-0405-0607-0809-0a0b0c0d0e0f', 0x607040500010203, 0x809, uuid.RESERVED_NCS, None), ('02d9e6d5-9467-382e-8f9b-9300a64ac3cd', '{02d9e6d5-9467-382e-8f9b-9300a64ac3cd}', '02d9e6d59467382e8f9b9300a64ac3cd', b'\x02\xd9\xe6\xd5\x94\x67\x38\x2e\x8f\x9b\x93\x00\xa6\x4a\xc3\xcd', b'\xd5\xe6\xd9\x02\x67\x94\x2e\x38\x8f\x9b\x93\x00\xa6\x4a\xc3\xcd', (0x02d9e6d5, 0x9467, 0x382e, 0x8f, 0x9b, 0x9300a64ac3cd), 0x02d9e6d59467382e8f9b9300a64ac3cd, 'urn:uuid:02d9e6d5-9467-382e-8f9b-9300a64ac3cd', 0x82e946702d9e6d5, 0xf9b, uuid.RFC_4122, 3), ('12345678-1234-5678-1234-567812345678', '{12345678-1234-5678-1234-567812345678}', '12345678123456781234567812345678', b'\x12\x34\x56\x78'*4, b'\x78\x56\x34\x12\x34\x12\x78\x56\x12\x34\x56\x78\x12\x34\x56\x78', (0x12345678, 0x1234, 0x5678, 0x12, 0x34, 0x567812345678), 0x12345678123456781234567812345678, 'urn:uuid:12345678-1234-5678-1234-567812345678', 0x678123412345678, 0x1234, uuid.RESERVED_NCS, None), ('6ba7b810-9dad-11d1-80b4-00c04fd430c8', '{6ba7b810-9dad-11d1-80b4-00c04fd430c8}', '6ba7b8109dad11d180b400c04fd430c8', b'\x6b\xa7\xb8\x10\x9d\xad\x11\xd1\x80\xb4\x00\xc0\x4f\xd4\x30\xc8', b'\x10\xb8\xa7\x6b\xad\x9d\xd1\x11\x80\xb4\x00\xc0\x4f\xd4\x30\xc8', (0x6ba7b810, 0x9dad, 0x11d1, 0x80, 0xb4, 0x00c04fd430c8), 0x6ba7b8109dad11d180b400c04fd430c8, 'urn:uuid:6ba7b810-9dad-11d1-80b4-00c04fd430c8', 0x1d19dad6ba7b810, 0xb4, uuid.RFC_4122, 1), ('6ba7b811-9dad-11d1-80b4-00c04fd430c8', '{6ba7b811-9dad-11d1-80b4-00c04fd430c8}', '6ba7b8119dad11d180b400c04fd430c8', b'\x6b\xa7\xb8\x11\x9d\xad\x11\xd1\x80\xb4\x00\xc0\x4f\xd4\x30\xc8', b'\x11\xb8\xa7\x6b\xad\x9d\xd1\x11\x80\xb4\x00\xc0\x4f\xd4\x30\xc8', (0x6ba7b811, 0x9dad, 0x11d1, 0x80, 0xb4, 0x00c04fd430c8), 0x6ba7b8119dad11d180b400c04fd430c8, 'urn:uuid:6ba7b811-9dad-11d1-80b4-00c04fd430c8', 0x1d19dad6ba7b811, 0xb4, uuid.RFC_4122, 1), ('6ba7b812-9dad-11d1-80b4-00c04fd430c8', '{6ba7b812-9dad-11d1-80b4-00c04fd430c8}', '6ba7b8129dad11d180b400c04fd430c8', b'\x6b\xa7\xb8\x12\x9d\xad\x11\xd1\x80\xb4\x00\xc0\x4f\xd4\x30\xc8', b'\x12\xb8\xa7\x6b\xad\x9d\xd1\x11\x80\xb4\x00\xc0\x4f\xd4\x30\xc8', (0x6ba7b812, 0x9dad, 0x11d1, 0x80, 0xb4, 0x00c04fd430c8), 0x6ba7b8129dad11d180b400c04fd430c8, 'urn:uuid:6ba7b812-9dad-11d1-80b4-00c04fd430c8', 0x1d19dad6ba7b812, 0xb4, uuid.RFC_4122, 1), ('6ba7b814-9dad-11d1-80b4-00c04fd430c8', '{6ba7b814-9dad-11d1-80b4-00c04fd430c8}', '6ba7b8149dad11d180b400c04fd430c8', b'\x6b\xa7\xb8\x14\x9d\xad\x11\xd1\x80\xb4\x00\xc0\x4f\xd4\x30\xc8', b'\x14\xb8\xa7\x6b\xad\x9d\xd1\x11\x80\xb4\x00\xc0\x4f\xd4\x30\xc8', (0x6ba7b814, 0x9dad, 0x11d1, 0x80, 0xb4, 0x00c04fd430c8), 0x6ba7b8149dad11d180b400c04fd430c8, 'urn:uuid:6ba7b814-9dad-11d1-80b4-00c04fd430c8', 0x1d19dad6ba7b814, 0xb4, uuid.RFC_4122, 1), ('7d444840-9dc0-11d1-b245-5ffdce74fad2', '{7d444840-9dc0-11d1-b245-5ffdce74fad2}', '7d4448409dc011d1b2455ffdce74fad2', b'\x7d\x44\x48\x40\x9d\xc0\x11\xd1\xb2\x45\x5f\xfd\xce\x74\xfa\xd2', b'\x40\x48\x44\x7d\xc0\x9d\xd1\x11\xb2\x45\x5f\xfd\xce\x74\xfa\xd2', (0x7d444840, 0x9dc0, 0x11d1, 0xb2, 0x45, 0x5ffdce74fad2), 0x7d4448409dc011d1b2455ffdce74fad2, 'urn:uuid:7d444840-9dc0-11d1-b245-5ffdce74fad2', 0x1d19dc07d444840, 0x3245, uuid.RFC_4122, 1), ('e902893a-9d22-3c7e-a7b8-d6e313b71d9f', '{e902893a-9d22-3c7e-a7b8-d6e313b71d9f}', 'e902893a9d223c7ea7b8d6e313b71d9f', b'\xe9\x02\x89\x3a\x9d\x22\x3c\x7e\xa7\xb8\xd6\xe3\x13\xb7\x1d\x9f', b'\x3a\x89\x02\xe9\x22\x9d\x7e\x3c\xa7\xb8\xd6\xe3\x13\xb7\x1d\x9f', (0xe902893a, 0x9d22, 0x3c7e, 0xa7, 0xb8, 0xd6e313b71d9f), 0xe902893a9d223c7ea7b8d6e313b71d9f, 'urn:uuid:e902893a-9d22-3c7e-a7b8-d6e313b71d9f', 0xc7e9d22e902893a, 0x27b8, uuid.RFC_4122, 3), ('eb424026-6f54-4ef8-a4d0-bb658a1fc6cf', '{eb424026-6f54-4ef8-a4d0-bb658a1fc6cf}', 'eb4240266f544ef8a4d0bb658a1fc6cf', b'\xeb\x42\x40\x26\x6f\x54\x4e\xf8\xa4\xd0\xbb\x65\x8a\x1f\xc6\xcf', b'\x26\x40\x42\xeb\x54\x6f\xf8\x4e\xa4\xd0\xbb\x65\x8a\x1f\xc6\xcf', (0xeb424026, 0x6f54, 0x4ef8, 0xa4, 0xd0, 0xbb658a1fc6cf), 0xeb4240266f544ef8a4d0bb658a1fc6cf, 'urn:uuid:eb424026-6f54-4ef8-a4d0-bb658a1fc6cf', 0xef86f54eb424026, 0x24d0, uuid.RFC_4122, 4), ('f81d4fae-7dec-11d0-a765-00a0c91e6bf6', '{f81d4fae-7dec-11d0-a765-00a0c91e6bf6}', 'f81d4fae7dec11d0a76500a0c91e6bf6', b'\xf8\x1d\x4f\xae\x7d\xec\x11\xd0\xa7\x65\x00\xa0\xc9\x1e\x6b\xf6', b'\xae\x4f\x1d\xf8\xec\x7d\xd0\x11\xa7\x65\x00\xa0\xc9\x1e\x6b\xf6', (0xf81d4fae, 0x7dec, 0x11d0, 0xa7, 0x65, 0x00a0c91e6bf6), 0xf81d4fae7dec11d0a76500a0c91e6bf6, 'urn:uuid:f81d4fae-7dec-11d0-a765-00a0c91e6bf6', 0x1d07decf81d4fae, 0x2765, uuid.RFC_4122, 1), ('fffefdfc-fffe-fffe-fffe-fffefdfcfbfa', '{fffefdfc-fffe-fffe-fffe-fffefdfcfbfa}', 'fffefdfcfffefffefffefffefdfcfbfa', b'\xff\xfe\xfd\xfc\xff\xfe\xff\xfe\xff\xfe\xff\xfe\xfd\xfc\xfb\xfa', b'\xfc\xfd\xfe\xff\xfe\xff\xfe\xff\xff\xfe\xff\xfe\xfd\xfc\xfb\xfa', (0xfffefdfc, 0xfffe, 0xfffe, 0xff, 0xfe, 0xfffefdfcfbfa), 0xfffefdfcfffefffefffefffefdfcfbfa, 'urn:uuid:fffefdfc-fffe-fffe-fffe-fffefdfcfbfa', 0xffefffefffefdfc, 0x3ffe, uuid.RESERVED_FUTURE, None), ('ffffffff-ffff-ffff-ffff-ffffffffffff', '{ffffffff-ffff-ffff-ffff-ffffffffffff}', 'ffffffffffffffffffffffffffffffff', b'\xff'*16, b'\xff'*16, (0xffffffff, 0xffff, 0xffff, 0xff, 0xff, 0xffffffffffff), 0xffffffffffffffffffffffffffffffff, 'urn:uuid:ffffffff-ffff-ffff-ffff-ffffffffffff', 0xfffffffffffffff, 0x3fff, uuid.RESERVED_FUTURE, None), ]: equivalents = [] # Construct each UUID in several different ways. for u in [uuid.UUID(string), uuid.UUID(curly), uuid.UUID(hex), uuid.UUID(bytes=bytes), uuid.UUID(bytes_le=bytes_le), uuid.UUID(fields=fields), uuid.UUID(int=integer), uuid.UUID(urn)]: # Test all conversions and properties of the UUID object. equal(str(u), string) equal(int(u), integer) equal(u.bytes, bytes) equal(u.bytes_le, bytes_le) equal(u.fields, fields) equal(u.time_low, fields[0]) equal(u.time_mid, fields[1]) equal(u.time_hi_version, fields[2]) equal(u.clock_seq_hi_variant, fields[3]) equal(u.clock_seq_low, fields[4]) equal(u.node, fields[5]) equal(u.hex, hex) equal(u.int, integer) equal(u.urn, urn) equal(u.time, time) equal(u.clock_seq, clock_seq) equal(u.variant, variant) equal(u.version, version) equivalents.append(u) # Different construction methods should give the same UUID. for u in equivalents: for v in equivalents: equal(u, v) # Bug 7380: "bytes" and "bytes_le" should give the same type. equal(type(u.bytes), builtins.bytes) equal(type(u.bytes_le), builtins.bytes) ascending.append(u) # Test comparison of UUIDs. for i in range(len(ascending)): for j in range(len(ascending)): equal(i < j, ascending[i] < ascending[j]) equal(i <= j, ascending[i] <= ascending[j]) equal(i == j, ascending[i] == ascending[j]) equal(i > j, ascending[i] > ascending[j]) equal(i >= j, ascending[i] >= ascending[j]) equal(i != j, ascending[i] != ascending[j]) # Test sorting of UUIDs (above list is in ascending order). resorted = ascending[:] resorted.reverse() resorted.sort() equal(ascending, resorted) def test_exceptions(self): badvalue = lambda f: self.assertRaises(ValueError, f) badtype = lambda f: self.assertRaises(TypeError, f) # Badly formed hex strings. badvalue(lambda: uuid.UUID('')) badvalue(lambda: uuid.UUID('abc')) badvalue(lambda: uuid.UUID('1234567812345678123456781234567')) badvalue(lambda: uuid.UUID('123456781234567812345678123456789')) badvalue(lambda: uuid.UUID('123456781234567812345678z2345678')) # Badly formed bytes. badvalue(lambda: uuid.UUID(bytes='abc')) badvalue(lambda: uuid.UUID(bytes='\0'*15)) badvalue(lambda: uuid.UUID(bytes='\0'*17)) # Badly formed bytes_le. badvalue(lambda: uuid.UUID(bytes_le='abc')) badvalue(lambda: uuid.UUID(bytes_le='\0'*15)) badvalue(lambda: uuid.UUID(bytes_le='\0'*17)) # Badly formed fields. badvalue(lambda: uuid.UUID(fields=(1,))) badvalue(lambda: uuid.UUID(fields=(1, 2, 3, 4, 5))) badvalue(lambda: uuid.UUID(fields=(1, 2, 3, 4, 5, 6, 7))) # Field values out of range. badvalue(lambda: uuid.UUID(fields=(-1, 0, 0, 0, 0, 0))) badvalue(lambda: uuid.UUID(fields=(0x100000000, 0, 0, 0, 0, 0))) badvalue(lambda: uuid.UUID(fields=(0, -1, 0, 0, 0, 0))) badvalue(lambda: uuid.UUID(fields=(0, 0x10000, 0, 0, 0, 0))) badvalue(lambda: uuid.UUID(fields=(0, 0, -1, 0, 0, 0))) badvalue(lambda: uuid.UUID(fields=(0, 0, 0x10000, 0, 0, 0))) badvalue(lambda: uuid.UUID(fields=(0, 0, 0, -1, 0, 0))) badvalue(lambda: uuid.UUID(fields=(0, 0, 0, 0x100, 0, 0))) badvalue(lambda: uuid.UUID(fields=(0, 0, 0, 0, -1, 0))) badvalue(lambda: uuid.UUID(fields=(0, 0, 0, 0, 0x100, 0))) badvalue(lambda: uuid.UUID(fields=(0, 0, 0, 0, 0, -1))) badvalue(lambda: uuid.UUID(fields=(0, 0, 0, 0, 0, 0x1000000000000))) # Version number out of range. badvalue(lambda: uuid.UUID('00'*16, version=0)) badvalue(lambda: uuid.UUID('00'*16, version=6)) # Integer value out of range. badvalue(lambda: uuid.UUID(int=-1)) badvalue(lambda: uuid.UUID(int=1<<128)) # Must supply exactly one of hex, bytes, fields, int. h, b, f, i = '00'*16, b'\0'*16, (0, 0, 0, 0, 0, 0), 0 uuid.UUID(h) uuid.UUID(hex=h) uuid.UUID(bytes=b) uuid.UUID(bytes_le=b) uuid.UUID(fields=f) uuid.UUID(int=i) # Wrong number of arguments (positional). badtype(lambda: uuid.UUID()) badtype(lambda: uuid.UUID(h, b)) badtype(lambda: uuid.UUID(h, b, b)) badtype(lambda: uuid.UUID(h, b, b, f)) badtype(lambda: uuid.UUID(h, b, b, f, i)) # Duplicate arguments. for hh in [[], [('hex', h)]]: for bb in [[], [('bytes', b)]]: for bble in [[], [('bytes_le', b)]]: for ii in [[], [('int', i)]]: for ff in [[], [('fields', f)]]: args = dict(hh + bb + bble + ii + ff) if len(args) != 0: badtype(lambda: uuid.UUID(h, **args)) if len(args) != 1: badtype(lambda: uuid.UUID(**args)) # Immutability. u = uuid.UUID(h) badtype(lambda: setattr(u, 'hex', h)) badtype(lambda: setattr(u, 'bytes', b)) badtype(lambda: setattr(u, 'bytes_le', b)) badtype(lambda: setattr(u, 'fields', f)) badtype(lambda: setattr(u, 'int', i)) badtype(lambda: setattr(u, 'time_low', 0)) badtype(lambda: setattr(u, 'time_mid', 0)) badtype(lambda: setattr(u, 'time_hi_version', 0)) badtype(lambda: setattr(u, 'time_hi_version', 0)) badtype(lambda: setattr(u, 'clock_seq_hi_variant', 0)) badtype(lambda: setattr(u, 'clock_seq_low', 0)) badtype(lambda: setattr(u, 'node', 0)) def check_node(self, node, source): message = "%012x is not an RFC 4122 node ID" % node self.assertTrue(0 < node, message) self.assertTrue(node < (1 << 48), message) TestUUID.source2node[source] = node if TestUUID.last_node: if TestUUID.last_node != node: msg = "different sources disagree on node:\n" for s, n in TestUUID.source2node.items(): msg += " from source %r, node was %012x\n" % (s, n) # There's actually no reason to expect the MAC addresses # to agree across various methods -- e.g., a box may have # multiple network interfaces, and different ways of getting # a MAC address may favor different HW. ##self.fail(msg) else: TestUUID.last_node = node @unittest.skipUnless(os.name == 'posix', 'requires Posix') def test_ifconfig_getnode(self): node = uuid._ifconfig_getnode() if node is not None: self.check_node(node, 'ifconfig') @unittest.skipUnless(os.name == 'nt', 'requires Windows') def test_ipconfig_getnode(self): node = uuid._ipconfig_getnode() if node is not None: self.check_node(node, 'ipconfig') @unittest.skipUnless(importable('win32wnet'), 'requires win32wnet') @unittest.skipUnless(importable('netbios'), 'requires netbios') def test_netbios_getnode(self): self.check_node(uuid._netbios_getnode(), 'netbios') def test_random_getnode(self): node = uuid._random_getnode() # Least significant bit of first octet must be set. self.assertTrue(node & 0x010000000000) self.assertTrue(node < (1 << 48)) @unittest.skipUnless(os.name == 'posix', 'requires Posix') @unittest.skipUnless(importable('ctypes'), 'requires ctypes') def test_unixdll_getnode(self): try: # Issues 1481, 3581: _uuid_generate_time() might be None. self.check_node(uuid._unixdll_getnode(), 'unixdll') except TypeError: pass @unittest.skipUnless(os.name == 'nt', 'requires Windows') @unittest.skipUnless(importable('ctypes'), 'requires ctypes') def test_windll_getnode(self): self.check_node(uuid._windll_getnode(), 'windll') def test_getnode(self): node1 = uuid.getnode() self.check_node(node1, "getnode1") # Test it again to ensure consistency. node2 = uuid.getnode() self.check_node(node2, "getnode2") self.assertEqual(node1, node2) @unittest.skipUnless(os.name == 'posix', 'requires Posix') def test_find_mac(self): data = '''\ fake hwaddr cscotun0 Link encap:UNSPEC HWaddr 00-00-00-00-00-00-00-00-00-00-00-00-00-00-00-00 eth0 Link encap:Ethernet HWaddr 12:34:56:78:90:ab ''' def mock_popen(cmd): return io.StringIO(data) if shutil.which('ifconfig') is None: path = os.pathsep.join(('/sbin', '/usr/sbin')) if shutil.which('ifconfig', path=path) is None: self.skipTest('requires ifconfig') with support.swap_attr(os, 'popen', mock_popen): mac = uuid._find_mac( command='ifconfig', args='', hw_identifiers=['hwaddr'], get_index=lambda x: x + 1, ) self.assertEqual(mac, 0x1234567890ab) @unittest.skipUnless(importable('ctypes'), 'requires ctypes') def test_uuid1(self): equal = self.assertEqual # Make sure uuid1() generates UUIDs that are actually version 1. for u in [uuid.uuid1() for i in range(10)]: equal(u.variant, uuid.RFC_4122) equal(u.version, 1) # Make sure the generated UUIDs are actually unique. uuids = {} for u in [uuid.uuid1() for i in range(1000)]: uuids[u] = 1 equal(len(uuids.keys()), 1000) # Make sure the supplied node ID appears in the UUID. u = uuid.uuid1(0) equal(u.node, 0) u = uuid.uuid1(0x123456789abc) equal(u.node, 0x123456789abc) u = uuid.uuid1(0xffffffffffff) equal(u.node, 0xffffffffffff) # Make sure the supplied clock sequence appears in the UUID. u = uuid.uuid1(0x123456789abc, 0) equal(u.node, 0x123456789abc) equal(((u.clock_seq_hi_variant & 0x3f) << 8) | u.clock_seq_low, 0) u = uuid.uuid1(0x123456789abc, 0x1234) equal(u.node, 0x123456789abc) equal(((u.clock_seq_hi_variant & 0x3f) << 8) | u.clock_seq_low, 0x1234) u = uuid.uuid1(0x123456789abc, 0x3fff) equal(u.node, 0x123456789abc) equal(((u.clock_seq_hi_variant & 0x3f) << 8) | u.clock_seq_low, 0x3fff) def test_uuid3(self): equal = self.assertEqual # Test some known version-3 UUIDs. for u, v in [(uuid.uuid3(uuid.NAMESPACE_DNS, 'python.org'), '6fa459ea-ee8a-3ca4-894e-db77e160355e'), (uuid.uuid3(uuid.NAMESPACE_URL, 'http://python.org/'), '9fe8e8c4-aaa8-32a9-a55c-4535a88b748d'), (uuid.uuid3(uuid.NAMESPACE_OID, '1.3.6.1'), 'dd1a1cef-13d5-368a-ad82-eca71acd4cd1'), (uuid.uuid3(uuid.NAMESPACE_X500, 'c=ca'), '658d3002-db6b-3040-a1d1-8ddd7d189a4d'), ]: equal(u.variant, uuid.RFC_4122) equal(u.version, 3) equal(u, uuid.UUID(v)) equal(str(u), v) @unittest.skipUnless(importable('ctypes'), 'requires ctypes') def test_uuid4(self): equal = self.assertEqual # Make sure uuid4() generates UUIDs that are actually version 4. for u in [uuid.uuid4() for i in range(10)]: equal(u.variant, uuid.RFC_4122) equal(u.version, 4) # Make sure the generated UUIDs are actually unique. uuids = {} for u in [uuid.uuid4() for i in range(1000)]: uuids[u] = 1 equal(len(uuids.keys()), 1000) def test_uuid5(self): equal = self.assertEqual # Test some known version-5 UUIDs. for u, v in [(uuid.uuid5(uuid.NAMESPACE_DNS, 'python.org'), '886313e1-3b8a-5372-9b90-0c9aee199e5d'), (uuid.uuid5(uuid.NAMESPACE_URL, 'http://python.org/'), '4c565f0d-3f5a-5890-b41b-20cf47701c5e'), (uuid.uuid5(uuid.NAMESPACE_OID, '1.3.6.1'), '1447fa61-5277-5fef-a9b3-fbc6e44f4af3'), (uuid.uuid5(uuid.NAMESPACE_X500, 'c=ca'), 'cc957dd1-a972-5349-98cd-874190002798'), ]: equal(u.variant, uuid.RFC_4122) equal(u.version, 5) equal(u, uuid.UUID(v)) equal(str(u), v) @unittest.skipUnless(os.name == 'posix', 'requires Posix') def testIssue8621(self): # On at least some versions of OSX uuid.uuid4 generates # the same sequence of UUIDs in the parent and any # children started using fork. fds = os.pipe() pid = os.fork() if pid == 0: os.close(fds[0]) value = uuid.uuid4() os.write(fds[1], value.hex.encode('latin-1')) os._exit(0) else: os.close(fds[1]) self.addCleanup(os.close, fds[0]) parent_value = uuid.uuid4().hex os.waitpid(pid, 0) child_value = os.read(fds[0], 100).decode('latin-1') self.assertNotEqual(parent_value, child_value) if __name__ == '__main__': unittest.main()