diff --git a/Lib/test/test_argparse.py b/Lib/test/test_argparse.py
index 03c95fa..8d80336 100644
--- a/Lib/test/test_argparse.py
+++ b/Lib/test/test_argparse.py
@@ -4328,7 +4328,7 @@
     def _test_module_encoding(self, path):
         path, _ = os.path.splitext(path)
         path += ".py"
-        with codecs.open(path, 'r', 'utf8') as f:
+        with codecs.open(path, 'r', 'utf-8') as f:
             f.read()
 
     def test_argparse_module_encoding(self):
diff --git a/Lib/test/test_bigmem.py b/Lib/test/test_bigmem.py
index ac6b109..f9a0a3d 100644
--- a/Lib/test/test_bigmem.py
+++ b/Lib/test/test_bigmem.py
@@ -707,7 +707,7 @@
 class BytesTest(unittest.TestCase, BaseStrTest):
 
     def from_latin1(self, s):
-        return s.encode("latin1")
+        return s.encode("latin-1")
 
     @bigmemtest(minsize=_2G + 2, memuse=1 + character_size)
     def test_decode(self, size):
@@ -718,7 +718,7 @@
 class BytearrayTest(unittest.TestCase, BaseStrTest):
 
     def from_latin1(self, s):
-        return bytearray(s.encode("latin1"))
+        return bytearray(s.encode("latin-1"))
 
     @bigmemtest(minsize=_2G + 2, memuse=1 + character_size)
     def test_decode(self, size):
diff --git a/Lib/test/test_bytes.py b/Lib/test/test_bytes.py
index e5c7ccd..84867bb 100644
--- a/Lib/test/test_bytes.py
+++ b/Lib/test/test_bytes.py
@@ -188,24 +188,26 @@
 
     def test_encoding(self):
         sample = "Hello world\n\u1234\u5678\u9abc"
-        for enc in ("utf8", "utf16"):
+        for enc in ("utf-8", "utf-16"):
             b = self.type2test(sample, enc)
             self.assertEqual(b, self.type2test(sample.encode(enc)))
-        self.assertRaises(UnicodeEncodeError, self.type2test, sample, "latin1")
-        b = self.type2test(sample, "latin1", "ignore")
+        self.assertRaises(UnicodeEncodeError, self.type2test, sample, "latin-1")
+        b = self.type2test(sample, "latin-1", "ignore")
         self.assertEqual(b, self.type2test(sample[:-3], "utf-8"))
 
     def test_decode(self):
         sample = "Hello world\n\u1234\u5678\u9abc\def0\def0"
-        for enc in ("utf8", "utf16"):
+        for enc in ("utf-8", "utf-16"):
             b = self.type2test(sample, enc)
             self.assertEqual(b.decode(enc), sample)
         sample = "Hello world\n\x80\x81\xfe\xff"
-        b = self.type2test(sample, "latin1")
-        self.assertRaises(UnicodeDecodeError, b.decode, "utf8")
-        self.assertEqual(b.decode("utf8", "ignore"), "Hello world\n")
-        self.assertEqual(b.decode(errors="ignore", encoding="utf8"),
+        b = self.type2test(sample, "latin-1")
+        self.assertRaises(UnicodeDecodeError, b.decode, "utf-8")
+        self.assertEqual(b.decode("utf-8", "ignore"), "Hello world\n")
+        self.assertEqual(b.decode(errors="ignore", encoding="utf-8"),
                          "Hello world\n")
+        # Default encoding is utf-8
+        self.assertEqual(self.type2test(b'\xe2\x98\x83').decode(), '\u2603')
 
     def test_from_int(self):
         b = self.type2test(0)
diff --git a/Lib/test/test_cmd_line.py b/Lib/test/test_cmd_line.py
index c4e3adf..a0a85ae 100644
--- a/Lib/test/test_cmd_line.py
+++ b/Lib/test/test_cmd_line.py
@@ -151,7 +151,7 @@
     @unittest.skipUnless(sys.platform == 'darwin', 'test specific to Mac OS X')
     def test_osx_utf8(self):
         def check_output(text):
-            decoded = text.decode('utf8', 'surrogateescape')
+            decoded = text.decode('utf-8', 'surrogateescape')
             expected = ascii(decoded).encode('ascii') + b'\n'
 
             env = os.environ.copy()
@@ -223,7 +223,7 @@
         self.assertIn(path2.encode('ascii'), out)
 
     def test_displayhook_unencodable(self):
-        for encoding in ('ascii', 'latin1', 'utf8'):
+        for encoding in ('ascii', 'latin-1', 'utf-8'):
             env = os.environ.copy()
             env['PYTHONIOENCODING'] = encoding
             p = subprocess.Popen(
diff --git a/Lib/test/test_codecs.py b/Lib/test/test_codecs.py
index d560d7a..67a5aed 100644
--- a/Lib/test/test_codecs.py
+++ b/Lib/test/test_codecs.py
@@ -1250,7 +1250,7 @@
         self.assertEqual(ef.read(), b'\\\xd5\n\x00\x00\xae')
 
         f = io.BytesIO()
-        ef = codecs.EncodedFile(f, 'utf-8', 'latin1')
+        ef = codecs.EncodedFile(f, 'utf-8', 'latin-1')
         ef.write(b'\xc3\xbc')
         self.assertEqual(f.getvalue(), b'\xfc')
 
@@ -1611,7 +1611,7 @@
 
     def test_latin1(self):
         # Issue6373
-        self.assertEqual("\udce4\udceb\udcef\udcf6\udcfc".encode("latin1", "surrogateescape"),
+        self.assertEqual("\udce4\udceb\udcef\udcf6\udcfc".encode("latin-1", "surrogateescape"),
                          b"\xe4\xeb\xef\xf6\xfc")
 
 
diff --git a/Lib/test/test_io.py b/Lib/test/test_io.py
index 3a2589e..624a68d 100644
--- a/Lib/test/test_io.py
+++ b/Lib/test/test_io.py
@@ -46,7 +46,7 @@
 
 def _default_chunk_size():
     """Get the default TextIOWrapper chunk size"""
-    with open(__file__, "r", encoding="latin1") as f:
+    with open(__file__, "r", encoding="latin-1") as f:
         return f._CHUNK_SIZE
 
 
@@ -1684,11 +1684,11 @@
         r = self.BytesIO(b"\xc3\xa9\n\n")
         b = self.BufferedReader(r, 1000)
         t = self.TextIOWrapper(b)
-        t.__init__(b, encoding="latin1", newline="\r\n")
-        self.assertEqual(t.encoding, "latin1")
+        t.__init__(b, encoding="latin-1", newline="\r\n")
+        self.assertEqual(t.encoding, "latin-1")
         self.assertEqual(t.line_buffering, False)
-        t.__init__(b, encoding="utf8", line_buffering=True)
-        self.assertEqual(t.encoding, "utf8")
+        t.__init__(b, encoding="utf-8", line_buffering=True)
+        self.assertEqual(t.encoding, "utf-8")
         self.assertEqual(t.line_buffering, True)
         self.assertEqual("\xe9\n", t.readline())
         self.assertRaises(TypeError, t.__init__, b, newline=42)
@@ -1738,8 +1738,8 @@
     def test_encoding(self):
         # Check the encoding attribute is always set, and valid
         b = self.BytesIO()
-        t = self.TextIOWrapper(b, encoding="utf8")
-        self.assertEqual(t.encoding, "utf8")
+        t = self.TextIOWrapper(b, encoding="utf-8")
+        self.assertEqual(t.encoding, "utf-8")
         t = self.TextIOWrapper(b)
         self.assertTrue(t.encoding is not None)
         codecs.lookup(t.encoding)
@@ -1918,7 +1918,7 @@
 
     def test_basic_io(self):
         for chunksize in (1, 2, 3, 4, 5, 15, 16, 17, 31, 32, 33, 63, 64, 65):
-            for enc in "ascii", "latin1", "utf8" :# , "utf-16-be", "utf-16-le":
+            for enc in "ascii", "latin-1", "utf-8" :# , "utf-16-be", "utf-16-le":
                 f = self.open(support.TESTFN, "w+", encoding=enc)
                 f._CHUNK_SIZE = chunksize
                 self.assertEqual(f.write("abc"), 3)
@@ -1968,7 +1968,7 @@
         self.assertEqual(rlines, wlines)
 
     def test_telling(self):
-        f = self.open(support.TESTFN, "w+", encoding="utf8")
+        f = self.open(support.TESTFN, "w+", encoding="utf-8")
         p0 = f.tell()
         f.write("\xff\n")
         p1 = f.tell()
diff --git a/Lib/test/test_mailbox.py b/Lib/test/test_mailbox.py
index 1e4f887..03f814a 100644
--- a/Lib/test/test_mailbox.py
+++ b/Lib/test/test_mailbox.py
@@ -95,14 +95,14 @@
             """)
 
     def test_add_invalid_8bit_bytes_header(self):
-        key = self._box.add(self._nonascii_msg.encode('latin1'))
+        key = self._box.add(self._nonascii_msg.encode('latin-1'))
         self.assertEqual(len(self._box), 1)
         self.assertEqual(self._box.get_bytes(key),
-            self._nonascii_msg.encode('latin1'))
+            self._nonascii_msg.encode('latin-1'))
 
     def test_invalid_nonascii_header_as_string(self):
         subj = self._nonascii_msg.splitlines()[1]
-        key = self._box.add(subj.encode('latin1'))
+        key = self._box.add(subj.encode('latin-1'))
         self.assertEqual(self._box.get_string(key),
             'Subject: =?unknown-8bit?b?RmFsaW5hcHThciBo4Xpob3pzeuFsbO104XNz'
             'YWwuIE3hciByZW5kZWx06Ww/?=\n\n')
diff --git a/Lib/test/test_nntplib.py b/Lib/test/test_nntplib.py
index 4577ddb..e463e52 100644
--- a/Lib/test/test_nntplib.py
+++ b/Lib/test/test_nntplib.py
@@ -813,7 +813,7 @@
 
     def _check_article_body(self, lines):
         self.assertEqual(len(lines), 4)
-        self.assertEqual(lines[-1].decode('utf8'), "-- Signed by André.")
+        self.assertEqual(lines[-1].decode('utf-8'), "-- Signed by André.")
         self.assertEqual(lines[-2], b"")
         self.assertEqual(lines[-3], b".Here is a dot-starting line.")
         self.assertEqual(lines[-4], b"This is just a test article.")
diff --git a/Lib/test/test_pep3120.py b/Lib/test/test_pep3120.py
index 09fedf0..496f8da 100644
--- a/Lib/test/test_pep3120.py
+++ b/Lib/test/test_pep3120.py
@@ -19,8 +19,8 @@
         try:
             import test.badsyntax_pep3120
         except SyntaxError as msg:
-            msg = str(msg)
-            self.assertTrue('UTF-8' in msg or 'utf8' in msg)
+            msg = str(msg).lower()
+            self.assertTrue('utf-8' in msg or 'utf8' in msg)
         else:
             self.fail("expected exception didn't occur")
 
diff --git a/Lib/test/test_sax.py b/Lib/test/test_sax.py
index 0f6a1ca..bddb375 100644
--- a/Lib/test/test_sax.py
+++ b/Lib/test/test_sax.py
@@ -20,8 +20,8 @@
 TEST_XMLFILE = findfile("test.xml", subdir="xmltestdata")
 TEST_XMLFILE_OUT = findfile("test.xml.out", subdir="xmltestdata")
 try:
-    TEST_XMLFILE.encode("utf8")
-    TEST_XMLFILE_OUT.encode("utf8")
+    TEST_XMLFILE.encode("utf-8")
+    TEST_XMLFILE_OUT.encode("utf-8")
 except UnicodeEncodeError:
     raise unittest.SkipTest("filename is not encodable to utf8")
 
diff --git a/Lib/test/test_shelve.py b/Lib/test/test_shelve.py
index c9c0067..13c1265 100644
--- a/Lib/test/test_shelve.py
+++ b/Lib/test/test_shelve.py
@@ -129,8 +129,8 @@
         shelve.Shelf(d)[key] = [1]
         self.assertIn(key.encode('utf-8'), d)
         # but a different one can be given
-        shelve.Shelf(d, keyencoding='latin1')[key] = [1]
-        self.assertIn(key.encode('latin1'), d)
+        shelve.Shelf(d, keyencoding='latin-1')[key] = [1]
+        self.assertIn(key.encode('latin-1'), d)
         # with all consequences
         s = shelve.Shelf(d, keyencoding='ascii')
         self.assertRaises(UnicodeEncodeError, s.__setitem__, key, [1])
diff --git a/Lib/test/test_socket.py b/Lib/test/test_socket.py
index 23d22a8..9d5d8ca 100644
--- a/Lib/test/test_socket.py
+++ b/Lib/test/test_socket.py
@@ -44,7 +44,7 @@
         return 0, 0, 0
 
 HOST = support.HOST
-MSG = 'Michael Gilfix was here\u1234\r\n'.encode('utf8') ## test unicode string and carriage return
+MSG = 'Michael Gilfix was here\u1234\r\n'.encode('utf-8') ## test unicode string and carriage return
 SUPPORTS_IPV6 = socket.has_ipv6 and try_address('::1', family=socket.AF_INET6)
 
 try:
@@ -1065,7 +1065,7 @@
     """
 
     bufsize = -1 # Use default buffer size
-    encoding = 'utf8'
+    encoding = 'utf-8'
     errors = 'strict'
     newline = None
 
@@ -1269,7 +1269,7 @@
             data = b''
         else:
             data = ''
-            expecting = expecting.decode('utf8')
+            expecting = expecting.decode('utf-8')
         while len(data) != len(expecting):
             part = fo.read(size)
             if not part:
@@ -1427,7 +1427,7 @@
     """Tests for socket.makefile() in text mode (rather than binary)"""
 
     read_mode = 'r'
-    read_msg = MSG.decode('utf8')
+    read_msg = MSG.decode('utf-8')
     write_mode = 'wb'
     write_msg = MSG
     newline = ''
@@ -1439,7 +1439,7 @@
     read_mode = 'rb'
     read_msg = MSG
     write_mode = 'w'
-    write_msg = MSG.decode('utf8')
+    write_msg = MSG.decode('utf-8')
     newline = ''
 
 
@@ -1447,9 +1447,9 @@
     """Tests for socket.makefile() in text mode (rather than binary)"""
 
     read_mode = 'r'
-    read_msg = MSG.decode('utf8')
+    read_msg = MSG.decode('utf-8')
     write_mode = 'w'
-    write_msg = MSG.decode('utf8')
+    write_msg = MSG.decode('utf-8')
     newline = ''
 
 
diff --git a/Lib/test/test_strlit.py b/Lib/test/test_strlit.py
index 23d96f8..2bcf4d1 100644
--- a/Lib/test/test_strlit.py
+++ b/Lib/test/test_strlit.py
@@ -130,7 +130,7 @@
         self.assertRaises(SyntaxError, self.check_encoding, "utf-8", extra)
 
     def test_file_utf8(self):
-        self.check_encoding("utf8")
+        self.check_encoding("utf-8")
 
     def test_file_iso_8859_1(self):
         self.check_encoding("iso-8859-1")
diff --git a/Lib/test/test_subprocess.py b/Lib/test/test_subprocess.py
index 4b58308..9e267eb 100644
--- a/Lib/test/test_subprocess.py
+++ b/Lib/test/test_subprocess.py
@@ -1191,7 +1191,7 @@
         stdout, stderr = p.communicate()
         self.assertEqual(0, p.returncode, "sigchild_ignore.py exited"
                          " non-zero with this error:\n%s" %
-                         stderr.decode('utf8'))
+                         stderr.decode('utf-8'))
 
 
 @unittest.skipUnless(mswindows, "Windows specific tests")
diff --git a/Lib/test/test_tarfile.py b/Lib/test/test_tarfile.py
index 68e094d..a645bf2 100644
--- a/Lib/test/test_tarfile.py
+++ b/Lib/test/test_tarfile.py
@@ -1289,7 +1289,7 @@
         self._test_unicode_filename("utf7")
 
     def test_utf8_filename(self):
-        self._test_unicode_filename("utf8")
+        self._test_unicode_filename("utf-8")
 
     def _test_unicode_filename(self, encoding):
         tar = tarfile.open(tmpname, "w", format=self.format, encoding=encoding, errors="strict")
@@ -1368,7 +1368,7 @@
     def test_bad_pax_header(self):
         # Test for issue #8633. GNU tar <= 1.23 creates raw binary fields
         # without a hdrcharset=BINARY header.
-        for encoding, name in (("utf8", "pax/bad-pax-\udce4\udcf6\udcfc"),
+        for encoding, name in (("utf-8", "pax/bad-pax-\udce4\udcf6\udcfc"),
                 ("iso8859-1", "pax/bad-pax-\xe4\xf6\xfc"),):
             with tarfile.open(tarname, encoding=encoding, errors="surrogateescape") as tar:
                 try:
@@ -1383,7 +1383,7 @@
 
     def test_binary_header(self):
         # Test a POSIX.1-2008 compatible header with a hdrcharset=BINARY field.
-        for encoding, name in (("utf8", "pax/hdrcharset-\udce4\udcf6\udcfc"),
+        for encoding, name in (("utf-8", "pax/hdrcharset-\udce4\udcf6\udcfc"),
                 ("iso8859-1", "pax/hdrcharset-\xe4\xf6\xfc"),):
             with tarfile.open(tarname, encoding=encoding, errors="surrogateescape") as tar:
                 try:
diff --git a/Lib/test/test_unicode.py b/Lib/test/test_unicode.py
index 9ad9eed..d97894c 100644
--- a/Lib/test/test_unicode.py
+++ b/Lib/test/test_unicode.py
@@ -1182,11 +1182,14 @@
         self.assertEqual('hello'.encode('ascii'), b'hello')
         self.assertEqual('hello'.encode('utf-7'), b'hello')
         self.assertEqual('hello'.encode('utf-8'), b'hello')
-        self.assertEqual('hello'.encode('utf8'), b'hello')
+        self.assertEqual('hello'.encode('utf-8'), b'hello')
         self.assertEqual('hello'.encode('utf-16-le'), b'h\000e\000l\000l\000o\000')
         self.assertEqual('hello'.encode('utf-16-be'), b'\000h\000e\000l\000l\000o')
         self.assertEqual('hello'.encode('latin-1'), b'hello')
 
+        # Default encoding is utf-8
+        self.assertEqual('\u2603'.encode(), b'\xe2\x98\x83')
+
         # Roundtrip safety for BMP (just the first 1024 chars)
         for c in range(1024):
             u = chr(c)
diff --git a/Lib/test/test_urllib.py b/Lib/test/test_urllib.py
index 3003331..e148c62 100644
--- a/Lib/test/test_urllib.py
+++ b/Lib/test/test_urllib.py
@@ -251,7 +251,7 @@
     def constructLocalFileUrl(self, filePath):
         filePath = os.path.abspath(filePath)
         try:
-            filePath.encode("utf8")
+            filePath.encode("utf-8")
         except UnicodeEncodeError:
             raise unittest.SkipTest("filePath is not encodable to utf8")
         return "file://%s" % urllib.request.pathname2url(filePath)
diff --git a/Lib/test/test_urllib2.py b/Lib/test/test_urllib2.py
index 1433670..4ddbe3f 100644
--- a/Lib/test/test_urllib2.py
+++ b/Lib/test/test_urllib2.py
@@ -599,7 +599,7 @@
 
 def sanepathname2url(path):
     try:
-        path.encode("utf8")
+        path.encode("utf-8")
     except UnicodeEncodeError:
         raise unittest.SkipTest("path is not encodable to utf8")
     urlpath = urllib.request.pathname2url(path)
diff --git a/Lib/test/test_uuid.py b/Lib/test/test_uuid.py
index 43fa656..7bc59ed 100644
--- a/Lib/test/test_uuid.py
+++ b/Lib/test/test_uuid.py
@@ -471,14 +471,14 @@
         if pid == 0:
             os.close(fds[0])
             value = uuid.uuid4()
-            os.write(fds[1], value.hex.encode('latin1'))
+            os.write(fds[1], value.hex.encode('latin-1'))
             os._exit(0)
 
         else:
             os.close(fds[1])
             parent_value = uuid.uuid4().hex
             os.waitpid(pid, 0)
-            child_value = os.read(fds[0], 100).decode('latin1')
+            child_value = os.read(fds[0], 100).decode('latin-1')
 
             self.assertNotEqual(parent_value, child_value)
 
diff --git a/Lib/test/test_xml_etree.py b/Lib/test/test_xml_etree.py
index 22fafa9..40c2291 100644
--- a/Lib/test/test_xml_etree.py
+++ b/Lib/test/test_xml_etree.py
@@ -22,7 +22,7 @@
 
 SIMPLE_XMLFILE = findfile("simple.xml", subdir="xmltestdata")
 try:
-    SIMPLE_XMLFILE.encode("utf8")
+    SIMPLE_XMLFILE.encode("utf-8")
 except UnicodeEncodeError:
     raise unittest.SkipTest("filename is not encodable to utf8")
 SIMPLE_NS_XMLFILE = findfile("simple-ns.xml", subdir="xmltestdata")
@@ -1255,8 +1255,8 @@
 
     >>> ET.tostring(ET.PI('test', '<testing&>'))
     b'<?test <testing&>?>'
-    >>> ET.tostring(ET.PI('test', '<testing&>\xe3'), 'latin1')
-    b"<?xml version='1.0' encoding='latin1'?>\\n<?test <testing&>\\xe3?>"
+    >>> ET.tostring(ET.PI('test', '<testing&>\xe3'), 'latin-1')
+    b"<?xml version='1.0' encoding='latin-1'?>\\n<?test <testing&>\\xe3?>"
     """
 
 #