diff --git a/Lib/test/test_array.py b/Lib/test/test_array.py
index d8d4ea7..d7b4fa8 100755
--- a/Lib/test/test_array.py
+++ b/Lib/test/test_array.py
@@ -11,6 +11,7 @@
 import io
 import math
 import struct
+import warnings
 
 import array
 from array import _array_reconstructor as array_reconstructor
@@ -367,15 +368,35 @@
         self.assertEqual(a, b)
 
     def test_tofromstring(self):
+        nb_warnings = 4
+        with warnings.catch_warnings(record=True) as r:
+            warnings.filterwarnings("always",
+                                    message=r"(to|from)string\(\) is deprecated",
+                                    category=DeprecationWarning)
+            a = array.array(self.typecode, 2*self.example)
+            b = array.array(self.typecode)
+            self.assertRaises(TypeError, a.tostring, 42)
+            self.assertRaises(TypeError, b.fromstring)
+            self.assertRaises(TypeError, b.fromstring, 42)
+            b.fromstring(a.tostring())
+            self.assertEqual(a, b)
+            if a.itemsize>1:
+                self.assertRaises(ValueError, b.fromstring, "x")
+                nb_warnings += 1
+        self.assertEqual(len(r), nb_warnings)
+
+    def test_tofrombytes(self):
         a = array.array(self.typecode, 2*self.example)
         b = array.array(self.typecode)
-        self.assertRaises(TypeError, a.tostring, 42)
-        self.assertRaises(TypeError, b.fromstring)
-        self.assertRaises(TypeError, b.fromstring, 42)
-        b.fromstring(a.tostring())
+        self.assertRaises(TypeError, a.tobytes, 42)
+        self.assertRaises(TypeError, b.frombytes)
+        self.assertRaises(TypeError, b.frombytes, 42)
+        b.frombytes(a.tobytes())
+        c = array.array(self.typecode, bytearray(a.tobytes()))
         self.assertEqual(a, b)
+        self.assertEqual(a, c)
         if a.itemsize>1:
-            self.assertRaises(ValueError, b.fromstring, "x")
+            self.assertRaises(ValueError, b.frombytes, b"x")
 
     def test_repr(self):
         a = array.array(self.typecode, 2*self.example)
@@ -898,8 +919,8 @@
         a = array.array(self.typecode, self.example)
         m = memoryview(a)
         expected = m.tobytes()
-        self.assertEqual(a.tostring(), expected)
-        self.assertEqual(a.tostring()[0], expected[0])
+        self.assertEqual(a.tobytes(), expected)
+        self.assertEqual(a.tobytes()[0], expected[0])
         # Resizing is forbidden when there are buffer exports.
         # For issue 4509, we also check after each error that
         # the array was not modified.
@@ -913,7 +934,7 @@
         self.assertEqual(m.tobytes(), expected)
         self.assertRaises(BufferError, a.fromlist, a.tolist())
         self.assertEqual(m.tobytes(), expected)
-        self.assertRaises(BufferError, a.fromstring, a.tostring())
+        self.assertRaises(BufferError, a.frombytes, a.tobytes())
         self.assertEqual(m.tobytes(), expected)
         if self.typecode == 'u':
             self.assertRaises(BufferError, a.fromunicode, a.tounicode())
@@ -932,7 +953,7 @@
     def test_weakref(self):
         s = array.array(self.typecode, self.example)
         p = weakref.proxy(s)
-        self.assertEqual(p.tostring(), s.tostring())
+        self.assertEqual(p.tobytes(), s.tobytes())
         s = None
         self.assertRaises(ReferenceError, len, p)
 
@@ -1110,6 +1131,23 @@
         upper = int(pow(2, a.itemsize * 8)) - 1
         self.check_overflow(lower, upper)
 
+    def test_bytes_extend(self):
+        s = bytes(self.example)
+
+        a = array.array(self.typecode, self.example)
+        a.extend(s)
+        self.assertEqual(
+            a,
+            array.array(self.typecode, self.example+self.example)
+        )
+
+        a = array.array(self.typecode, self.example)
+        a.extend(bytearray(reversed(s)))
+        self.assertEqual(
+            a,
+            array.array(self.typecode, self.example+self.example[::-1])
+        )
+
 
 class ByteTest(SignedNumberTest):
     typecode = 'b'
@@ -1172,7 +1210,7 @@
                 # On alphas treating the byte swapped bit patters as
                 # floats/doubles results in floating point exceptions
                 # => compare the 8bit string values instead
-                self.assertNotEqual(a.tostring(), b.tostring())
+                self.assertNotEqual(a.tobytes(), b.tobytes())
             b.byteswap()
             self.assertEqual(a, b)
 
diff --git a/Lib/test/test_file.py b/Lib/test/test_file.py
index 6d51fd5..ebaa38b 100644
--- a/Lib/test/test_file.py
+++ b/Lib/test/test_file.py
@@ -44,7 +44,7 @@
         a = array('b', b'x'*10)
         self.f = self.open(TESTFN, 'rb')
         n = self.f.readinto(a)
-        self.assertEquals(b'12', a.tostring()[:n])
+        self.assertEquals(b'12', a.tobytes()[:n])
 
     def testReadinto_text(self):
         # verify readinto refuses text files
@@ -281,7 +281,7 @@
             except ValueError:
                 self.fail("readinto() after next() with supposedly empty "
                           "iteration-buffer failed anyway")
-            line = buf.tostring()
+            line = buf.tobytes()
             if line != testline:
                 self.fail("readinto() after next() with empty buffer "
                           "failed. Got %r, expected %r" % (line, testline))
diff --git a/Lib/test/test_io.py b/Lib/test/test_io.py
index fc109f3..76c8536 100644
--- a/Lib/test/test_io.py
+++ b/Lib/test/test_io.py
@@ -480,7 +480,7 @@
 
     def test_array_writes(self):
         a = array.array('i', range(10))
-        n = len(a.tostring())
+        n = len(a.tobytes())
         with self.open(support.TESTFN, "wb", 0) as f:
             self.assertEqual(f.write(a), n)
         with self.open(support.TESTFN, "wb") as f:
diff --git a/Lib/test/test_memoryio.py b/Lib/test/test_memoryio.py
index 1e7d351..0decda5 100644
--- a/Lib/test/test_memoryio.py
+++ b/Lib/test/test_memoryio.py
@@ -425,7 +425,7 @@
         a = array.array('b', b"hello world")
         memio = self.ioclass(buf)
         memio.readinto(a)
-        self.assertEqual(a.tostring(), b"1234567890d")
+        self.assertEqual(a.tobytes(), b"1234567890d")
         memio.close()
         self.assertRaises(ValueError, memio.readinto, b)
 
diff --git a/Lib/test/test_memoryview.py b/Lib/test/test_memoryview.py
index 95071b5..6ca23fc 100644
--- a/Lib/test/test_memoryview.py
+++ b/Lib/test/test_memoryview.py
@@ -231,7 +231,7 @@
 class BaseArrayMemoryTests(AbstractMemoryTests):
     ro_type = None
     rw_type = lambda self, b: array.array('i', list(b))
-    getitem_type = lambda self, b: array.array('i', list(b)).tostring()
+    getitem_type = lambda self, b: array.array('i', list(b)).tobytes()
     itemsize = array.array('i').itemsize
     format = 'i'
 
diff --git a/Lib/test/test_struct.py b/Lib/test/test_struct.py
index 6ac8fdc..1151662 100644
--- a/Lib/test/test_struct.py
+++ b/Lib/test/test_struct.py
@@ -430,12 +430,12 @@
 
         # Test without offset
         s.pack_into(writable_buf, 0, test_string)
-        from_buf = writable_buf.tostring()[:len(test_string)]
+        from_buf = writable_buf.tobytes()[:len(test_string)]
         self.assertEqual(from_buf, test_string)
 
         # Test with offset.
         s.pack_into(writable_buf, 10, test_string)
-        from_buf = writable_buf.tostring()[:len(test_string)+10]
+        from_buf = writable_buf.tobytes()[:len(test_string)+10]
         self.assertEqual(from_buf, test_string[:10] + test_string)
 
         # Go beyond boundaries.
@@ -458,12 +458,12 @@
 
         # Test without offset.
         pack_into(writable_buf, 0, test_string)
-        from_buf = writable_buf.tostring()[:len(test_string)]
+        from_buf = writable_buf.tobytes()[:len(test_string)]
         self.assertEqual(from_buf, test_string)
 
         # Test with offset.
         pack_into(writable_buf, 10, test_string)
-        from_buf = writable_buf.tostring()[:len(test_string)+10]
+        from_buf = writable_buf.tobytes()[:len(test_string)+10]
         self.assertEqual(from_buf, test_string[:10] + test_string)
 
         # Go beyond boundaries.