Fix typos mostly in comments, docs and test names (GH-15209)

diff --git a/Lib/test/test_hmac.py b/Lib/test/test_hmac.py
index 896bbe9..f2eb6d7 100644
--- a/Lib/test/test_hmac.py
+++ b/Lib/test/test_hmac.py
@@ -445,7 +445,7 @@
         a, b = bytearray(b"foobar"), bytearray(b"foobar")
         self.assertTrue(hmac.compare_digest(a, b))
 
-        # Testing bytearrays of diffeent lengths
+        # Testing bytearrays of different lengths
         a, b = bytearray(b"foobar"), bytearray(b"foo")
         self.assertFalse(hmac.compare_digest(a, b))
 
@@ -458,7 +458,7 @@
         self.assertTrue(hmac.compare_digest(a, b))
         self.assertTrue(hmac.compare_digest(b, a))
 
-        # Testing byte bytearray of diffeent lengths
+        # Testing byte bytearray of different lengths
         a, b = bytearray(b"foobar"), b"foo"
         self.assertFalse(hmac.compare_digest(a, b))
         self.assertFalse(hmac.compare_digest(b, a))
@@ -472,7 +472,7 @@
         a, b = "foobar", "foobar"
         self.assertTrue(hmac.compare_digest(a, b))
 
-        # Testing str of diffeent lengths
+        # Testing str of different lengths
         a, b = "foo", "foobar"
         self.assertFalse(hmac.compare_digest(a, b))