test: refactor test-crypto-padding-aes256

* replace var with const/let
* replace assert.equal() with assert.strictEqual()

PR-URL: nodejs#10622
Reviewed-By: James M Snell <jasnell@gmail.com>
Reviewed-By: Luigi Pinca <luigipinca@gmail.com>

test/parallel/test-crypto-padding-aes256.js

@@ -11,37 +11,37 @@ const crypto = require('crypto');
 crypto.DEFAULT_ENCODING = 'buffer';
 
 function aes256(decipherFinal) {
-  var iv = Buffer.from('00000000000000000000000000000000', 'hex');
-  var key = Buffer.from('0123456789abcdef0123456789abcdef' +
-                       '0123456789abcdef0123456789abcdef', 'hex');
+  const iv = Buffer.from('00000000000000000000000000000000', 'hex');
+  const key = Buffer.from('0123456789abcdef0123456789abcdef' +
+                         '0123456789abcdef0123456789abcdef', 'hex');
 
   function encrypt(val, pad) {
-    var c = crypto.createCipheriv('aes256', key, iv);
+    const c = crypto.createCipheriv('aes256', key, iv);
     c.setAutoPadding(pad);
     return c.update(val, 'utf8', 'latin1') + c.final('latin1');
   }
 
   function decrypt(val, pad) {
-    var c = crypto.createDecipheriv('aes256', key, iv);
+    const c = crypto.createDecipheriv('aes256', key, iv);
     c.setAutoPadding(pad);
     return c.update(val, 'latin1', 'utf8') + c[decipherFinal]('utf8');
   }
 
   // echo 0123456789abcdef0123456789abcdef \
   // | openssl enc -e -aes256 -nopad -K <key> -iv <iv> \
   // | openssl enc -d -aes256 -nopad -K <key> -iv <iv>
-  var plaintext = '0123456789abcdef0123456789abcdef'; // multiple of block size
-  var encrypted = encrypt(plaintext, false);
-  var decrypted = decrypt(encrypted, false);
-  assert.equal(decrypted, plaintext);
+  let plaintext = '0123456789abcdef0123456789abcdef'; // multiple of block size
+  let encrypted = encrypt(plaintext, false);
+  let decrypted = decrypt(encrypted, false);
+  assert.strictEqual(decrypted, plaintext);
 
   // echo 0123456789abcdef0123456789abcde \
   // | openssl enc -e -aes256 -K <key> -iv <iv> \
   // | openssl enc -d -aes256 -K <key> -iv <iv>
   plaintext = '0123456789abcdef0123456789abcde'; // not a multiple
   encrypted = encrypt(plaintext, true);
   decrypted = decrypt(encrypted, true);
-  assert.equal(decrypted, plaintext);
+  assert.strictEqual(decrypted, plaintext);
 }
 
 aes256('final');