test: strictCompare and explcit inputs mprovement to test-buffer-slice

* change implicit string equal() compares to strictEqual compares of
  buffer output (the slice output default)
* explicitly create buffers from utf8 inputs for the compare

PR-URL: nodejs#10048
Reviewed-By: James M Snell <jasnell@gmail.com>

test/parallel/test-buffer-slice.js

@@ -3,52 +3,83 @@
 require('../common');
 const assert = require('assert');
 
-assert.strictEqual(0, Buffer.from('hello').slice(0, 0).length);
-assert.strictEqual(0, Buffer('hello').slice(0, 0).length);
+assert.strictEqual(0, Buffer.from('hello', 'utf8').slice(0, 0).length);
+assert.strictEqual(0, Buffer('hello', 'utf8').slice(0, 0).length);
 
-const buf = Buffer.from('0123456789');
-assert.equal(buf.slice(-10, 10), '0123456789');
-assert.equal(buf.slice(-20, 10), '0123456789');
-assert.equal(buf.slice(-20, -10), '');
-assert.equal(buf.slice(), '0123456789');
-assert.equal(buf.slice(0), '0123456789');
-assert.equal(buf.slice(0, 0), '');
-assert.equal(buf.slice(undefined), '0123456789');
-assert.equal(buf.slice('foobar'), '0123456789');
-assert.equal(buf.slice(undefined, undefined), '0123456789');
+const buf = Buffer.from('0123456789', 'utf8');
+assert.strictEqual(0, Buffer.compare(buf.slice(-10, 10),
+  Buffer.from('0123456789', 'utf8')));
+assert.strictEqual(0, Buffer.compare(buf.slice(-20, 10),
+  Buffer.from('0123456789', 'utf8')));
+assert.strictEqual(0, Buffer.compare(buf.slice(-20, -10),
+  Buffer.from('', 'utf8')));
+assert.strictEqual(0, Buffer.compare(buf.slice(),
+  Buffer.from('0123456789', 'utf8')));
+assert.strictEqual(0, Buffer.compare(buf.slice(0),
+  Buffer.from('0123456789', 'utf8')));
+assert.strictEqual(0, Buffer.compare(buf.slice(0, 0),
+  Buffer.from('', 'utf8')));
+assert.strictEqual(0, Buffer.compare(buf.slice(undefined),
+  Buffer.from('0123456789', 'utf8')));
+assert.strictEqual(0, Buffer.compare(buf.slice('foobar'),
+  Buffer.from('0123456789', 'utf8')));
+assert.strictEqual(0, Buffer.compare(buf.slice(undefined, undefined),
+  Buffer.from('0123456789', 'utf8')));
 
-assert.equal(buf.slice(2), '23456789');
-assert.equal(buf.slice(5), '56789');
-assert.equal(buf.slice(10), '');
-assert.equal(buf.slice(5, 8), '567');
-assert.equal(buf.slice(8, -1), '8');
-assert.equal(buf.slice(-10), '0123456789');
-assert.equal(buf.slice(0, -9), '0');
-assert.equal(buf.slice(0, -10), '');
-assert.equal(buf.slice(0, -1), '012345678');
-assert.equal(buf.slice(2, -2), '234567');
-assert.equal(buf.slice(0, 65536), '0123456789');
-assert.equal(buf.slice(65536, 0), '');
-assert.equal(buf.slice(-5, -8), '');
-assert.equal(buf.slice(-5, -3), '56');
-assert.equal(buf.slice(-10, 10), '0123456789');
-for (let i = 0, s = buf.toString(); i < buf.length; ++i) {
-  assert.equal(buf.slice(i), s.slice(i));
-  assert.equal(buf.slice(0, i), s.slice(0, i));
-  assert.equal(buf.slice(-i), s.slice(-i));
-  assert.equal(buf.slice(0, -i), s.slice(0, -i));
+assert.strictEqual(0, Buffer.compare(buf.slice(2),
+  Buffer.from('23456789', 'utf8')));
+assert.strictEqual(0, Buffer.compare(buf.slice(5),
+  Buffer.from('56789', 'utf8')));
+assert.strictEqual(0, Buffer.compare(buf.slice(10),
+  Buffer.from('', 'utf8')));
+assert.strictEqual(0, Buffer.compare(buf.slice(5, 8),
+  Buffer.from('567', 'utf8')));
+assert.strictEqual(0, Buffer.compare(buf.slice(8, -1),
+  Buffer.from('8', 'utf8')));
+assert.strictEqual(0, Buffer.compare(buf.slice(-10),
+  Buffer.from('0123456789', 'utf8')));
+assert.strictEqual(0, Buffer.compare(buf.slice(0, -9),
+  Buffer.from('0', 'utf8')));
+assert.strictEqual(0, Buffer.compare(buf.slice(0, -10),
+  Buffer.from('', 'utf8')));
+assert.strictEqual(0, Buffer.compare(buf.slice(0, -1),
+  Buffer.from('012345678', 'utf8')));
+assert.strictEqual(0, Buffer.compare(buf.slice(2, -2),
+  Buffer.from('234567', 'utf8')));
+assert.strictEqual(0, Buffer.compare(buf.slice(0, 65536),
+  Buffer.from('0123456789', 'utf8')));
+assert.strictEqual(0, Buffer.compare(buf.slice(65536, 0),
+  Buffer.from('', 'utf8')));
+assert.strictEqual(0, Buffer.compare(buf.slice(-5, -8),
+  Buffer.from('', 'utf8')));
+assert.strictEqual(0, Buffer.compare(buf.slice(-5, -3),
+  Buffer.from('56', 'utf8')));
+assert.strictEqual(0, Buffer.compare(buf.slice(-10, 10),
+  Buffer.from('0123456789', 'utf8')));
+for (let i = 0, s = buf; i < buf.length; ++i) {
+  assert.strictEqual(0, Buffer.compare(buf.slice(i), s.slice(i)));
+  assert.strictEqual(0, Buffer.compare(buf.slice(0, i), s.slice(0, i)));
+  assert.strictEqual(0, Buffer.compare(buf.slice(-i), s.slice(-i)));
+  assert.strictEqual(0, Buffer.compare(buf.slice(0, -i), s.slice(0, -i)));
 }
 
 const utf16Buf = Buffer.from('0123456789', 'utf16le');
 assert.deepStrictEqual(utf16Buf.slice(0, 6), Buffer.from('012', 'utf16le'));
 
-assert.equal(buf.slice('0', '1'), '0');
-assert.equal(buf.slice('-5', '10'), '56789');
-assert.equal(buf.slice('-10', '10'), '0123456789');
-assert.equal(buf.slice('-10', '-5'), '01234');
-assert.equal(buf.slice('-10', '-0'), '');
-assert.equal(buf.slice('111'), '');
-assert.equal(buf.slice('0', '-111'), '');
+assert.strictEqual(0, Buffer.compare(buf.slice('0', '1'),
+  Buffer.from('0', 'utf8')));
+assert.strictEqual(0, Buffer.compare(buf.slice('-5', '10'),
+  Buffer.from('56789', 'utf8')));
+assert.strictEqual(0, Buffer.compare(buf.slice('-10', '10'),
+  Buffer.from('0123456789', 'utf8')));
+assert.strictEqual(0, Buffer.compare(buf.slice('-10', '-5'),
+  Buffer.from('01234', 'utf8')));
+assert.strictEqual(0, Buffer.compare(buf.slice('-10', '-0'),
+  Buffer.from('', 'utf8')));
+assert.strictEqual(0, Buffer.compare(buf.slice('111'),
+  Buffer.from('', 'utf8')));
+assert.strictEqual(0, Buffer.compare(buf.slice('0', '-111'),
+  Buffer.from('', 'utf8')));
 
 // try to slice a zero length Buffer
 // see https://github.com/joyent/node/issues/5881
@@ -57,30 +88,32 @@ assert.strictEqual(Buffer.alloc(0).slice(0, 1).length, 0);
 
 {
   // Single argument slice
-  assert.strictEqual('bcde', Buffer.from('abcde').slice(1).toString());
+  assert.strictEqual('bcde',
+                     Buffer.from('abcde', 'utf8').slice(1).toString('utf8'));
 }
 
 // slice(0,0).length === 0
-assert.strictEqual(0, Buffer.from('hello').slice(0, 0).length);
+assert.strictEqual(0, Buffer.from('hello', 'utf8').slice(0, 0).length);
 
 {
   // Regression tests for https://github.com/nodejs/node/issues/9096
-  const buf = Buffer.from('abcd');
-  assert.strictEqual(buf.slice(buf.length / 3).toString(), 'bcd');
+  const buf = Buffer.from('abcd', 'utf8');
+  assert.strictEqual(buf.slice(buf.length / 3).toString('utf8'), 'bcd');
   assert.strictEqual(
     buf.slice(buf.length / 3, buf.length).toString(),
     'bcd'
   );
 }
 
 {
-  const buf = Buffer.from('abcdefg');
-  assert.strictEqual(buf.slice(-(-1 >>> 0) - 1).toString(), buf.toString());
+  const buf = Buffer.from('abcdefg', 'utf8');
+  assert.strictEqual(buf.slice(-(-1 >>> 0) - 1).toString('utf8'),
+                     buf.toString('utf8'));
 }
 
 {
-  const buf = Buffer.from('abc');
-  assert.strictEqual(buf.slice(-0.5).toString(), buf.toString());
+  const buf = Buffer.from('abc', 'utf8');
+  assert.strictEqual(buf.slice(-0.5).toString('utf8'), buf.toString('utf8'));
 }
 
 {