test: refactor test-fs-write.js

Changed var to const and equal to strictEqual

PR-URL: nodejs#9982
Reviewed-By: Colin Ihrig <cjihrig@gmail.com>
Reviewed-By: James M Snell <jasnell@gmail.com>

test/parallel/test-fs-write.js

@@ -1,26 +1,26 @@
 'use strict';
-var common = require('../common');
-var assert = require('assert');
-var path = require('path');
-var Buffer = require('buffer').Buffer;
-var fs = require('fs');
-var fn = path.join(common.tmpDir, 'write.txt');
-var fn2 = path.join(common.tmpDir, 'write2.txt');
-var expected = 'ümlaut.';
-var constants = fs.constants;
+const common = require('../common');
+const assert = require('assert');
+const path = require('path');
+const Buffer = require('buffer').Buffer;
+const fs = require('fs');
+const fn = path.join(common.tmpDir, 'write.txt');
+const fn2 = path.join(common.tmpDir, 'write2.txt');
+const expected = 'ümlaut.';
+const constants = fs.constants;
 
 common.refreshTmpDir();
 
 fs.open(fn, 'w', 0o644, common.mustCall(function(err, fd) {
   if (err) throw err;
   console.log('open done');
   fs.write(fd, '', 0, 'utf8', function(err, written) {
-    assert.equal(0, written);
+    assert.strictEqual(0, written);
   });
   fs.write(fd, expected, 0, 'utf8', common.mustCall(function(err, written) {
     console.log('write done');
     if (err) throw err;
-    assert.equal(Buffer.byteLength(expected), written);
+    assert.strictEqual(Buffer.byteLength(expected), written);
     fs.closeSync(fd);
     const found = fs.readFileSync(fn, 'utf8');
     console.log('expected: "%s"', expected);
@@ -36,12 +36,12 @@ fs.open(fn2, constants.O_CREAT | constants.O_WRONLY | constants.O_TRUNC, 0o644,
           if (err) throw err;
           console.log('open done');
           fs.write(fd, '', 0, 'utf8', (err, written) => {
-            assert.equal(0, written);
+            assert.strictEqual(0, written);
           });
           fs.write(fd, expected, 0, 'utf8', common.mustCall((err, written) => {
             console.log('write done');
             if (err) throw err;
-            assert.equal(Buffer.byteLength(expected), written);
+            assert.strictEqual(Buffer.byteLength(expected), written);
             fs.closeSync(fd);
             const found = fs.readFileSync(fn2, 'utf8');
             console.log('expected: "%s"', expected);