test: refactor the code in test-fs-chmod

* use const and let instead of var
* use common.mustCall to control functions executions
* use assert.strictEqual instead of assert.equal
* use assert.ifError to handle errors
* use arrow functions
* remove unnecessary variables

PR-URL: https://github.com/nodejs/node/pull/10440
Reviewed-By: James M Snell <jasnell@gmail.com>
Reviewed-By: Colin Ihrig <cjihrig@gmail.com>

test/parallel/test-fs-chmod.js

@@ -1,12 +1,11 @@
 'use strict';
-var common = require('../common');
-var assert = require('assert');
-var path = require('path');
-var fs = require('fs');
-var got_error = false;
-var success_count = 0;
-var mode_async;
-var mode_sync;
+const common = require('../common');
+const assert = require('assert');
+const path = require('path');
+const fs = require('fs');
+
+let mode_async;
+let mode_sync;
 
 // Need to hijack fs.open/close to make sure that things
 // get closed once they're opened.
@@ -19,7 +18,7 @@ fs._closeSync = fs.closeSync;
 fs.close = close;
 fs.closeSync = closeSync;
 
-var openCount = 0;
+let openCount = 0;
 
 function open() {
   openCount++;
@@ -54,57 +53,49 @@ if (common.isWindows) {
 const file1 = path.join(common.fixturesDir, 'a.js');
 const file2 = path.join(common.fixturesDir, 'a1.js');
 
-fs.chmod(file1, mode_async.toString(8), function(err) {
-  if (err) {
-    got_error = true;
-  } else {
+fs.chmod(file1, mode_async.toString(8), common.mustCall((err) => {
+  assert.ifError(err);
+
   console.log(fs.statSync(file1).mode);
 
   if (common.isWindows) {
     assert.ok((fs.statSync(file1).mode & 0o777) & mode_async);
   } else {
-      assert.equal(mode_async, fs.statSync(file1).mode & 0o777);
+    assert.strictEqual(mode_async, fs.statSync(file1).mode & 0o777);
   }
 
   fs.chmodSync(file1, mode_sync);
   if (common.isWindows) {
     assert.ok((fs.statSync(file1).mode & 0o777) & mode_sync);
   } else {
-      assert.equal(mode_sync, fs.statSync(file1).mode & 0o777);
+    assert.strictEqual(mode_sync, fs.statSync(file1).mode & 0o777);
   }
-    success_count++;
-  }
-});
+}));
+
+fs.open(file2, 'a', common.mustCall((err, fd) => {
+  assert.ifError(err);
+
+  fs.fchmod(fd, mode_async.toString(8), common.mustCall((err) => {
+    assert.ifError(err);
 
-fs.open(file2, 'a', function(err, fd) {
-  if (err) {
-    got_error = true;
-    console.error(err.stack);
-    return;
-  }
-  fs.fchmod(fd, mode_async.toString(8), function(err) {
-    if (err) {
-      got_error = true;
-    } else {
     console.log(fs.fstatSync(fd).mode);
 
     if (common.isWindows) {
       assert.ok((fs.fstatSync(fd).mode & 0o777) & mode_async);
     } else {
-        assert.equal(mode_async, fs.fstatSync(fd).mode & 0o777);
+      assert.strictEqual(mode_async, fs.fstatSync(fd).mode & 0o777);
     }
 
     fs.fchmodSync(fd, mode_sync);
     if (common.isWindows) {
       assert.ok((fs.fstatSync(fd).mode & 0o777) & mode_sync);
     } else {
-        assert.equal(mode_sync, fs.fstatSync(fd).mode & 0o777);
+      assert.strictEqual(mode_sync, fs.fstatSync(fd).mode & 0o777);
     }
-      success_count++;
+
     fs.close(fd);
-    }
-  });
-});
+  }));
+}));
 
 // lchmod
 if (fs.lchmod) {
@@ -113,26 +104,20 @@ if (fs.lchmod) {
   common.refreshTmpDir();
   fs.symlinkSync(file2, link);
 
-  fs.lchmod(link, mode_async, function(err) {
-    if (err) {
-      got_error = true;
-    } else {
+  fs.lchmod(link, mode_async, common.mustCall((err) => {
+    assert.ifError(err);
+
     console.log(fs.lstatSync(link).mode);
-      assert.equal(mode_async, fs.lstatSync(link).mode & 0o777);
+    assert.strictEqual(mode_async, fs.lstatSync(link).mode & 0o777);
 
     fs.lchmodSync(link, mode_sync);
-      assert.equal(mode_sync, fs.lstatSync(link).mode & 0o777);
-      success_count++;
-    }
-  });
-} else {
-  success_count++;
+    assert.strictEqual(mode_sync, fs.lstatSync(link).mode & 0o777);
+
+  }));
 }
 
 
 process.on('exit', function() {
-  assert.equal(3, success_count);
-  assert.equal(0, openCount);
-  assert.equal(false, got_error);
+  assert.strictEqual(0, openCount);
 });