test: improve test-child-process-exec-buffer

* use const instead of var for required modules
* use assert.strictEqual instead of assert.equal
* use assert.strictEqual instead of assert.ok
PR-URL: #10275
Reviewed-By: Colin Ihrig <cjihrig@gmail.com>
Reviewed-By: Italo A. Casas <me@italoacasas.com>

Author: edsadr

test/parallel/test-child-process-exec-buffer.js

@@ -1,22 +1,24 @@
 'use strict';
 constcommon=require('../common');
-varassert=require('assert');
-varexec=require('child_process').exec;
-varos=require('os');
-varstr='hello';
+constassert=require('assert');
+constexec=require('child_process').exec;
+constos=require('os');
+conststr='hello';
 
 // default encoding
 exec('echo '+str,common.mustCall(function(err,stdout,stderr){
-assert.ok('string',typeofstdout,'Expected stdout to be a string');
-assert.ok('string',typeofstderr,'Expected stderr to be a string');
-assert.equal(str+os.EOL,stdout);
+assert.strictEqual(typeofstdout,'string','Expected stdout to be a string');
+assert.strictEqual(typeofstderr,'string','Expected stderr to be a string');
+assert.strictEqual(str+os.EOL,stdout);
 }));
 
 // no encoding (Buffers expected)
 exec('echo '+str,{
 encoding: null
 },common.mustCall(function(err,stdout,stderr){
-assert.ok(stdoutinstanceofBuffer,'Expected stdout to be a Buffer');
-assert.ok(stderrinstanceofBuffer,'Expected stderr to be a Buffer');
-assert.equal(str+os.EOL,stdout.toString());
+assert.strictEqual(stdoutinstanceofBuffer,true,
+'Expected stdout to be a Buffer');
+assert.strictEqual(stderrinstanceofBuffer,true,
+'Expected stderr to be a Buffer');
+assert.strictEqual(str+os.EOL,stdout.toString());
 }));