test: refactor test-repl-mode.js

* var -> const/let
* assert.equal() -> assert.strictEqual()

PR-URL: nodejs#10061
Reviewed-By: Evan Lucas <evanlucas@me.com>
Reviewed-By: Colin Ihrig <cjihrig@gmail.com>
Reviewed-By: Jeremiah Senkpiel <fishrock123@rocketmail.com>

test/parallel/test-repl-mode.js

@@ -1,12 +1,12 @@
 'use strict';
-var common = require('../common');
-var assert = require('assert');
-var Stream = require('stream');
-var repl = require('repl');
+const common = require('../common');
+const assert = require('assert');
+const Stream = require('stream');
+const repl = require('repl');
 
 common.globalCheck = false;
 
-var tests = [
+const tests = [
   testSloppyMode,
   testStrictMode,
   testAutoMode
@@ -17,22 +17,22 @@ tests.forEach(function(test) {
 });
 
 function testSloppyMode() {
-  var cli = initRepl(repl.REPL_MODE_SLOPPY);
+  const cli = initRepl(repl.REPL_MODE_SLOPPY);
 
   cli.input.emit('data', `
     x = 3
   `.trim() + '\n');
-  assert.equal(cli.output.accumulator.join(''), '> 3\n> ');
+  assert.strictEqual(cli.output.accumulator.join(''), '> 3\n> ');
   cli.output.accumulator.length = 0;
 
   cli.input.emit('data', `
     let y = 3
   `.trim() + '\n');
-  assert.equal(cli.output.accumulator.join(''), 'undefined\n> ');
+  assert.strictEqual(cli.output.accumulator.join(''), 'undefined\n> ');
 }
 
 function testStrictMode() {
-  var cli = initRepl(repl.REPL_MODE_STRICT);
+  const cli = initRepl(repl.REPL_MODE_STRICT);
 
   cli.input.emit('data', `
     x = 3
@@ -44,30 +44,30 @@ function testStrictMode() {
   cli.input.emit('data', `
     let y = 3
   `.trim() + '\n');
-  assert.equal(cli.output.accumulator.join(''), 'undefined\n> ');
+  assert.strictEqual(cli.output.accumulator.join(''), 'undefined\n> ');
 }
 
 function testAutoMode() {
-  var cli = initRepl(repl.REPL_MODE_MAGIC);
+  const cli = initRepl(repl.REPL_MODE_MAGIC);
 
   cli.input.emit('data', `
     x = 3
   `.trim() + '\n');
-  assert.equal(cli.output.accumulator.join(''), '> 3\n> ');
+  assert.strictEqual(cli.output.accumulator.join(''), '> 3\n> ');
   cli.output.accumulator.length = 0;
 
   cli.input.emit('data', `
     let y = 3
   `.trim() + '\n');
-  assert.equal(cli.output.accumulator.join(''), 'undefined\n> ');
+  assert.strictEqual(cli.output.accumulator.join(''), 'undefined\n> ');
 }
 
 function initRepl(mode) {
-  var input = new Stream();
+  const input = new Stream();
   input.write = input.pause = input.resume = function() {};
   input.readable = true;
 
-  var output = new Stream();
+  const output = new Stream();
   output.write = output.pause = output.resume = function(buf) {
     output.accumulator.push(buf);
   };