test: add test for repl.defineCommand()

It also tests displayPrompt by checking for '> '.
PR-URL: #3908
Reviewed-By: James M Snell <jasnell@gmail.com>
Reviewed-By: Sakthipriyan Vairamani <thechargingvolcano@gmail.com>
Reviewed-By: Jeremiah Senkpiel <fishrock123@rocketmail.com>

Author: bengl

test/parallel/test-repl-definecommand.js

@@ -0,0 +1,43 @@
+'use strict';
+
+require('../common');
+
+conststream=require('stream'),
+assert=require('assert'),
+repl=require('repl');
+
+varoutput='';
+constinputStream=newstream.PassThrough();
+constoutputStream=newstream.PassThrough();
+outputStream.on('data',function(d){
+output+=d;
+});
+
+constr=repl.start({
+input: inputStream,
+output: outputStream,
+terminal: true
+});
+
+r.defineCommand('say1',{
+help: 'help for say1',
+action: function(thing){
+output='';
+this.write('hello '+thing);
+this.displayPrompt();
+}
+});
+
+r.defineCommand('say2',function(){
+output='';
+this.write('hello from say2');
+this.displayPrompt();
+});
+
+inputStream.write('.help\n');
+assert(/\nsay1\thelpforsay1\n/.test(output),'help for say1 not present');
+assert(/\nsay2\t\n/.test(output),'help for say2 not present');
+inputStream.write('.say1 node developer\n');
+assert(/>hellonodedeveloper/.test(output),'say1 outputted incorrectly');
+inputStream.write('.say2 node developer\n');
+assert(/>hellofromsay2/.test(output),'say2 outputted incorrectly');