BerrySync: Untested code is broken code

TLDR - What did I learn?

In the irc channels I lurk, a phrase reigns true. "Untested code is broken code". I overlooked this bug because my tests didn't keep up with the code. Don't be lazy, you will not remember you took short cuts a month ago.



BerrySync's Show Stopper
 
So I'm very quick to point fingers, So naturally when our program stops decrypting 75% of the I went straight to http://bit.ly/r9vKFS. You should note RIM is abiding by this document http://bit.ly/ey4Fg and if you read further down you'll note that this algorithm padding standard does not mention AES encryption which is tragic because its the only symmetric key unformatter engine that RIM supplies, meaning you'll need it for AES encryption! For example BerrySync's crypto module sans error control:

AESKey key = new AESKey(keyData);
InitializationVector iv = new InitializationVector(ivData);
ByteArrayOutputStream outputStream = new ByteArrayOutputStream();
BlockEncryptor encryptor = new BlockEncryptor(
     new PKCS5FormatterEngine(
          new AESCBCEncryptorEngine(key, iv)), outputStream);
encryptor.write(plainText);
encryptor.close();
outputStream.close();
return outputStream.toByteArray(); 

I And you should check out http://bit.ly/rplM0s. Here you'll see that Mozilla is abiding to http://bit.ly/piPqcJ. The 2.1 standard includes AES encryption in the spec, hold on a minute. RIM must be doing something totally off the wall here. All of that combined with the knowledge that using third party and unlicensed encryption and getting your app into AppWorld would involve many headaches and much money ala ECCN.



Wrong

As with most things my finger pointing was wrong, the bug actually lived on this line

data = data.replace('-', '\0'); 

Where my lazy attempt at removing characters from a string totally backfired. The interesting thing is that during rare cases, my sync account and about 25% of others tested it didn't actually make a difference and everything worked as intended. Where the other 75% of accounts saw a Bad Padding Exception during decryption.

BerrySync - Unit Testing in Blackberry Apps

Pains
Building Berrysync from the ground up hasn't come without it's challenges. Most notably as of recent has been our incorporation of test driven development, for many people that brings JUnit to mind. To my surprise JUnit without including its dependencies will not natively run on the BlackBerry Java core, and even more interesting is the fact that JUnit comes bundled in the BlackBerry Developer Eclipse!

Thanks to some googling and blog posts lost in my browser history I came across this awesome tool called BUnit. It seems to be the only reliable way to unit test inside a BlackBerry app.

Using BUnit in Your Project
You'll need to define an alternate entry point to your application and add some logic to the App's entry point, here are the steps:

1. In BlackBerry_App_Descriptor.xml -> click Alternate entry points
2. Click add provide a name, click ok
3. Click on what you just added and provide an Application Argument and/or an icon
4. Open MyApp, and provide this logic (eg. Application Argument = bunit)

    public static void main(String[] args){
        if (args != null && args.length > 0 && args[0].equals("bunit")){
            TestRunner tester = new TestRunner();
            tester.enterEventDispatcher();
        }else{
            MyApp theApp = new MyApp();       
            theApp.enterEventDispatcher();
        }
    }

Two entry points allows this, where BerrySync is our application and B-unit is the unit tester


Tips On Usage
Now I assume the limitations of BUnit and the major benefits of JUnit come from java Reflection. Which you guessed it, isn't included in the BlackBerry JRE. Sooo much to my disappointment in each test suite you need to manually specify the number of tests, and later on invoke them in a switch. On top of that you'll need to add your suites to runner manually.

A snippet of my test suite: http://pastebin.com/mq9QzpkW


I also had to add a few Assertion functions, graciously BUnit provided the file to place them in.

assertEquals(String test, byte[] expected, byte[] actual)
assertNotEquals(String test, byte[] expected, byte[] actual)

here they are too! http://pastebin.com/H3R69XC6

ScreenShot
<- Berrysync's unit tester running as is