I wouldn't bother with unit testing. I had 100% code coverage but I didn't get the "bonus points". Try to encapsulate every single array to a class (Don't ask why) they don't like to see members in a class but they want everything in a separate class.

No I didn't pass the coding exercise because I used 1 2D array inside my class and I didn't create another class for this array.

wow that sucks

Yup. I didn't understand their evaluation really but apparently many people have passed the coding exercise. I work for a bigger company and I used the same architecture as I use at work daily, which is guided by architects at my current job. They didn't like it :)

That's a pretty big bummer if you solved the problem and they were hung up on one thing.