Sunday, September 26, 2010

A Break for Bugs

I am going to delay the planned installment of Animating the Canvas this week. While I have made a lot of progress on the code and thought that I had the rest of this series finished, when using the code within my Tarot project, some bugs were uncovered. While I could continue the series anyway, as the planned topic for today would not have been related to the issue at hand, I have decided instead to take a brief break and discus testing.

Testing and debugging are an important part of programming. The testing requirements largely depend on the project. Being old-school, I tend to use my brain to do the bulk of my debugging. I try and think like the computer to figure out where the problem is and then isolate and solve the problem. I find this approach much faster than the second level of debugging, namely using a debugger. Firefox, thankfully, has an incredible debugger called firebug. Apple has pretty much cloned this tool for Safari. Still, as someone who uses multiple operating systems, I like the fact that Firefox is everywhere so tend to use that browser for my preliminary testing. Single stepping through a program can be very time-consuming but for some bugs it is a necessity.

The big trend now is something called unit testing. It is an approach that is really good and is something that I should be doing more of but as most my projects are small I don't. The idea here is that you write your tests before you write your code. The tests are usually written using some type of testing framework in mind. Because the tests are all automated, you simply need to run the tests before checking in code. The advantage to using this technique is that you know when you are done as all of your tests are successful. For game development, this is only a partial solution. You can test the subsystems that make up the game, but are still going to need human testing for a lot of the testing.

While unit testing is not the silver bullet a lot of people think, the automated tests do help you make progress if you have written them. If you have not and are debugging things, unit tests can still prove useful. Once you have isolated a bug, or started writing testing code to help find the bug, you will have automated tests that make sure you do not re-introduce the bug in the future. While I am sure there are countless JavaScript testing frameworks available, creating one is very simple. Here is the one I wrote after discovering my issues with the BGLayers library I am writing:

function addTestResult(group, desc, result)
    var testTable = document.getElementById('testTable');
    var rRow = testTable.insertRow(1);
    var resText;
    if ( result)
        resText = 'Test Passed';
        resText = 'Test Failed';
    rRow.innerHTML = ''+group+''+desc+''+resText+'';

Yes, I could have searched out a much better one online, but was simply too lazy to. My own "framework" only took a few minutes to write. I am sure that as I continue to focus more on writing JavaScript, especially as I start larger projects,  finding a better library for unit testing will make sense. For now, my simple test function is adequate for my needs.

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