Sunday, November 15, 2009

Testing with IronPython

We all know that unit testing is important with software development. But the tests themselves are not always so black and white. IDEs like SharpDevelop or MonoDevelop have things like NUnit to help test a wide range of things like equality, identity, collection, and etc. These are great tools, but what happens when you don't know what the data being gathered/generated should be? How can we assert something when we don't know what it should be?

My situation was this, I wrote a C# library for work to pull customer information and create reports based on the customer's monthly fees. Since the fees vary between customers, it was difficult to make sure that the data being pulled was accurate. Since I have been losing time with this portion of the project, I decided it would be a good time to test the abilities of Iron Python.

Why use Iron Python? Couple of reasons. First, since this is a .NET project, Iron Python can load the library through the clr.AddReferenceToFile command. Second, it can be ran as a script rather than compiling a new C# project. This means that I can alter/update the script and rerun it when I need to. Nice convenience.

What I did was write a script to pull in the .dll library and call the various objects to display the information stored in them in an organized way. Like so...

import sys,clr

from System import *

if __name__ == '__main__':

    dllPath = Environment.CurrentDirectory.ToString() + r'\bin\Debug'


    from nameOfNamespace import *

    print "Start going through the objects..."
From here, I can create test objects from the dll and see if what data is being pulled and confirm it with external sources to make sure it is accurate. The first time I ran it, I found (and corrected) a few missteps on my part. Within the first 30 minutes of running it, I was able to fix problems that would have taken me much longer in the final product. Pretty cool.

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