Sunday, September 14, 2014

How I finally started writing unit tests

I'd like to talk about why it seemed so hard to get started and how I finally got past it.

I've done a lot of reading and video watching on the subject of unit testing over the last 2 years or so.  Mostly what I was getting out of it at first was, "You should be writing unit tests for all of your code.  If you aren't doing it you are a poor developer and a horrible person."  I didn't want to be either of those things so I thought I should probably start right away.

I tried several times to start, but I kept running into road blocks.  I knew from what I had watched and read that I should be able to break my code into small functions and test everything independently.  I should be able to run all my tests without actually interacting with the database or sending emails or talking to external services.  The more I looked around at my code though, the more it seemed like that was all the code did.  How could I test anything if all I was doing was interacting with external systems?

Eventually I decided to just start anyway even though it wouldn't be perfect and I would be doing actual database activity in my tests.  I couldn't see any way around it at the time, so that is where I started.  The first tests that I wrote were for a cfc that we use to access the database.  It is a general purpose object that we extend for each table in the database.  It is used all over our system though so it seemed like important code to have unit tests for.  It turned out to be a good place to start.  Because it is responsible for most of the database activity in our newer code I have been able to use that fact to remove almost all the database interaction from my tests.  I'll get into more detail about that in the next article.

I am still getting started.  I only have a couple hundred tests so far for our whole system.  I really like having them though.  Even having those few tests has allowed me to make changes to the code that I never would have made if I didn't have the tests.  It has also allowed me to make the changes necessary to remove most of the database interaction from my tests.

I'm going to stop here for now.  In the next unit testing post I will show some code and get into some more detail about how I have made changes to make unit testing easier and remove most of the external interaction that happens while testing.

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