Writing tests are good. Writing slow tests are frustrating for continuous deployment. Your test suite runs before you can deploy and this means that deployments can take additional 5-10 minutes because of slow tests. One of the things that I am most proud of in the past month is dramatically speeding up our test suite. We went from a full test suite take approximately 8-9 minutes to our test suite taking about 5 minutes! Thus, the feedback loop of producing code, checking in code, and deploying code to staging is a lot faster.
The biggest improvement in our test suite came after I read this article about factory_girl. The major argument in this article is that if you are building test objects that do not need to hit the database, you do not need to create the object. Instead, you can build_stubbed the object, which instantiates and assigns attributes to an object to make it look like its been persisted. But, since it does not actually get persisted into the test database, it dramatically speeds up your tests.
This takes 0.46449 seconds.
This takes 0.05353 seconds.
There are times when you will want to create objects in testing, but default to using build_stubbed, it will greatly reduce your test suite!