This is part of an ongoing series of posts about how to get started writing tests for Ruby on Rails. The series begins with an introduction and overview of the ideas behind testing.

One final post about unit tests and then we will move on to functional testing.

Running All Tests in a Single Test File

Up to now we have run our unit tests by simply asking Ruby to process the file that contains our tests.

When you are first developing unit tests on a single model, this may be the easiest way to do it. It will run all the tests in the WineTest file.

Running a Single Test

What if you want to focus on one test in particular? What if your unit test file is large and takes a long time to run. Running the all the tests each time can be a waste of time.

What if you have a few tests in the file that are not finished yet? Those failures can distract and even confuse you while you work on a single test.

In these situations it would be better to run one test at a time. Ruby will do that if you include the “-n” flag (as in “name of the method”) followed by the name of the test method you want to run.

Only the test_relationships method will be executed. Even though we specified a single method, Ruby still loads in fixtures and preforms the setup method before running the test. It just ignores the other tests in the file as if they did not exist.

Running All Unit Tests

One of the benefits of writing tests is that you can test your application often and easily to ensure that everything still works. Once you have built unit tests for every model in your Rails application, it would not be considered “easy” if you had to run each and every test one by one from the command line. Can you imagine having an application with 20 or 30 models and having to test each one every time you ran the test suite? I can guarantee that it would keep you from doing it “often”.

This is where Rake is helpful. Rake allows us to make Ruby tasks easier to perform. There are a few Rake commands that you should learn. If you ever forget them, you can type rake -T from the command line while in the root of your Rails application to see a list of all available Rake commands.

Obviously, until you have written functional or integration tests, you will want to stick with rake test:units. I am simply listing all four now so that you can have them at your disposal throughout the rest of this tutorial.

The good news is: whenever you feel like you need a “sanity check” and want to run all of your tests at once, it is only a single command away! And a combination of these testing commands will provide you with some fine-grained control over which tests you run.

This entry was posted on Wednesday, February 27th, 2008 at 4:35 pm and is filed under Ruby on Rails, Tutorials. You can follow any responses to this entry through the RSS 2.0 feed. You can leave a response, or trackback from your own site.