At the Forge - Testing with Rails

Rails provides great tools for managing test data to build and refine an application. Here's how to use them.
More Testing

The above are only two of the types of tests you might want to use on your system. Rails comes with a large collection of assertions, allowing you to test your models in a great variety of ways.

Remember that methods are just one part of the testing equation; you also will want to have appropriate integrity constraints and checks in your table definitions, and a wide variety of inputs to ensure that you are checking many different possibilities. One way to create a large number of fixtures is by creating them dynamically, using the same syntax (known as ERb, or Embedded Ruby) that is used in Rails views.

As I mentioned above, functional tests are another important element in any application's test suite. Functional tests, which operate against Rail controllers, work similarly to our unit tests—in the tests/functional directory, with one test object per controller, and with a test_ method for each method in the controller object. Testing models ensures that your data is going to be robust; testing controllers ensures that no matter what inputs you receive from users via the Web, the application will handle the situation gracefully.

Finally, Rails makes it easy to create mock objects, allowing us easily to pretend that an object has been created. For example, we might want to pretend that a credit-card transaction has gone through, or that we have sent e-mail to 50,000 users of our system, without actually carrying out the task.

Conclusion

Web applications are becoming large and sophisticated enough that they demand disciplined testing techniques to avoid unforeseen problems. Ruby on Rails comes with an integrated test system that makes it easy to create and use tests at all levels—database, model objects and controller objects. It shouldn't come as any surprise that many Ruby developers are fans of test-driven development, in part because Ruby and the Rails environment make it so easy to accomplish. If you are going to develop with Rails, it's worth taking the extra time to add tests into your application. It's easy to do, and it will save you a great deal of time later on.

Resources for this article: /article/8631.

Reuven M. Lerner, a longtime Web/database consultant and developer, now is a graduate student in the Learning Sciences program at Northwestern University. His Weblog is at altneuland.lerner.co.il, and you can reach him at reuven@lerner.co.il.

______________________

Comments

Comment viewing options

Select your preferred way to display the comments and click "Save settings" to activate your changes.

Correcting some misinformation

James G. Britt's picture

The article states, "BlogTest is a subclass of Test::Unit::TestCase, which comes with Rails ..."

Not true. Test::Unit::TestCase comes as a standard part of Ruby, and is available to all Ruby programs.

Similarly, the article says, "Notice how our test begins with the characters test_. This tells Rails that this method should be part of our test suite." This is a Test::Unit feature, and not special to Rails.

While I'm happy to see Rails get attention (though the information in recent LJ Rails articles largely duplicates what is on the Rails wiki), readers might be better served by a clearer, less Rails-centric examination of Ruby's built-in unit testing framework.

Rails *does* add in some very nice testing features (such as the fixtures method and some additional assertions), but if people are to become Ruby developers, and not just Rails scripters, they need to know these distinctions.

White Paper
Fabric-Based Computing Enables Optimized Hyperscale Data Centers

Today’s modular x86 servers are compute-centric, designed as a least common denominator to support a wide range of IT workloads. Those generic, virtualized IT workloads have much different resource optimization requirements than hyperscale and cloud applications. They have resulted in a “one size fits all” enterprise IT architecture that is not optimized for a specific set of IT workloads, and especially not emerging hyperscale workloads, such as web applications, big data, and object storage. In this report, you will learn how shifting the focus from traditional compute-centric IT architectures to an innovative disaggregated fabric-based architecture can optimize and scale your data center.

Learn More

Sponsored by AMD

White Paper
Red Hat White Paper: Using an Open Source Framework to Catch the Bad Guy

Built-in forensics, incident response, and security with Red Hat Enterprise Linux 6

Every security policy provides guidance and requirements for ensuring adequate protection of information and data, as well as high-level technical and administrative security requirements for a system in a given environment. Traditionally, providing security for a system focuses on the confidentiality of the information on it. However, protecting the data integrity and system and data availability is just as important. For example, when processing United States intelligence information, there are three attributes that require protection: confidentiality, integrity, and availability.

Learn more about catching the bad guy in this free white paper.

Learn More

Sponsored by DLT Solutions