The 5 Rules of Simple RSpec Tests

The 5 “rules” I try to follow in order to write simple RSpec tests. Let’s GO. 1. Max 2 levels of describe/context nesting Everything above 2 is a code-smell and causes alarm bells in my head to ring. The more levels of nesting you have, the harder it is to understand what a given example is doing. If you add before/after hooks to the mix, it’ll become even worse. I often reduce nesting by simply using example descriptions like that:...

May 11, 2021 · 5 min · Piotr Solnica

Mocking and Ruby

In the “TDD is dead” discussion unit testing and mocking is being mentioned frequently. DHH explicitly expressed how much he dislikes mocks and it seems like many people still connect unit testing with mocking or even confuse the two. In case you missed it Martin Fowler wrote a great article about what should be considered as a unit test. If you’re also confused about mocks and stubs I encourage you to read Mocks Arent’ Stubs....

May 22, 2014 · 6 min · Piotr Solnica

TDD Is Fun

Today DHH published a blog post about TDD being dead (to him at least). It’s really not that surprising since from what I know (please correct me if I’m wrong) David’s experience is mostly based on building web apps with Rails. I get that, I really do. For me practicing TDD in a rails environment is much harder than when I work on my OSS libraries. There are many reasons why TDD in Rails is just a bit harder than it could be but that’s a big, separate subject....

April 23, 2014 · 4 min · Piotr Solnica

Common Pitfalls Of Code Metrics

Code metrics and code metric tools can be both helpful and harmful. The difference between the two is learning to interpret the results and use the feedback to improve yourself and your code. I have a lot of experience with code metric tools. Over the last couple of years I’ve used them on a daily basis. Tools measuring simple things like test coverage, lines of code [LoC] per class/method, naming, and column length along with more advanced measurements for code complexity, churn, and mutation coverage....

January 22, 2014 · 8 min · Piotr Solnica

TDD and ActiveRecord in Rails

I don’t have exact numbers but I believe TDD isn’t really popular amongst rails developers. This shouldn’t be a surprise given that the two of the most complex elements in the rails stack, models and controllers, are very convoluted concepts and are simply hard to test. When you’re building a typical rails application most of the business logic lives in the active record models and controllers. Testing controllers in rails is a bit cumbersome but I still encourage people to write tests for them....

January 6, 2014 · 5 min · Piotr Solnica

Mutation testing with Mutant

When working on DataMapper and its libraries we put a lot of effort into testing. Our libraries must have 100% code coverage and even that is not enough. What we want to achieve eventually is full mutation coverage. What is that? If you’ve ever heard or used Heckle then you’re probably familiar with the concept and you can skip the first part of this post and read about mutant. Code Coverage vs Mutation Coverage If your library has 100% code coverage and you think you did a great job then I have some bad news for you....

January 23, 2013 · 5 min · Piotr Solnica

Yes, You Should Write Controller Tests!

It really surprises me that there are people arguing that writing controller tests doesn’t make sense. Probably the most common argument is that actions are covered in acceptence tests along with checking if views are properly rendered. Right? Right…well that’s just wrong! Are you trying to say that your slow acceptance tests are covering every possible controller action scenario? Are you trying to say that, for instance, every redirect that should take place is tested within an acceptance test?...

February 2, 2012 · 5 min · Piotr Solnica

Making ActiveRecord Models Thin

“Skinny Controller, Fat Model” is a well known best practice in Ruby community. Everybody seems to agree with it and follows it. It’s pretty clear what a skinny controller is. The question is what is a fat model and what should we do if it gets too fat? Even better, what should we do to avoid too fat model? I think many people still confuse Domain Model with ActiveRecord. It’s something more and in this post I will try to explain my new approach to writing Ruby on Rails applications....

August 1, 2011 · 8 min · Piotr Solnica

Custom RSpec-2 Matchers

RSpec is one of my favorite tools. I have literally fallen in love with this fantastic BDD library, especially with its second version. While using RSpec I realized it teaches me how to write tests. Yes, exactly - learning RSpec DSL, its syntax and structure of spec examples you actually learn the best practices in writing tests. RSpec, despite many built-in matchers, comes with a DSL for defining your own, custom matchers....

January 14, 2011 · 5 min · Piotr Solnica