Testing Ruby on Rails Models - Validators

Mon, 18 Jan 2016 19:08:39 -0200

In the rails way of life, all of us developers should test our code, but if you take a look on most of the companies around there, that is not totally true.

So what you can do to change that? that is simple, Start creating tests.

Yup, I know this is a stupid thing to tell, but believe me, one day you will be in a big project with no/really small test suite. Be brave :P

New projects

Please, start your project creating tests. Doesn’t matter if you’re using TDD, BDD, XYZ, just do it ;)

Already runnings projects

You came to a new company and the test suite is very small or doesn’t exist, don’t panic. You’re not going to have a easy path, but you’re not going to die.

Here is my advice:

You’re starting to understanding the project, so every class that you open, create at least the validations tests (presence, unique, inclusion_of…). If anyone remove a validation by a mistake or not, a test will break and you will know that ;)
The next step is to every method that you’re working on, you create a test before touch the code. I like to create a test that will return the expected and others to cover “unexpected” values.

On my small rails todo project, here are the initial tests. I have a task.rb and the name and related user are required.

class TaskTest < ActiveSupport::TestCase
  task = Task.new
  assert task.invalid?
  assert task.errors.include?(:name)
  assert task.errors.include?(:user)
end

I started a new object and assert that have at least one error on the required attributes.

I don’t care which error is being returned, I only care the attribute is not valid. Test a specific error became much verbose.

To make easy to test and make sure a specific attribute is being validated you could use the gem shoulda matchers. Here is a refactoring using the gem.

class TaskTest < ActiveSupport::TestCase
  should validate_presence_of(:name)
  should validate_presence_of(:user)
end

Some people will tell: “Why test validations? Are you testing if the rails validator is working?”

For some time I didn’t tested these validator because of that, till one day a validator was removed by mistake and we had a lot of problems u.u

This is why I like to do these tests ;)

Rails have a lot of validators that you can use, so keep studying, coding and testing :)

Ideas from a passionate software developer

Testing Ruby on Rails Models - Validators

New projects

Already runnings projects