Rails%203%20In%20Action

Viewing projects
Factories allow you to create new example objects for all of your models in a simple
and elegant syntax. This functionality doesn’t come with Rails, unfortunately, so you
must rely on a gem for it: factory_girl.
4.1.2 The Factory Girl
The factory_girl, created by thoughtbot, 1 provides an easy way to use factories to create
new objects for your tests. Factories define a bunch of default values for an object,
allowing you to have easily craftable objects you can use to run your tests on.
Before you can use this gem, you need to add it to the :test group in your Gemfile.
Now the whole group looks like this:
group :test do
gem 'cucumber-rails'
gem 'capybara'
gem 'database_cleaner'
gem 'factory_girl'
end
To install, run bundle. You’ll now use Factory Girl in your new step definition.
Create a new file at features/step_definitions/project_steps.rb, and add this small
chunk of code:
Given /^there is a project called "([^\"]*)"$/ do |name|
Factory(:project, :name => name)
end
The Factory method 2 looks for the :project factory and generates a new object based
on the details it contains. You don’t have a factory defined yet, but you will shortly.
When you define the factory, you give it a default name. The :name => name part
of this method call changes the default name to the one passed in from your feature.
You use factories here because you needn’t be concerned about any other attribute on
the Project object. If you weren’t using factories, you’d have to use this method to
create the object instead:
Project.create(:name => name)
Although this code is about the same length as its Factory variant, it isn’t futureproof.
If you were to add another field to the projects table and add a validation (say,
a presence one) for that field, you’d have to change all occurrences of the create
method to contain this new field. When you use factories, you can change it in one
place—where the factory is defined. If you cared about what that field was set to, you
could modify it by passing it as one of the key-value pairs in the Factory call.
That’s a lot of theory—now how about some practice? Let’s see what happens
when you run bin/cucumber features/viewing_projects.feature:
Not registered: project (ArgumentError)
1 Thoughtbot’s website: http://thoughtbot.com.
2 Yes, methods can begin with a capital letter.
85