Test Driven Development in Ruby on Rails using Rspec

Test Driven Development (aka TDD) is where you create test specs of expected outcomes. You can then code your way to pass these tests. The opposite of this method of coding is Behavioral Driven Development (BDD).

Setting up

First thing we need to do is install the ‘rspec-rails’ gem. We want this in the development test section in our gem file.

We can then create our rspec files using

rails g rspec:install

For this example let’s pretend we have 3 models. User, Cart, and Item.

When we use:

rails g resource Model attribute:type

The rspec file will be created for that model. To manually generate the file we can use

rails g rspec:model model_name

Creating a test

Lets create a test that totals all items in a users cart. Inside the user_spec.rb