Why is Application Record changing my RSpec Test result

Question

Reasonably green to testing but I was following along with a simple udemy course. I used the RSpec documentation to set up RSpec in rails to try out some testing. But I have come across an issue that for the life of me I can't figure out...

require "rails_helper"

RSpec.describe User, type: :model do
  subject { described_class.new("John") }

  it "initializes a name" do
    expect(subject.name).to eq("John")
  end

  context "with no argument" do
    subject { described_class.new }

    it "should default to Bill as the name" do
      expect(subject.name).to eq("Bill")
    end
  end
end

# This is my test code. 

# This is my User model. 

class User < ApplicationRecord
  attr_reader :name

  def initialize(name = "Bill")
    @name = name
  end
end

When I run the test it fails and says that the second test isn't returning Bill but 'nil'. However, in my User model if I remove the < Application Record it passes... Also, if I add a second parameter in the initialize, it randomly passes the default test and fails the first one returning the default name... I'm completely confused as I have been learning the testing without ApplicationRecord and that seems to be the part where it is failing. I have tried changing the subject to let(:testing){User.new} but that doesn't work. Any help seriously appreciated here as I can't seem to find it through google.

To let you know I have gem 'rspec-rails', '~> 4.0.0' included in my GemFile in the :development, :test part.

Answer 1

You are trying to override default initializer of a model and you doing it the wrong way. When you call new on ActiveRecord class you need to pass a hash of parameters. To have name field in a model you need to define it in DB schema.

Creation of an instance of User for the first test case should look like this:

described_class.new(name: "John")

I see these ways to have a default value for an attribute:

Set it using a callback

class User < ApplicationRecord
  after_initialize :set_name

  private

  def set_name
    self.name ||= 'Bill' # Set name to Bill if it is nil
  end
end

Override initialize method.

# Please avoid this approach
class User < ApplicationRecord
  def initialize(*args)
    super # This will initiate default behaviour of a model
    self.name ||= 'Bill' 
  end
end

Using attributes API as @engineersmnky suggested

class User < ApplicationRecord
  attribute :name, :string, default: 'Bill'
end

I strongly recommend using a callback or attributes API approach to not broke default behaviour.

After that, your tests should pass I believe.