Question

I can’t figure out why my 2nd example is passing even though it should be failing

this is my person_spec.rb:

require 'spec_helper'

describe Person do
  it "must have a first name" do
    subject { Person.new(first_name: "", last_name: "Kowalski") }
    subject.should_not be_valid
  end

  it "must have a last name" do
    subject { Person.new(first_name: "Jan") }
    subject.should_not be_valid
  end
end

this is my person.rb

class Person < ActiveRecord::Base
  attr_accessible :first_name, :last_name

  validates :first_name, presence: true

  def full_name
    return "#{@first_name}  #{@last_name}"
  end
end

My rspec output:

Person
  must have a last name
  must have a first name

Finished in 0.09501 seconds
2 examples, 0 failures

Randomized with seed 51711

What is even worse is that my further examples are failing/passing in a very unexpected way. It seems that somehow my subject is an instance of Person but with neither the first_name nor last_name assigned

Answer 1

I think you have two main issues here. First, if I’m not mistaken, you’re supposed to use subject in a group scope, but not within an actual spec. Here’s an example from the rspec docs:

describe Array, "with some elements" do
  subject { [1,2,3] }
  it "should have the prescribed elements" do
    subject.should == [1,2,3]
  end
end

Note that the subject is declared outside of the it block. So, I think it’s reasonable to see some unexpected behavior here. I haven’t dug into the source code here, but I have a feeling that would be educational.

Secondly, your specs can be greatly simplified by following these guidelines from David Chelimsky. Your spec can look more like this:

describe Person do
  it { should validate_presence_of(:first_name) }
end

Shorter, sweeter, and will probably work correctly.