Test for destroying associated records when object is destroyed failing in rails app

Question

Im stuck on the test in listing 10.15 of Michael Hartls ruby on rails tutorial (http://ruby.railstutorial.org/chapters/user-microposts#code-micropost_dependency_test). My user_spec.rb is as follows

require 'spec_helper'

describe User do
  before { @user = User.new(name: "Example User", email: "[email protected]",password: "foobar", password_confirmation: "foobar") }

  subject { @user }

  it { should respond_to(:name) }
  it { should respond_to(:email) }
  it { should respond_to(:password_digest) }
  it { should respond_to(:password) }
  it { should respond_to(:password_confirmation) }
  it { should respond_to(:remember_token) }
  it { should respond_to(:admin) }
  it { should respond_to(:authenticate) }
  it { should respond_to(:microposts) }

  it { should be_valid }
  it { should_not be_admin }

  describe "with admin attribute set to 'true'" do
    before do
      @user.save!
      @user.toggle!(:admin)
    end

    it { should be_admin }
  end

  describe "when name is not present" do
    before { @user.name = " " }
    it { should_not be_valid }
  end

  describe "when email is not present" do
    before { @user.email = " " }
    it { should_not be_valid }
  end

  describe "when name is too long" do
    before { @user.name = "a" * 51 }
    it { should_not be_valid }
  end

  describe "when email format is invalid" do
    it "should be invalid" do
      addresses = %w[user@foo,com user_at_foo.org example.user@foo. foo@bar_baz.com foo@bar+baz.com]
      addresses.each do |invalid_address|
        @user.email = invalid_address
        @user.should_not be_valid
      end
    end
  end

  describe "when email format is valid" do
    it "should be valid" do
      addresses = %w[[email protected] [email protected] [email protected] [email protected]]
      addresses.each do |valid_address|
        @user.email = valid_address
        @user.should be_valid
      end
    end
  end

  describe "when email address is already taken" do
    before do
      user_with_same_email = @user.dup
      user_with_same_email.email = @user.email.upcase
      user_with_same_email.save
    end

    it { should_not be_valid }
  end

  describe "when password is not present" do
    before { @user.password = @user.password_confirmation = " "}
    it { should_not be_valid }
  end

  describe "when password doesn't match confirmation" do
    before { @user.password_confirmation = "mismatch" }
    it { should_not be_valid }
  end

  describe "when password confirmation is nil" do
    before { @user.password_confirmation = nil }
    it { should_not be_valid }
  end

  describe "return value of authenticate method" do
    before { @user.save }
    let(:found_user) { User.find_by_email(@user.email) }

    describe "with valid password" do
      it { should == found_user.authenticate(@user.password) }
    end

    describe "with invalid password" do
      let(:user_for_invalid_password) { found_user.authenticate("invalid") }
      it { should_not == user_for_invalid_password }
      specify { user_for_invalid_password.should be_false }
    end
  end

  describe "with a password that's too short" do
    before { @user.password = @user.password_confirmation = "a" * 5 }
    it { should be_invalid }
  end

  describe "remember token" do
    before { @user.save }
    its(:remember_token) { should_not be_blank }
  end

  describe "micropost associations" do
    before { @user.save }
    let!(:older_micropost) do
      FactoryGirl.create(:micropost, user:@user, created_at: 1.day.ago)
    end
    let!(:newer_micropost) do
      FactoryGirl.create(:micropost, user:@user, created_at: 1.hour.ago)
    end

    it "should have the right microposts in the right order" do
      @user.microposts.should == [newer_micropost, older_micropost]
    end

    it "should destroy the associated microposts" do
      microposts = @user.microposts.dup
      @user.destroy
      microposts.should_not be_empty
      microposts.each do |micropost|
        Micropost.find_by_id(micropost.id).should be_nil
      end
    end
  end

end

When i run the tests i get the following error :

  1) User micropost associations should destroy the associated microposts
     Failure/Error: Micropost.find_by_id(micropost.id).should be_nil
       expected: nil
            got: #<Micropost id: 2, content: "Lorem ipsum", user_id: nil, created_at: "2012-12-19 09:49:24", updated_at: "2012-12-19 10:49:24">
     # ./spec/models/user_spec.rb:133:in `block (4 levels) in <top (required)>'
     # ./spec/models/user_spec.rb:132:in `each'
     # ./spec/models/user_spec.rb:132:in `block (3 levels) in <top (required)>'

In my user.rb i have added the dependent :destroy as follows, which is required for the test to pass.

has_many :microposts, dependent: :destroy

Why is the test still failing ?

Thank You

Answer 1

I would encourage you not to do something like:

expect { @user.destroy }.to change(User, :count).by(-1)

This only tests the any user was deleted, it does not confirm that the correct records were deleted. Instead, I would do something like this

@user.destroy
expect { @user.reload }.to raise_error ActiveRecord::RecordNotFound

This ensures the correct user was deleted.

Answer 2

Consider testing with a more abbreviated expect .. to change test:

it "destroys the associated microposts" do
  expect { @user.destroy }.to change(Micropost, :count).by(-2)
end

Replace the -2 with whatever change value you'd expect. For example, if it deletes 1 Micropost record, then change it to -1.