Undefined Wrapper Method - ruby-on-rails

Question

I'm having a trouble understanding why I cannot successfully call my wrapper method in my User model. My problem lies with this line self.password_hash = hash_check(password, password_salt) in the encrypt_password method shown below. My hash_check method works correctly in the authenticate method so I'm a bit stumped. When I run my test I get the error undefined method 'hash_check' for #<User:0x007f94851a5f88>
class User < ActiveRecord::Base
attr_accessor :password
before_save :encrypt_password
validates_confirmation_of :password
validates_presence_of :password, :on => :create
validates_presence_of :email
validates_uniqueness_of :email
def encrypt_password
if password.present?
self.password_salt = generate_salt
self.password_hash = hash_check(password, password_salt)
end
end
def self.authenticate(email, password)
user = find_user(email)
user && user.password_hash == hash_check(password, user.password_salt) ? user : nil
end
def self.find_user(email)
user = find_by_email(email)
end
private
def self.hash_check(password, password_salt)
BCrypt::Engine.hash_secret(password, password_salt)
end
def generate_salt
BCrypt::Engine.generate_salt
end
end
require 'spec_helper'
describe 'User' do
let(:user) { User.create(email: 'user#gmail.com', password: "secure_password") }
it 'creates a user object' do
user.should be_kind_of User
end
describe '.find_user' do
let(:valid_user_search) { User.find_user('user#gmail.com') }
let(:invalid_user_search) { User.find_user('notregistered#gmail.com') }
it 'returns a user by their email' do
user.should == valid_user_search
end
it 'return nil if no user if found' do
invalid_user_search.should == nil
end
end
describe '.authenticate' do
let(:auth_user) { User.authenticate(user.email, user.password) }
let(:non_auth_user) { User.authenticate('notregistered#gmail.com', 'invalidpass') }
it 'returns an valid user' do
auth_user.should == user
end
it 'returns nil on an invalid user' do
non_auth_user.should == nil
end
end
describe '.encrypt_password' do
it 'returns a password salt'
it 'return a password hash'
end
end

Answer 1

self.hash_check is a class method (because you put self). It works in self.authenticate because it is also a class method, (as it doesn't rely on an instance). HOWEVER, it won't work on an instance method like encrypt_password because you are not invoking the class method at all.
So you are going to need to replace hash_check(password, password_salt) in your instance method with self.class.hash_check(password, password_salt) or User.hash_check(password, password_salt) to be able to use a class method
Read more about the nuances here