RSpec3でバリデーションのテスト

Faker, FactoryGirl, RSpec3を使って単純にやってみると

spec/factories/users.rb

FactoryGirl.define do
  factory :user, class: User do
    email { Faker::Internet.email }
    password { Faker::Internet.password }
  end
end

spec/models/user_spec.rb

require 'spec_helper'

describe User do
  it "should be invalid" do
    user = build(:user, { email: nil })
    expect(user.errors[:email]).to be_valid
  end
end