Some example tests for pundit

book_group_policy.rb

class BookGroupPolicy < ApplicationPolicy
  attr_reader :user, :book_group

  def initialize(user, book_group)
    @user = user
    @book_group = book_group
  end

  def update?
    user.moderator?(book_group)
  end
end

book_group_policy_spec.rb

require 'rails_helper'

RSpec.describe BookGroupPolicy do
  let(:user) { create(:user) }
  let(:book_group) { create(:book_group) }
  let(:admin_user) { create(:user) }
  let!(:book_group_user) { BookGroupUser.create(book_group: book_group, user: admin_user, admin: true) }

  it do
    expect(Pundit.policy(user, book_group).update?).to eq false
    expect(Pundit.policy(admin_user, book_group).update?).to eq true
  end
end