gistfile1.txt

require 'rails_helper'

RSpec.describe "Users can edit topics" do
  let(:author) { FactoryGirl.create(:user) }
  let(:forum) { FactoryGirl.create(:forum) }
  let(:topic) { FactoryGirl.create(:topic, forum: forum, author: author) }
  
  before do
    login_as(author)
    visit forum_topic_path(forum, topic)
    click_link "Edit Topic"
  end
  
  scenario "successfully" do
    fill_in "Title", with: "This is an awesome title"
    fill_in "Description", with: "dude bro do you even lift? get guud brah."
    
    click_button "Update Topic"
    
    expect(page).to have_content "Topic has been updated."
  end
end

gistfile2.txt

class TopicsController < ApplicationController
  before_action :verify_author, only: [:destroy, :update, :edit]
  before_action :authenticate_user!, only: [:create, :new]
  before_action :set_forum
  before_action :set_topic, only: [:update, :destroy, :edit, :show]
  
  def index
    @topics = Topic.all
  end
  
  def new
    @topic = @forum.topics.build
  end
  
  def show
  end
  
  def edit
  end
  
  def create
    @topic = @forum.topics.build(topic_params)
    
    @topic.author = current_user
    
    if @topic.save
      flash[:notice] = "Topic has been successfully created."
      redirect_to [@forum, @topic]
    else
      flash.now[:alert] = "Topic has not been created."
      render 'edit'
    end
  end
  
  def destroy
    @topic.destroy
    
    flash[:notice] = "Topic has been deleted."
    redirect_to @forum
  end
  
  def update
    if @topic.update(topic_params)
      flash[:notice] = "Topic has been updated."
      redirect_to [@forum, @topic]
    else
      flash.now[:alert] = "Topic has not been updated."
      render 'edit'
    end
  end
  
  private
  
  def topic_params
    params.require(:topic).permit(:title, :description)
  end
  
  def set_forum
    @forum = Forum.find(params[:forum_id])
  end
  
  def set_topic
    @topic = @forum.topics.find(params[:id])
  end
  
  def verify_author
    unless current_user.email == @topic.author.email
      flash[:alert] = 'Only the author can edit or delete their own post.'
      redirect_to forums_path
    end
  end
end

1. Users can edit topics successfully
   Failure/Error: unless current_user.email == @topic.author.email

 NoMethodError:
   undefined method `author' for nil:NilClass