I am failing 3 tests and I have found numerous examples on here and on on the internet in general but I can't seem to find where I'm going wrong. Thanks for any help.

1) User pages signup with valid information edit page 
 Failure/Error: before { visit edit_user_path(user) }
 ActionView::Template::Error:
   undefined method `model_name' for NilClass:Class
 # ./app/views/users/edit.html.erb:6:in  `_app_views_users_edit_html_erb___4113112884365867193_70232486166220'
 # ./spec/requests/user_pages_spec.rb:96:in `block (5 levels) in <top (required)>'

2) User pages signup with valid information edit page 
 Failure/Error: before { visit edit_user_path(user) }
 ActionView::Template::Error:
   undefined method `model_name' for NilClass:Class
 # ./app/views/users/edit.html.erb:6:in `_app_views_users_edit_html_erb___4113112884365867193_70232486166220'
 # ./spec/requests/user_pages_spec.rb:96:in `block (5 levels) in <top (required)>'

3) User pages signup with valid information edit page 
 Failure/Error: before { visit edit_user_path(user) }
 ActionView::Template::Error:
   undefined method `model_name' for NilClass:Class
 # ./app/views/users/edit.html.erb:6:in `_app_views_users_edit_html_erb___4113112884365867193_70232486166220'
 # ./spec/requests/user_pages_spec.rb:96:in `block (5 levels) in <top (required)>'

Finished in 0.26515 seconds
3 examples, 3 failures

Failed examples:

rspec ./spec/requests/user_pages_spec.rb:100 # User pages signup with valid information edit page 
rspec ./spec/requests/user_pages_spec.rb:99 # User pages signup with valid information edit page 
rspec ./spec/requests/user_pages_spec.rb:101 # User pages signup with valid information edit page 

authentication_pages_spec.rb

    require 'spec_helper'

 describe "Authentication" do

 subject { page }

 describe "signin page" do
  before { visit signin_path }

  it { should have_selector('h1',    text: 'Sign in') }
  it { should have_selector('title', text: 'Sign in') }
end

describe "signin" do
before { visit signin_path }

describe "with invalid information" do
  before { click_button "Sign in" }

  it { should have_selector('title', text: 'Sign in') }
  it { should have_selector('div.alert.alert-error', text: 'Invalid') }

  describe "after visiting another page" do
    before { click_link "Home" }
    it { should_not have_selector('div.alert.alert-error') }
  end
end

describe "with valid information" do
  let(:user) { FactoryGirl.create(:user) }
  before do
    fill_in "Email", with: user.email
    fill_in "Password", with: user.password
    click_button "Sign in"
  end



  it { should have_selector('title', text: user.name) }
  it { should have_link('Profile', href: user_path(user)) }
  it { should have_link('Sign out', href: signout_path) }
  it { should_not have_link('Sign in', href: signin_path) }

  describe "followed by signout" do
    before { click_link "Sign out" }
    it { should have_link('Sign in') }
  end
 end
end


end  

Here is the users_controller:

    class UsersController < ApplicationController

 def show
   @user = User.find(params[:id])
 end

 def new
    @user = User.new
 end

 def create
     @user = User.new(params[:user])
    if @user.save
    sign_in @user
  flash[:success] = "Welcome to the Sample App!"
  redirect_to @user
else
  render 'new'
  end
 end
end

 def edit
     @user = User.find(params[:id])
 end      

edit.html.erb:

  <% provide(:title, "Edit user") %> 
  <h1>Update your profile</h1>

<div class="row">
 <div class="span6 offset3">
  <%= form_for(@user) do |f| %>
  <%= render 'shared/error_messages' %>

  <%= f.label :name %>
  <%= f.text_field :name %>

  <%= f.label :email %>
  <%= f.text_field :email %>

  <%= f.label :password %>
  <%= f.password_field :password %>

  <%= f.label :password_confirmation, "Confirm Password" %>
  <%= f.password_field :password_confirmation %>

   <%= f.submit "Save changes", class: "btn btn-large btn-primary" %>
  <% end %>

    <%= gravatar_for @user %>
  <a href="http://gravatar.com/emails">change</a>
 </div>

here is the user_pages_spec:

    require 'spec_helper'

describe "User pages" do

subject { page }

describe "profile page" do
let(:user) { FactoryGirl.create(:user) }
before { visit user_path(user) }

it { should have_selector('h1', text: user.name) }
it { should have_selector('title', text: user.name) }
end

describe "signup page" do
 before { visit signup_path }

it { should have_selector('h1', text: 'Sign up') }
it { should have_selector('title', text: full_title('Sign up')) }
end

describe "signup" do

before { visit signup_path }

describe "with invalid information" do
it "should not create a user" do
  expect { click_button "Create my account" }.not_to change(User, :count)
end

describe "error messages" do
  before { click_button "Create my account" }

  it { should have_selector('title', text: 'Sign up') }
  it { should have_content('error') }
 end
end

 describe "with valid information" do
  before do
    fill_in "Name", with: "Example User"
    fill_in "Email", with: "[email protected]"
    fill_in "Password", with: "foobar"
    fill_in "Confirmation", with: "foobar"
 end

 it "should create a user" do
  expect do
    click_button "Create my account"
  end.to change(User, :count).by(1)
 end

 describe "after saving the user" do
  before { click_button "Create my account" }
  let(:user) { User.find_by_email('[email protected]') }

  it { should have_selector('title', text: user.name) }
  it { should have_selector('div.alert.alert-success', text: 'Welcome') }
  it { should have_link('Sign out') }
 end
 end
end

 describe "signup page" do
 before { visit signup_path }

it { should have_selector('h1', text: 'Sign up') }
it { should have_selector('title', text: full_title('Sign up')) }
end

  describe "signup" do

before { visit signup_path }

let(:submit) { "Create my account" }

describe "with invalid information" do
it "should not create a user" do
  expect { click_button submit }.not_to change(User, :count)
 end
end

describe "with valid information" do
before do
  fill_in "Name", with: "Example User"
  fill_in "Email", with: "[email protected]"
  fill_in "Password", with: "foobar"
  fill_in "Confirmation", with: "foobar"
end

it "should create a user" do
  expect { click_button submit }.to change(User, :count).by(1)
end
describe "edit" do
  let(:user) { FactoryGirl.create(:user) }
  before { visit edit_user_path(user) }

  describe "page" do
    it { should have_selector('h1', text: "Update your profile") }
    it { should have_selector('title', text: "Edit user") }
    it { should have_link('change', href: 'http://gravatar.com/emails') }
  end

  describe "with invalid information" do
    before { click_button "Save changes" }

    it { should have_content('error') }
    end
     end
     end
   end
 end

edit: users_controllers.rb was formatted incorrectly. It should look like this:

class UsersController < ApplicationController

 def show
  @user = User.find(params[:id])
 end

def new
 @user = User.new
end

def create
 @user = User.new(params[:user])
 if @user.save
  sign_in @user
  flash[:success] = "Welcome to the Sample App!"
  redirect_to @user
else
  render 'new'
 end
end

def edit
  @user = User.find(params[:id])
 end 
end