ActionController::UrlGenerationError: No route matches {:action=>"edit", :controller=>"posts"} - rake test fails but app works correctly

When I run my rake test it comes up with two errors. However, when I run my blog, the index, show, new, and edit views all work correctly and do not generate errors in the browser. How do my tests fail but my blog doesn't? I've looked through other answers on this topic but most seem to do with links or nested elements in methods. I have neither.

1) Error:
PostsControllerTest#test_should_get_edit:
ActionController::UrlGenerationError: No route matches {:action=>"edit", :controller=>"posts"}
test/controllers/posts_controller_test.rb:25:in `block in <class:PostsControllerTest>'


2) Error:
PostsControllerTest#test_should_get_show:
ActionController::UrlGenerationError: No route matches {:action=>"show", :controller=>"posts"}
test/controllers/posts_controller_test.rb:15:in `block in <class:PostsControllerTest>'

Here is my show.html.erb

<h1><%= @post.title %></h1>
<h3> Posted: <%= @post.created_at.strftime("%I:%M %p") %> by Tarrence</h3>
<p><%= @post.body %></p>

</div>
<%= render 'sidebar' %>

Here is my edit.html.erb

<h1>Edit</h1>
<%= render 'form' %>
</div>

Here is my _form.html.erb

<%= form_for(@post) do |f| %>
  <%= f.label :title %>
  <%= f.text_field :title, class: "form-control" %>

  <%= f.label :topic %>
  <%= f.text_field :topic, class: "form-control" %>

  <%= f.label :body %>
  <%= f.text_area :body, class: "form-control" %>

  <%= f.submit "Post", class: "btn btn-primary submit" %>
<% end %>

Here is my index.html.erb

<div class="blog-post">
        <% @posts.each do |post| %>
            <h3><%= post.title %></h3>
            <span>Posted by Tarrence <%= post.created_at.strftime("at %I:%M %p") %></span><br>
            <span>Topic: <%= post.topic %></span>

            <% if post.body.length > 100 %>
                <p><%= truncate(post.body, length: 100, separator: ' ') %>
                <%= link_to "Read More", post_path(post) %></p>
            <% else %>
                <p><%= post.body %></p>
            <% end %>

            <hr>
        <% end %>

    </div>

    <nav class="pager">
        <%= will_paginate @posts %>
    </nav>


</div>

Here is my routes.rb

root 'posts#index'
#get 'post' => 'posts#show'
#get 'post/edit' => 'posts#edit'
resources :posts

Here is my posts_controller.rb

class PostsController < ApplicationController
  def index
   # @posts = Post.all
   @posts = Post.paginate(:page => params[:page], :per_page => 2)
  end

  def show
    @post = Post.find(params[:id])
  end

  def new
    @post = Post.new
  end

  def create
    logger.info "---params ==> #{params.inspect}---"
    @post = Post.new(post_params)
    if @post.save
      redirect_to root_path
    else
      render 'new'
    end
  end

  def edit
    @post = Post.find(params[:id])
  end

  def update
    @post = Post.find(params[:id])
    if @post.update_attributes(post_params)
      redirect_to post_path(@post)
    else
      render 'edit'
    end
  end

  def destroy
  end

  private 

    def post_params
      params.require(:post).permit(:title, :topic, :body)
    end
end