Rails Testing

item.rb

class Item < ActiveRecord::Base
  validates :name, presence: true
end

item_test.rb

require 'test_helper'

class ItemTest < ActiveSupport::TestCase
  test 'it creates an item' do
    item = Item.create(name: 'hat', description: 'this is a hat', price: 10)

    assert_equal 'hat',           item.name
    assert_equal 'this is a hat', item.description
    assert_equal 10,              item.price
  end

  test 'it cannot create an item without a name' do
    item = Item.new(description: 'this is a hat', price: 10)

    refute item.valid?, 'Expected to be invalid, but was valid.'
  end
end

items_controller.rb

class ItemsController < ApplicationController
  def show
    @item = Item.find(params[:id])
  end

  def index
    @items = Item.all
  end
end

items_controller_test.rb

require 'test_helper'

class ItemsControllerTest < ActionController::TestCase
  test '#show' do
    item = Item.create(name: 'hat', description: 'this is a hat', price: 100)

    get :show, id: item.id

    assert_response :success
    assert_not_nil assigns(:item)
  end

  test '#index' do
    item_1 = Item.create(name: 'glass', description: 'this is a glass', price: 100)
    item_2 = Item.create(name: 'hat', description: 'this is a hat', price: 100)

    get :index

    assert_response :success
    assert_not_nil assigns(:items)
  end
end