create dashboard controller and update root route to it.

app/assets/javascripts/dashboard.coffee

@@ -0,0 +1,3 @@
+# Place all the behaviors and hooks related to the matching controller here.
+# All this logic will automatically be available in application.js.
+# You can use CoffeeScript in this file: http://coffeescript.org/

app/assets/stylesheets/dashboard.scss

@@ -0,0 +1,3 @@
+// Place all the styles related to the Dashboard controller here.
+// They will automatically be included in application.css.
+// You can use Sass (SCSS) here: http://sass-lang.com/

app/controllers/dashboard_controller.rb

@@ -0,0 +1,4 @@
+class DashboardController < ApplicationController
+  def index
+  end
+end

app/helpers/dashboard_helper.rb

@@ -0,0 +1,2 @@
+module DashboardHelper
+end

app/views/dashboard/index.html.erb

@@ -0,0 +1,2 @@
+<h1>Dashboard#index</h1>
+<p>Find me in app/views/dashboard/index.html.erb</p>

config/routes.rb

@@ -1,9 +1,11 @@
 Rails.application.routes.draw do
+  get 'dashboard/index'
+
   # The priority is based upon order of creation: first created -> highest priority.
   # See how all your routes lay out with "rake routes".
 
   # You can have the root of your site routed with "root"
-  # root 'welcome#index'
+  root 'dashboard#index'
 
   # Example of regular route:
   #   get 'products/:id' => 'catalog#view'

test/controllers/dashboard_controller_test.rb

@@ -0,0 +1,9 @@
+require 'test_helper'
+
+class DashboardControllerTest < ActionController::TestCase
+  test "should get index" do
+    get :index
+    assert_response :success
+  end
+
+end