added simplecov and a new test

+ simplecov is a test coverage tool to show what code is covered and
  where holes are
+ added newest test to validate that the redirect url works as expected

features/homepage.feature

@@ -33,3 +33,9 @@ Feature: Homepage
     And I click the "Submit" button
     Then I should be on "/create" page
     And I should see the message "Link exists"
+
+  @db-test
+  Scenario: Accessing the URL based on the shortcode
+    Given A link already exists with the url "https://google.com" and code "aaaaaa"
+    When I visit the "/aaaaaa" location
+    Then I should be redirected to "https://google.com"

features/step_definitions/steps.rb

@@ -13,6 +13,10 @@ Given('A link already exists with the url {string}') do |string|
   @links.insert(url: string, code: "aaaaaa")
 end
 
+Given('A link already exists with the url {string} and code {string}') do |url, code|
+  @links.insert(url: url, code: code)
+end
+
 # WHEN
 
 When('I click the {string} button') do |string|
@@ -23,6 +27,10 @@ When('I type {string} in the {string} field') do |text, field|
   fill_in field, with: text
 end
 
+When('I visit the {string} location') do |string|
+  visit string
+end
+
 # THEN
 
 Then('I should see text {string}') do |string|
@@ -45,6 +53,11 @@ Then('I should see the message {string}') do |message|
   page.should have_selector '#message', text: message
 end
 
+Then('I should be redirected to {string}') do |string|
+  actual = URI.parse(current_url).to_s
+  location = actual.index(string)
+  location.should equal(0)
+end
 # AFTER
 
 After('@db-test') do

features/support/env.rb

@@ -1,3 +1,6 @@
+require 'simplecov'
+SimpleCov.start
+
 require_relative '../../.env'
 ENV["DB_NAME"] = "test_#{ENV["DB_NAME"]}"
 require_relative '../../app'