adding validation tests to model

app/models/role.rb

 class Role < ActiveRecord::Base
   has_and_belongs_to_many :users
+
+  validates_presence_of :name
+  validates_uniqueness_of :name
 end

test/models/role_test.rb

@@ -2,4 +2,6 @@ require 'test_helper'
 
 class RoleTest < ActiveSupport::TestCase
   should have_and_belong_to_many(:users)
+  should validate_uniqueness_of(:name)
+  should validate_presence_of(:name)
 end

test/models/user_test.rb

@@ -2,4 +2,5 @@ require 'test_helper'
 
 class UserTest < ActiveSupport::TestCase
   should have_and_belong_to_many(:roles)
+  should validate_uniqueness_of(:email)
 end