fix object_type validation

app/models/object_type.rb

 class ObjectType < ActiveRecord::Base
   has_many :learning_objects
 
-  validates :name, presence: true
+  validates_presence_of :name
+  validates_uniqueness_of :name
 end

test/fixtures/management/object_types.yml

-# Read about fixtures at http://api.rubyonrails.org/classes/ActiveRecord/FixtureSet.html
-
-# This model initially had no columns defined.  If you add columns to the
-# model remove the '{}' from the fixture names and add the columns immediately
-# below each fixture, per the syntax in the comments below
-#
-one: {}
-# column: value
-#
-two: {}
-#  column: value

test/models/management/object_type_test.rb

-require 'test_helper'
-
-class Management::ObjectTypeTest < ActiveSupport::TestCase
-  # test "the truth" do
-  #   assert true
-  # end
-end

test/models/object_type_test.rb

+require 'test_helper'
+
+class ObjectTypeTest < ActiveSupport::TestCase
+  should have_many :learning_objects
+
+  should validate_presence_of(:name)
+  should validate_uniqueness_of(:name)
+end