Ruby on Rails

I have

app/controllers/admin/post_categories_controller.rb
app/models/post_category
app/test/controllers/admin/post_categories_controller_test.rb

When I run

rake test app/test/controllers/admin/post_categories_controller.rb`

I get errors like:

  1) Error:

PostCategoryTest#test_should_not_save_post_category_without_title:

ActiveRecord::StatementInvalid: PG::UndefinedTable: ERROR:  relation "admin_post_categories" does not exist

LINE 1: DELETE FROM "admin_post_categories"

Here's part of my `post_categories_controller_test.rb`:

require 'test_helper'

class Admin::PostCategoriesControllerTest < ActionController::TestCase

  setup do

    @post_category = post_categories(:one)

  end

  test "should get index" do

    get :index

    assert_response :success

    assert_not_nil assigns(:post_categories)

  end

  test "should get new" do

    get :new

    assert_response :success

  end

So, basically my problem is that controllers, views and other things are namespaced (for now there is an "admin" namespace, but I will also add a "public" namespace later), but I want to use the same models (not namespaced models) for both the admin and the public area of this system.

Thanks in advance for any help.