Bring tax category factory from spree_core and fix a problem with the stock location of the product factory

spec/factories.rb

@@ -1,6 +1,7 @@
 require 'ffaker'
 
 FactoryBot.define do
+  sequence(:random_string)      { Faker::Lorem.sentence }
   sequence(:random_description) { Faker::Lorem.paragraphs(1 + Kernel.rand(5)).join("\n") }
   sequence(:random_email)       { Faker::Internet.email }
 

spec/factories/product_factory.rb

@@ -21,7 +21,7 @@ FactoryBot.define do
     shipping_category { DefaultShippingCategory.find_or_create }
 
     # ensure stock item will be created for this products master
-    before(:create) { create(:stock_location) if Spree::StockLocation.count == 0 }
+    before(:create) { DefaultStockLocation.find_or_create }
 
     factory :product do
       transient do

spec/factories/tax_category_factory.rb

@@ -0,0 +1,6 @@
+FactoryBot.define do
+  factory :tax_category, class: Spree::TaxCategory do
+    name { "TaxCategory - #{rand(999999)}" }
+    description { generate(:random_string) }
+  end
+end