add zone test-rspec

app/models/seat_table.rb

@@ -1,3 +1,6 @@
 class SeatTable < ApplicationRecord
   belongs_to :zone
+
+  # validations
+  validates_presence_of :name,:order_by, :created_by
 end

app/models/zone.rb

@@ -1,2 +1,7 @@
 class Zone < ApplicationRecord
+  # model association
+ has_many :seat_tables, dependent: :destroy
+
+ # validations
+ validates_presence_of :name, :created_by
 end