Add AvailableRate model

app/models/available_rate.rb

@@ -0,0 +1,5 @@
+class AvailableRate < ApplicationRecord
+  belongs_to :country
+
+  validates :rate, presence: true, uniqueness: { scope: :country_id }
+end

app/models/country.rb

@@ -1,4 +1,5 @@
 class Country < ApplicationRecord
+  has_many :available_rates, dependent: :destroy
   has_many :holidays, dependent: :destroy
 
   validates :code, presence: true, uniqueness: true

db/migrate/20240107162546_create_available_rates.rb

@@ -0,0 +1,10 @@
+class CreateAvailableRates < ActiveRecord::Migration[7.1]
+  def change
+    create_table :available_rates do |t|
+      t.timestamps null: false
+      t.references :country, null: false, foreign_key: true
+      t.string :rate
+      t.index %i[country_id rate], unique: true
+    end
+  end
+end

test/fixtures/available_rates.yml

@@ -0,0 +1,11 @@
+es_by_period:
+  country_id: 1
+  rate: "by_period"
+
+es_fixed:
+  country_id: 1
+  rate: "fixed"
+
+es_pvpc:
+  country_id: 1
+  rate: "pvpc"

test/models/available_rate_test.rb

@@ -0,0 +1,30 @@
+require "test_helper"
+
+class AvailableRateTest < ActiveSupport::TestCase
+  test "create without country" do
+    available_rate = AvailableRate.new
+
+    assert_not available_rate.save
+    assert available_rate.errors.added?(:country, :blank)
+  end
+
+  test "create without rate" do
+    available_rate = AvailableRate.new
+
+    assert_not available_rate.save
+    assert available_rate.errors.added?(:rate, :blank)
+  end
+
+  test "create with duplicate rate" do
+    available_rate = AvailableRate.new(country: countries(:es), rate: "pvpc")
+
+    assert_not available_rate.save
+    assert available_rate.errors.added?(:rate, :taken, value: "pvpc")
+  end
+
+  test "create with valid attributes" do
+    available_rate = AvailableRate.new(country: countries(:es), rate: "test")
+
+    assert available_rate.save
+  end
+end

test/models/country_test.rb

@@ -52,4 +52,8 @@ class CountryTest < ActiveSupport::TestCase
   test "associated with holidays" do
     assert_equal 16, countries(:es).holidays.count
   end
+
+  test "associated with available_rates" do
+    assert_equal 3, countries(:es).available_rates.count
+  end
 end