Add park <-> alert relations

app/models/alert.rb

@@ -1,2 +1,4 @@
 class Alert < ApplicationRecord
+  belongs_to :park, foreign_key: :park_code, primary_key: :code,
+    inverse_of: :alerts
 end

app/models/park.rb

@@ -1,2 +1,4 @@
 class Park < ApplicationRecord
+  has_many :alerts, foreign_key: :park_code, primary_key: :code,
+    inverse_of: :park, dependent: :destroy
 end

spec/models/alert_spec.rb

@@ -1,5 +1,9 @@
 require 'rails_helper'
 
 RSpec.describe Alert, type: :model do
-  pending "add some examples to (or delete) #{__FILE__}"
+  describe "#park" do
+    it "has a park" do
+      expect(alerts(:one).park).to eq(parks(:one))
+    end
+  end
 end