Validate and enforce AdjustmentMetadata associations

app/models/adjustment_metadata.rb

@@ -1,6 +1,8 @@
 # frozen_string_literal: true
 
 class AdjustmentMetadata < ApplicationRecord
+  self.belongs_to_required_by_default = true
+
   belongs_to :adjustment, class_name: 'Spree::Adjustment'
   belongs_to :enterprise
 end

db/migrate/20230503060530_require_adjustment_and_enterprise_on_adjustment_metadata.rb

@@ -0,0 +1,8 @@
+# frozen_string_literal: true
+
+class RequireAdjustmentAndEnterpriseOnAdjustmentMetadata < ActiveRecord::Migration[7.0]
+  def change
+    change_column_null :adjustment_metadata, :adjustment_id, false
+    change_column_null :adjustment_metadata, :enterprise_id, false
+  end
+end

db/schema.rb

@@ -44,8 +44,8 @@ ActiveRecord::Schema[7.0].define(version: 2023_05_22_120633) do
   end
 
   create_table "adjustment_metadata", id: :serial, force: :cascade do |t|
-    t.integer "adjustment_id"
-    t.integer "enterprise_id"
+    t.integer "adjustment_id", null: false
+    t.integer "enterprise_id", null: false
     t.string "fee_name", limit: 255
     t.string "fee_type", limit: 255
     t.string "enterprise_role", limit: 255

spec/models/adjustment_metadata_spec.rb

@@ -3,6 +3,9 @@
 require 'spec_helper'
 
 describe AdjustmentMetadata do
+  it { is_expected.to belong_to(:adjustment).required }
+  it { is_expected.to belong_to(:enterprise).required }
+
   it "is valid when built from factory" do
     adjustment_metadata = build(:adjustment_metadata)
     expect(adjustment_metadata).to be_valid