feat(migrations): implement backfill for legacy refunds and add migration tests

tests/Feature/Migrations/RemoveRefundedAmountFromPurchaseItemsTest.php

@@ -0,0 +1,151 @@
+<?php
+
+namespace Tests\Feature\Migrations;
+
+use Illuminate\Database\Schema\Blueprint;
+use Illuminate\Support\Facades\DB;
+use Illuminate\Support\Facades\Schema;
+use RuntimeException;
+use Tests\TestCase;
+
+class RemoveRefundedAmountFromPurchaseItemsTest extends TestCase
+{
+    private string $originalConnection;
+
+    protected function setUp(): void
+    {
+        parent::setUp();
+
+        $this->originalConnection = DB::getDefaultConnection();
+        config()->set('database.connections.refund_migration_test', [
+            'driver' => 'sqlite',
+            'database' => ':memory:',
+            'prefix' => '',
+            'foreign_key_constraints' => true,
+        ]);
+        DB::setDefaultConnection('refund_migration_test');
+
+        Schema::create('compra_items', function (Blueprint $table): void {
+            $table->id();
+            $table->decimal('precio_unitario', 10, 2);
+            $table->decimal('total', 10, 2);
+            $table->decimal('refunded_amount', 10, 2)->default(0);
+        });
+        Schema::create('tickets', function (Blueprint $table): void {
+            $table->id();
+            $table->foreignId('source_purchase_item_id')->nullable();
+            $table->dateTime('refunded_at')->nullable();
+        });
+        Schema::create('ticket_refunds', function (Blueprint $table): void {
+            $table->id();
+            $table->foreignId('ticket_id')->unique();
+            $table->foreignId('purchase_item_id');
+            $table->foreignId('created_by_user_id')->nullable();
+            $table->string('type', 16);
+            $table->decimal('amount', 10, 2);
+            $table->timestamps();
+        });
+    }
+
+    protected function tearDown(): void
+    {
+        DB::purge('refund_migration_test');
+        DB::setDefaultConnection($this->originalConnection);
+
+        parent::tearDown();
+    }
+
+    public function test_it_backfills_a_refund_created_before_ticket_refunds_existed(): void
+    {
+        DB::table('compra_items')->insert([
+            'id' => 254,
+            'precio_unitario' => '100.00',
+            'total' => '100.00',
+            'refunded_amount' => '40.00',
+        ]);
+        DB::table('tickets')->insert([
+            'id' => 501,
+            'source_purchase_item_id' => 254,
+            'refunded_at' => '2026-09-13 18:30:00',
+        ]);
+
+        $this->migration()->up();
+
+        $this->assertFalse(Schema::hasColumn('compra_items', 'refunded_amount'));
+        $this->assertDatabaseHas('ticket_refunds', [
+            'ticket_id' => 501,
+            'purchase_item_id' => 254,
+            'created_by_user_id' => null,
+            'type' => 'partial',
+            'amount' => 40,
+            'created_at' => '2026-09-13 18:30:00',
+        ]);
+    }
+
+    public function test_it_only_backfills_the_amount_not_already_in_ticket_refunds(): void
+    {
+        DB::table('compra_items')->insert([
+            'id' => 254,
+            'precio_unitario' => '100.00',
+            'total' => '200.00',
+            'refunded_amount' => '140.00',
+        ]);
+        DB::table('tickets')->insert([
+            [
+                'id' => 501,
+                'source_purchase_item_id' => 254,
+                'refunded_at' => '2026-09-13 18:30:00',
+            ],
+            [
+                'id' => 502,
+                'source_purchase_item_id' => 254,
+                'refunded_at' => '2026-09-14 10:00:00',
+            ],
+        ]);
+        DB::table('ticket_refunds')->insert([
+            'ticket_id' => 502,
+            'purchase_item_id' => 254,
+            'created_by_user_id' => 7,
+            'type' => 'total',
+            'amount' => '100.00',
+            'created_at' => '2026-09-14 10:00:00',
+            'updated_at' => '2026-09-14 10:00:00',
+        ]);
+
+        $this->migration()->up();
+
+        $this->assertDatabaseHas('ticket_refunds', [
+            'ticket_id' => 501,
+            'purchase_item_id' => 254,
+            'created_by_user_id' => null,
+            'type' => 'partial',
+            'amount' => 40,
+        ]);
+        $this->assertSame(2, DB::table('ticket_refunds')->count());
+    }
+
+    public function test_it_still_refuses_to_drop_an_amount_without_a_refunded_ticket(): void
+    {
+        DB::table('compra_items')->insert([
+            'id' => 254,
+            'precio_unitario' => '100.00',
+            'total' => '100.00',
+            'refunded_amount' => '40.00',
+        ]);
+
+        try {
+            $this->migration()->up();
+            $this->fail('The migration should preserve an amount that cannot be backfilled.');
+        } catch (RuntimeException $exception) {
+            $this->assertStringContainsString('ítem 254', $exception->getMessage());
+            $this->assertTrue(Schema::hasColumn('compra_items', 'refunded_amount'));
+        }
+    }
+
+    private function migration(): object
+    {
+        return require database_path(
+            'migrations/2026_09_14_040000_remove_refunded_amount_from_purchase_items.php'
+        );
+    }
+}