fix school year for all tables

tests/app/Libraries/InvoiceLedgerServiceTest.php

@@ -0,0 +1,91 @@
+<?php
+
+namespace Tests\App\Libraries;
+
+use App\Libraries\FinancialStatus;
+use App\Libraries\InvoiceLedgerService;
+use CodeIgniter\Test\CIUnitTestCase;
+
+class InvoiceLedgerServiceHarness extends InvoiceLedgerService
+{
+    private array $invoice;
+    private float $paidTotal;
+
+    public function __construct(array $invoice, float $paidTotal = 0.0)
+    {
+        $this->invoice = $invoice;
+        $this->paidTotal = $paidTotal;
+    }
+
+    protected function loadInvoice(int $invoiceId): ?array
+    {
+        return $invoiceId === (int) ($this->invoice['id'] ?? 0) ? $this->invoice : null;
+    }
+
+    protected function calculateTuitionTotal(array $invoice): float
+    {
+        return 0.0;
+    }
+
+    protected function calculateEventTotal(array $invoice): float
+    {
+        return 0.0;
+    }
+
+    protected function calculateAdditionalCharges(int $invoiceId): float
+    {
+        return 0.0;
+    }
+
+    protected function calculateDiscounts(int $invoiceId): float
+    {
+        return 0.0;
+    }
+
+    protected function calculateValidPayments(int $invoiceId): float
+    {
+        return $this->paidTotal;
+    }
+
+    protected function calculatePaidRefunds(int $invoiceId): float
+    {
+        return 0.0;
+    }
+}
+
+class InvoiceLedgerServiceTest extends CIUnitTestCase
+{
+    public function testCarryForwardInvoiceUsesStoredOpeningBalance(): void
+    {
+        $service = new InvoiceLedgerServiceHarness([
+            'id' => 10,
+            'invoice_number' => 'CF-20252026-20262027-P8-I4',
+            'total_amount' => '90.00',
+            'semester' => 'Opening Balance',
+            'description' => 'Balance carried over from previous school year 2025-2026.',
+        ]);
+
+        $calculation = $service->calculateInvoice(10);
+
+        $this->assertSame('90.00', $calculation['total_amount']);
+        $this->assertSame('90.00', $calculation['balance']);
+        $this->assertSame(FinancialStatus::INVOICE_UNPAID, $calculation['status']);
+    }
+
+    public function testCarryForwardInvoiceIsPaidAfterFullPayment(): void
+    {
+        $service = new InvoiceLedgerServiceHarness([
+            'id' => 10,
+            'invoice_number' => 'CF-20252026-20262027-P8-I4',
+            'total_amount' => '90.00',
+            'semester' => 'Opening Balance',
+            'description' => 'Balance carried over from previous school year 2025-2026.',
+        ], 90.0);
+
+        $calculation = $service->calculateInvoice(10);
+
+        $this->assertSame('90.00', $calculation['total_amount']);
+        $this->assertSame('0.00', $calculation['balance']);
+        $this->assertSame(FinancialStatus::INVOICE_PAID, $calculation['status']);
+    }
+}