fix: quantity validation should not count current transaction

app/Http/Requests/TransactionRequest.php

@@ -39,7 +39,8 @@ class TransactionRequest extends FormRequest
                     $this->input('portfolio'),
                     $this->requestOrModelValue('symbol', 'transaction'),
                     $this->requestOrModelValue('transaction_type', 'transaction'),
-                    $this->requestOrModelValue('date', 'transaction')
+                    $this->requestOrModelValue('date', 'transaction'),
+                    $this->transaction
                 ),
             ],
             'currency' => ['required', 'exists:currencies,currency'],

app/Rules/QuantityValidationRule.php

@@ -6,8 +6,8 @@ namespace App\Rules;
 
 use App\Models\Portfolio;
 use App\Models\Transaction;
-use Illuminate\Support\Carbon;
 use Illuminate\Contracts\Validation\ValidationRule;
+use Illuminate\Support\Carbon;
 
 class QuantityValidationRule implements ValidationRule
 {
@@ -20,8 +20,9 @@ class QuantityValidationRule implements ValidationRule
         protected ?Portfolio $portfolio,
         protected ?string $symbol,
         protected ?string $transactionType,
-        protected string|Carbon|null $date
-    ) { }
+        protected string|Carbon|null $date,
+        protected ?Transaction $transaction
+    ) {}
 
     /**
      * Validate the attribute.
@@ -42,6 +43,7 @@ class QuantityValidationRule implements ValidationRule
                 ->sum('quantity');
 
             $sales_qty = (float) $this->portfolio->transactions()
+                ->where('id', '!=', $this->transaction?->id)
                 ->symbol($this->symbol)
                 ->sell()
                 ->whereDate('date', '<', $this->date)

database/factories/TransactionFactory.php

@@ -122,19 +122,21 @@ class TransactionFactory extends Factory
         ]);
     }
 
-    public function buy(): static
+    public function buy($quantity = 1): static
     {
         return $this->state(fn (array $attributes) => [
             'transaction_type' => 'BUY',
+            'quantity' => $quantity,
             'cost_basis' => $this->faker->randomFloat(2, 10, 500),
             'sale_price' => null,
         ]);
     }
 
-    public function sell(): static
+    public function sell($quantity = 1): static
     {
         return $this->state(fn (array $attributes) => [
             'transaction_type' => 'SELL',
+            'quantity' => $quantity,
             'sale_price' => $this->faker->randomFloat(2, 10, 500),
             'cost_basis' => null,
         ]);

resources/views/transaction/manage-transaction-form.blade.php

@@ -19,7 +19,7 @@ new class extends Component
     // props
     public ?Portfolio $portfolio;
 
-    public ?Transaction $transaction;
+    public ?Transaction $transaction = null;
 
     public ?string $portfolio_id;
 
@@ -53,7 +53,7 @@ new class extends Component
                 'required',
                 'numeric',
                 'gt:0',
-                new QuantityValidationRule($this->portfolio, $this->symbol, $this->transaction_type, $this->date),
+                new QuantityValidationRule($this->portfolio, $this->symbol, $this->transaction_type, $this->date, $this->transaction),
             ],
             'currency' => ['required', 'exists:currencies,currency'],
             'cost_basis' => 'exclude_if:transaction_type,SELL|min:0|numeric',

tests/Api/TransactionsTest.php

@@ -114,6 +114,35 @@ class TransactionsTest extends TestCase
             ->assertJsonValidationErrors(['symbol']);
     }
 
+    public function test_cannot_sell_more_than_owned()
+    {
+        Artisan::call('db:seed', [
+            '--class' => CurrencySeeder::class,
+            '--force' => true,
+        ]);
+
+        $this->actingAs($this->user);
+
+        $portfolio = Portfolio::factory()->create();
+
+        Transaction::factory(5)->buy()->lastYear()->portfolio($portfolio->id)->symbol('AAPL')->create();
+
+        $data = [
+            'symbol' => 'AAPL',
+            'portfolio_id' => $this->portfolio->id,
+            'transaction_type' => 'SELL',
+            'quantity' => 6,
+            'currency' => 'USD',
+            'date' => now()->toDateString(),
+            'sale_price' => 150,
+        ];
+
+        $this->actingAs($this->user)
+            ->postJson(route('api.transaction.store'), $data)
+            ->assertUnprocessable()
+            ->assertJsonValidationErrors(['quantity']);
+    }
+
     public function test_can_show_a_transaction()
     {
         $this->actingAs($this->user);

tests/TransactionsTest.php

@@ -8,6 +8,7 @@ use App\Models\Holding;
 use App\Models\Portfolio;
 use App\Models\Transaction;
 use App\Models\User;
+use App\Rules\QuantityValidationRule;
 use Illuminate\Foundation\Testing\RefreshDatabase;
 
 class TransactionsTest extends TestCase
@@ -69,4 +70,22 @@ class TransactionsTest extends TestCase
             0.01
         );
     }
+
+    public function test_cannot_sell_more_than_owned(): void
+    {
+        $this->actingAs($user = User::factory()->create());
+
+        $portfolio = Portfolio::factory()->create();
+
+        Transaction::factory(5)->buy()->lastYear()->portfolio($portfolio->id)->symbol('AAPL')->create();
+        $sale_transaction = Transaction::factory()->sell(6)->lastMonth()->portfolio($portfolio->id)->symbol('AAPL')->make();
+
+        $rule = new QuantityValidationRule($portfolio, $sale_transaction->symbol, 'SELL', $sale_transaction->date, $sale_transaction);
+
+        $rule->validate('quantity', $sale_transaction->quantity, function () {
+            $this->assertFalse(false, 'Not permitted to sell more than owned.');
+        });
+
+        $this->assertTrue(true);
+    }
 }