3.3 - Refusing Orders When There Are No More Tickets

app/Concert.php

@@ -3,6 +3,7 @@
 namespace App;
 
 use Illuminate\Database\Eloquent\Model;
+use App\Exceptions\NotEnoughTicketsException;
 
 class Concert extends Model
 {
@@ -41,8 +42,13 @@ class Concert extends Model
 
     public function orderTickets($email, $ticketQuantity)
     {
+        $tickets = $this->tickets()->available()->take($ticketQuantity)->get();
+
+        if ($tickets->count() < $ticketQuantity) {
+            throw new NotEnoughTicketsException;
+        }
+
         $order = $this->orders()->create(['email' => $email]);
-        $tickets = $this->tickets()->take($ticketQuantity)->get();
 
         foreach ($tickets as $ticket) {
             $order->tickets()->save($ticket);
@@ -60,6 +66,6 @@ class Concert extends Model
 
     public function ticketsRemaining()
     {
-        return $this->tickets()->whereNull('order_id')->count();
+        return $this->tickets()->available()->count();
     }
 }

app/Exceptions/NotEnoughTicketsException.php

@@ -0,0 +1,5 @@
+<?php
+
+namespace App\Exceptions;
+
+class NotEnoughTicketsException extends \RuntimeException {}

app/Ticket.php

@@ -6,5 +6,8 @@ use Illuminate\Database\Eloquent\Model;
 
 class Ticket extends Model
 {
-    //
+    public function scopeAvailable($query)
+    {
+        return $query->whereNull('order_id');
+    }
 }

tests/unit/ConcertTest.php

@@ -2,6 +2,7 @@
 
 use App\Concert;
 use Carbon\Carbon;
+use App\Exceptions\NotEnoughTicketsException;
 use Illuminate\Foundation\Testing\WithoutMiddleware;
 use Illuminate\Foundation\Testing\DatabaseMigrations;
 use Illuminate\Foundation\Testing\DatabaseTransactions;
@@ -58,6 +59,7 @@ class ConcertTest extends TestCase
     function can_order_concert_tickets()
     {
         $concert = factory(Concert::class)->create();
+        $concert->addTickets(3);
 
         $order = $concert->orderTickets('jane@example.com', 3);
 
@@ -84,4 +86,41 @@ class ConcertTest extends TestCase
 
         $this->assertEquals(20, $concert->ticketsRemaining());
     }
+
+    /** @test */
+    function trying_to_purchase_more_tickets_than_remain_throws_an_exception()
+    {
+        $concert = factory(Concert::class)->create();
+        $concert->addTickets(10);
+
+        try {
+            $concert->orderTickets('jane@example.com', 11);
+        } catch (NotEnoughTicketsException $e) {
+            $order = $concert->orders()->where('email', 'jane@example.com')->first();
+            $this->assertNull($order);
+            $this->assertEquals(10, $concert->ticketsRemaining());
+            return;
+        }
+
+        $this->fail("Order succeeded even though there were not enough tickets remaining.");
+    }
+
+    /** @test */
+    function cannot_order_tickets_that_have_already_been_purchased()
+    {
+        $concert = factory(Concert::class)->create();
+        $concert->addTickets(10);
+        $concert->orderTickets('jane@example.com', 8);
+
+        try {
+            $concert->orderTickets('john@example.com', 3);
+        } catch (NotEnoughTicketsException $e) {
+            $johnsOrder = $concert->orders()->where('email', 'john@example.com')->first();
+            $this->assertNull($johnsOrder);
+            $this->assertEquals(2, $concert->ticketsRemaining());
+            return;
+        }
+
+        $this->fail("Order succeeded even though there were not enough tickets remaining.");
+    }
 }