diff --git a/app/Billing/Charge.php b/app/Billing/Charge.php
new file mode 100644
index 0000000..140db4d
--- /dev/null
+++ b/app/Billing/Charge.php
@@ -0,0 +1,23 @@
+<?php
+
+namespace App\Billing;
+
+class Charge
+{
+    private $data;
+
+    public function __construct($data)
+    {
+        $this->data = $data;
+    }
+
+    public function amount()
+    {
+        return $this->data['amount'];
+    }
+
+    public function cardLastFour()
+    {
+        return $this->data['card_last_four'];
+    }
+}
diff --git a/app/Billing/FakePaymentGateway.php b/app/Billing/FakePaymentGateway.php
index c53b432..2a87ddb 100644
--- a/app/Billing/FakePaymentGateway.php
+++ b/app/Billing/FakePaymentGateway.php
@@ -5,16 +5,20 @@ namespace App\Billing;
 class FakePaymentGateway implements PaymentGateway
 {
     private $charges;
+    private $tokens;
     private $beforeFirstChargeCallback;
 
     public function __construct()
     {
         $this->charges = collect();
+        $this->tokens = collect();
     }
 
-    public function getValidTestToken()
+    public function getValidTestToken($cardNumber = '4242424242424242')
     {
-        return "valid-token";
+        $token = 'fake-tok_'.str_random(24);
+        $this->tokens[$token] = $cardNumber;
+        return $token;
     }
 
     public function charge($amount, $token)
@@ -25,10 +29,14 @@ class FakePaymentGateway implements PaymentGateway
             $callback($this);
         }
 
-        if ($token !== $this->getValidTestToken()) {
+        if (! $this->tokens->has($token)) {
             throw new PaymentFailedException;
         }
-        $this->charges[] = $amount;
+
+        return $this->charges[] = new Charge([
+            'amount' => $amount,
+            'card_last_four' => substr($this->tokens[$token], -4),
+        ]);
     }
 
     public function newChargesDuring($callback)
@@ -40,7 +48,7 @@ class FakePaymentGateway implements PaymentGateway
 
     public function totalCharges()
     {
-        return $this->charges->sum();
+        return $this->charges->map->amount()->sum();
     }
 
     public function beforeFirstCharge($callback)
diff --git a/database/migrations/2016_11_08_205823_create_orders_table.php b/database/migrations/2016_11_08_205823_create_orders_table.php
index 803a78f..d51b725 100644
--- a/database/migrations/2016_11_08_205823_create_orders_table.php
+++ b/database/migrations/2016_11_08_205823_create_orders_table.php
@@ -15,7 +15,7 @@ class CreateOrdersTable extends Migration
     {
         Schema::create('orders', function (Blueprint $table) {
             $table->increments('id');
-            $table->string('confirmation_number')->nullable();
+            $table->string('confirmation_number');
             $table->integer('amount');
             $table->string('email');
             $table->string('card_last_four')->nullable();
diff --git a/tests/unit/Billing/PaymentGatewayContractTests.php b/tests/unit/Billing/PaymentGatewayContractTests.php
index 04025db..62bde6c 100644
--- a/tests/unit/Billing/PaymentGatewayContractTests.php
+++ b/tests/unit/Billing/PaymentGatewayContractTests.php
@@ -16,7 +16,18 @@ trait PaymentGatewayContractTests
         });
 
         $this->assertCount(1, $newCharges);
-        $this->assertEquals(2500, $newCharges->sum());
+        $this->assertEquals(2500, $newCharges->map->amount()->sum());
+    }
+
+    /** @test */
+    function can_get_details_about_a_successful_charge()
+    {
+        $paymentGateway = $this->getPaymentGateway();
+
+        $charge = $paymentGateway->charge(2500, $paymentGateway->getValidTestToken('0000000000004242'));
+
+        $this->assertEquals('4242', $charge->cardLastFour());
+        $this->assertEquals(2500, $charge->amount());
     }
 
     /** @test */
@@ -50,6 +61,6 @@ trait PaymentGatewayContractTests
         });
 
         $this->assertCount(2, $newCharges);
-        $this->assertEquals([5000, 4000], $newCharges->all());
+        $this->assertEquals([5000, 4000], $newCharges->map->amount()->all());
     }
 }