diff --git a/app/Cart/CartCollection.php b/app/Cart/CartCollection.php
index ad93954..5763431 100644
--- a/app/Cart/CartCollection.php
+++ b/app/Cart/CartCollection.php
@@ -52,6 +52,19 @@ class CartCollection
         return null;
     }
 
+    public function updateDraftAttributes($draftKey, $draftAttributes)
+    {
+        $content = $this->getContent();
+
+        foreach ($draftAttributes as $attribute => $value) {
+            $content[$draftKey]->{$attribute} = $value;
+        }
+
+        $this->session->put($this->instance, $content);
+
+        return $content[$draftKey];
+    }
+
     public function removeDraft($draftKey)
     {
         $content = $this->getContent();
@@ -85,39 +98,28 @@ class CartCollection
         $this->session->remove($this->instance);
     }
 
-    public function addItemToCart($draftKey, $item)
+    public function addProductToDraft($draftKey, $item)
     {
         $content = $this->getContent();
-        $content[$draftKey]->addItem($item);
-        $content[$draftKey] = $this->updateCart($content[$draftKey]);
+        $content[$draftKey]->addProduct($item);
+        $content[$draftKey] = $this->updateDraft($content[$draftKey]);
 
         $this->session->put($this->instance, $content);
     }
 
-    public function updateCart(Cart $draft)
-    {
-        $draft->charged_weight = $draft->getChargedWeight();
-        $draft->items_count = $draft->itemsCount();
-        $draft->pcs_count = $draft->itemsCount();
-        $draft->base_charge = $draft->getCharge();
-        $draft->subtotal = $draft->getCharge();
-        $draft->total = $draft->getCharge();
-        return $draft;
-    }
-
-    public function updateCartItem($draftKey, $itemKey, $newItemData)
+    public function updateDraftProduct($draftKey, $itemKey, $newProductData)
     {
         $content = $this->getContent();
-        $content[$draftKey]->updateItem($itemKey, $newItemData);
-        $content[$draftKey] = $this->updateCart($content[$draftKey]);
+        $content[$draftKey]->updateProduct($itemKey, $newProductData);
+        $content[$draftKey] = $this->updateDraft($content[$draftKey]);
 
         $this->session->put($this->instance, $content);
     }
 
-    public function removeItemFromCart($draftKey, $itemKey)
+    public function removeProductFromDraft($draftKey, $itemKey)
     {
         $content = $this->getContent();
-        $content[$draftKey]->removeItem($itemKey);
+        $content[$draftKey]->removeProduct($itemKey);
 
         $this->session->put($this->instance, $content);
     }
diff --git a/app/Cart/CashDraft.php b/app/Cart/CashDraft.php
index 54d0f47..2d774f5 100644
--- a/app/Cart/CashDraft.php
+++ b/app/Cart/CashDraft.php
@@ -5,7 +5,7 @@ namespace App\Cart;
 /**
 * Cash Draft
 */
-class CashDraft implements TransactionDraft
+class CashDraft extends TransactionDraft
 {
     public $draftKey;
 }
\ No newline at end of file
diff --git a/app/Cart/CreditDraft.php b/app/Cart/CreditDraft.php
index d5876d2..7777af6 100644
--- a/app/Cart/CreditDraft.php
+++ b/app/Cart/CreditDraft.php
@@ -5,7 +5,7 @@ namespace App\Cart;
 /**
 * Credit Draft
 */
-class CreditDraft implements TransactionDraft
+class CreditDraft extends TransactionDraft
 {
     public $draftKey;
 }
\ No newline at end of file
diff --git a/app/Cart/TransactionDraft.php b/app/Cart/TransactionDraft.php
index caf364b..7d33cf0 100644
--- a/app/Cart/TransactionDraft.php
+++ b/app/Cart/TransactionDraft.php
@@ -5,4 +5,20 @@ namespace App\Cart;
 /**
 * Transaction Draft Interface
 */
-interface TransactionDraft {}
\ No newline at end of file
+abstract class TransactionDraft
+{
+    public function toArray()
+    {
+        return [
+            'invoice_no' => 2,
+            'date'       => 1,
+            'items'      => [],
+            'total'      => 0,
+            'payment'    => 0,
+            'customer'   => 0,
+            'status_id'  => 0,
+            'creator_id' => 0,
+            'remark'     => '',
+        ];
+    }
+}
\ No newline at end of file
diff --git a/tests/Unit/CartCollectionTest.php b/tests/Unit/CartCollectionTest.php
index e496c7e..5f22add 100644
--- a/tests/Unit/CartCollectionTest.php
+++ b/tests/Unit/CartCollectionTest.php
@@ -97,4 +97,52 @@ class CartCollectionTest extends TestCase
         $this->assertCount(0, $cart->content());
         $this->assertTrue($cart->isEmpty());
     }
+
+    /** @test */
+    public function it_has_content_keys()
+    {
+        $cart = new CartCollection;
+
+        $cashDraft = new CashDraft;
+        $creditDraft = new CreditDraft;
+
+        $cart->add($cashDraft);
+        $cart->add($creditDraft);
+
+        $this->assertCount(2, $cart->keys());
+        $cart->removeDraft($cart->content()->keys()->last());
+        $this->assertCount(1, $cart->keys());
+    }
+
+    /** @test */
+    public function it_can_update_a_draft_attributes()
+    {
+        $cart = new CartCollection;
+
+        $draft = $cart->add(new CashDraft);
+        $this->assertCount(1, $cart->content());
+
+        $newDraftAttribute = [
+            'invoice_no' => 2,
+            'date'       => 1,
+            'items'      => [],
+            'total'      => 0,
+            'payment'    => 0,
+            'customer'   => 0,
+            'status_id'  => 0,
+            'creator_id' => 0,
+            'remark'     => 0,
+        ];
+
+        $cart->updateDraftAttributes($draft->draftKey, $newDraftAttribute);
+        $this->assertArrayHasKey('invoice_no', $draft->toArray());
+        $this->assertArrayHasKey('date', $draft->toArray());
+        $this->assertArrayHasKey('items', $draft->toArray());
+        $this->assertArrayHasKey('total', $draft->toArray());
+        $this->assertArrayHasKey('payment', $draft->toArray());
+        $this->assertArrayHasKey('customer', $draft->toArray());
+        $this->assertArrayHasKey('status_id', $draft->toArray());
+        $this->assertArrayHasKey('creator_id', $draft->toArray());
+        $this->assertArrayHasKey('remark', $draft->toArray());
+    }
 }