Ability to clear checkout

tests.rb

@@ -35,6 +35,19 @@ class TestCheckout < Minitest::Test
     assert_equal 0.00, @checkout.total
   end
 
+  def test_that_we_can_empty_the_checkout
+    @checkout.add(:PI5)
+    @checkout.add(:ZERO2W)
+    @checkout.add(:PICO2)
+
+    refute_empty @checkout.items
+
+    @checkout.clear
+
+    assert_empty @checkout.items
+
+  end
+
   # Discounts
 
   def test_that_bogof_applied