diff --git a/src/main/java/org/springframework/samples/petclinic/proxy/CashPerf.java b/src/main/java/org/springframework/samples/petclinic/proxy/CashPerf.java
new file mode 100644
index 000000000..d8565f89c
--- /dev/null
+++ b/src/main/java/org/springframework/samples/petclinic/proxy/CashPerf.java
@@ -0,0 +1,18 @@
+package org.springframework.samples.petclinic.proxy;
+
+import org.springframework.util.StopWatch;
+
+public class CashPerf implements Payment {
+	Payment cash = new Cash();
+
+	@Override
+	public void pay(int amount) {
+		StopWatch stopWatch = new StopWatch();
+		stopWatch.start();
+
+		cash.pay(amount);
+
+		stopWatch.stop();
+		System.out.println(stopWatch.prettyPrint());
+	}
+}
diff --git a/src/main/java/org/springframework/samples/petclinic/proxy/CreditCard.java b/src/main/java/org/springframework/samples/petclinic/proxy/CreditCard.java
deleted file mode 100644
index 1f2798ee8..000000000
--- a/src/main/java/org/springframework/samples/petclinic/proxy/CreditCard.java
+++ /dev/null
@@ -1,14 +0,0 @@
-package org.springframework.samples.petclinic.proxy;
-
-public class CreditCard implements Payment {
-	Payment cash = new Cash();
-
-	@Override
-	public void pay(int amount) {
-		if (amount > 100) {
-			System.out.println(amount + " 신용 카드");
-		} else {
-			cash.pay(amount);
-		}
-	}
-}
diff --git a/src/main/java/org/springframework/samples/petclinic/proxy/Store.java b/src/main/java/org/springframework/samples/petclinic/proxy/Store.java
index aa5600ac8..2600230ce 100644
--- a/src/main/java/org/springframework/samples/petclinic/proxy/Store.java
+++ b/src/main/java/org/springframework/samples/petclinic/proxy/Store.java
@@ -8,7 +8,7 @@ public class Store {
 		this.payment = payment;
 	}
 
-	public void buySomething() {
-		payment.pay(100);
+	public void buySomething(int amount) {
+		payment.pay(amount);
 	}
 }
diff --git a/src/test/java/org/springframework/samples/petclinic/proxy/StoreTest.java b/src/test/java/org/springframework/samples/petclinic/proxy/StoreTest.java
new file mode 100644
index 000000000..f2e3b6bb3
--- /dev/null
+++ b/src/test/java/org/springframework/samples/petclinic/proxy/StoreTest.java
@@ -0,0 +1,16 @@
+package org.springframework.samples.petclinic.proxy;
+
+import org.junit.Test;
+
+import static org.junit.Assert.*;
+
+public class StoreTest {
+
+	@Test
+	public void testPay() {
+		Payment cashPerf = new CashPerf();
+		Store store = new Store(cashPerf);
+		store.buySomething(100);
+	}
+
+}