compare

src/main/java/com/zipcoder/payment/PaymentSortByPayer.java

@@ -1,4 +1,10 @@
 package com.zipcoder.payment;
 
-public class PaymentSortByPayer {
+import java.util.Comparator;
+
+public class PaymentSortByPayer implements Comparator<Payment> {
+
+    public int compare(Payment payment1, Payment payment2) {
+        return payment1.compareTo(payment2);
+    }
 }

src/test/java/com/zipcoder/payment/PaymentSortByPayerTest.java

@@ -0,0 +1,44 @@
+package com.zipcoder.payment;
+
+import org.junit.Assert;
+import org.junit.Before;
+import org.junit.Test;
+
+public class PaymentSortByPayerTest {
+    private PaymentSortByPayer test;
+
+    @Before
+    public void initialize() {
+        test =  new PaymentSortByPayer();
+    }
+
+    @Test
+    public void compareTest01() {
+        Check payment1 = new Check(100,"Aaron Aaronson", "1234567", "764321");
+        CreditCard payment2 = new CreditCard(200, "Zach Zachariah", "455555", 5, 2022);
+
+        int actual = test.compare(payment1, payment2);
+
+        Assert.assertTrue(actual > 0);
+    }
+
+    @Test
+    public void compareTest02() {
+        Check payment1 = new Check(300,"Zaron Aaronson", "1234567", "764321");
+        PayPal payment2 = new PayPal(15,"Momo Hashimoto", "kawaii54@line.com");
+
+        int actual = test.compare(payment1, payment2);
+
+        Assert.assertTrue(actual < 0);
+    }
+
+    @Test
+    public void compareTest03() {
+        Check payment1 = new Check(300,"Zaron Aaronson", "1234567", "764321");
+        Check payment2 = new Check(300,"Zaron Aaronson", "1234567", "764321");
+
+        int actual = test.compare(payment1, payment2);
+
+        Assert.assertTrue(actual == 0);
+    }
+}