On section 2

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

     public void setAccountNumber(String accountNumber) {
         this.accountNumber = accountNumber;
     }
+
+    @Override
+    public int compareTo(Payment other) {
+        return this.getShortDescription().compareTo(other.getShortDescription());
+    }
 }

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

     public void setId(Long id) {
         this.id = id;
     }
+
+    @Override
+    public int compareTo(Payment other) {
+        return this.getShortDescription().compareTo(other.getShortDescription());
+    }
 }

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

+package com.zipcoder.payment;
+
+public class PayPal implements Payment {
+
+    private Long id = 0L;
+    private String payerName;
+    private String email;
+
+    public PayPal(Long id, String name, String email) {
+        this.id = id;
+        this.payerName = name;
+        this.email = email;
+
+    }
+
+    @Override
+    public Long getId() {
+        return id;
+    }
+
+    @Override
+    public String getPayerName() {
+        return payerName;
+    }
+
+    @Override
+    public String getShortDescription() {
+        return "PayPal " + this.payerName + " " + getEmail();
+    }
+
+    public void setPayerName(String payerName) {
+        this.payerName = payerName;
+    }
+
+    public void setId(Long id) {
+        this.id = id;
+    }
+
+    public String getEmail() {
+        return email;
+    }
+
+    public void setEmail(String email) {
+        this.email = email;
+    }
+
+    @Override
+    public int compareTo(Payment other) {
+        return this.getShortDescription().compareTo(other.getShortDescription());
+    }
+}

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

 package com.zipcoder.payment;
 
-public interface Payment {
+public interface Payment extends Comparable<Payment>{
 
     Long getId();
 

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

+package com.zipcoder.payment;
+
+import org.junit.Assert;
+import org.junit.Test;
+
+public class PayPalTest {
+
+    //Given
+    PayPal customer = new PayPal(1L, "Lauren Green", "lauren@mail.com");
+    PayPal customer2 = new PayPal(2L, "Hayden Stewart", "hayden@mail.com");
+
+    @Test
+    public void testId() {
+        //When
+        Long expected = 3L;
+        customer.setId(3L);
+        Long actual = customer.getId();
+
+        //Then
+        Assert.assertEquals(expected, actual);
+
+    }
+
+    @Test
+    public void testName() {
+        //When
+        String expected = "Lauren Stewart";
+        customer.setPayerName("Lauren Stewart");
+        String actual = customer.getPayerName();
+
+        //Then
+        Assert.assertEquals(expected, actual);
+
+    }
+
+    @Test
+    public void testEmail() {
+        //When
+        String expected = "lgreen@mail.com";
+        customer.setEmail("lgreen@mail.com");
+        String actual = customer.getEmail();
+
+        //Then
+        Assert.assertEquals(expected, actual);
+
+    }
+
+
+    @Test
+    public void testShortDescription() {
+        //When
+        String expected = "PayPal Hayden Stewart hayden@mail.com";
+        String actual = customer2.getShortDescription();
+
+        //Then
+        Assert.assertEquals(expected, actual);
+
+    }
+
+}