added lambda

pom.xml

          xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
          xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 http://maven.apache.org/xsd/maven-4.0.0.xsd">
     <modelVersion>4.0.0</modelVersion>
-
+    <build>
+        <plugins>
+            <plugin>
+                <groupId>org.apache.maven.plugins</groupId>
+                <artifactId>maven-compiler-plugin</artifactId>
+                <configuration>
+                    <source>1.8</source>
+                    <target>1.8</target>
+                </configuration>
+            </plugin>
+        </plugins>
+    </build>
     <groupId>com.zipcoder</groupId>
     <artifactId>payment</artifactId>
     <version>1.0-SNAPSHOT</version>

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

 package com.zipcoder.payment;
 
 import java.util.Arrays;
+import java.util.Comparator;
 
 public class PaymentPresenter {
     Payment[] payments;
 
     public String toStringById(Payment[] payments){
         StringBuilder output = new StringBuilder();
-        Arrays.sort(payments,new PaymentSortById());
+        Arrays.sort(payments,(p, q) -> p.getId().compareTo(q.getId()));
 
         for (int i=0; i<payments.length; i++) {
             output.append(payments[i].getShortDescription()+"\n");

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

     public int compare(Payment o1, Payment o2) {
         return o1.getPayerName().compareTo(o2.getPayerName());
     }
+
 }

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

     public void compareToTest(){
 
         int expected= 1;
-        int actual= test.getShortDescription().compareTo(test1.getShortDescription());
+        int actual= test.compareTo(test1);
         Assert.assertTrue(actual<expected);
     }
 }

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

 package com.zipcoder.payment;
 
 import org.junit.Assert;
-import org.junit.Before;
 import org.junit.Test;
 
 public class CreditCardTest {
 
     @Test
     public void getIdTest(){
-
+        test.setId(1L);
         Long expected= 1L;
         Long actual= test.getId();
         Assert.assertEquals(expected,actual);
     @Test
     public void compareToTest(){
 
-        int expected= 1;
-        int actual= test.getShortDescription().compareTo(test1.getShortDescription());
-        Assert.assertEquals(expected,actual);
+        int actual= test.compareTo(test1);
+        Assert.assertTrue(actual>0);
     }
 }

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

 import org.junit.Assert;
 import org.junit.Test;
 
+import java.util.Comparator;
+
 public class PaymentPresenterTest {
 
     @Test
     Payment paypal = new Paypal(81L, "Tamara Mowry", "tamara@mowry.com");
     Payment check = new Check(120L, "Tia Mowry", "11432543", "134344551");
 
+
     payments[0]=paypal;
     payments[1]=check;
 

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

 package com.zipcoder.payment;
 
 import org.junit.Assert;
+import org.junit.Before;
 import org.junit.Test;
 
 public class PaymentSortByPayerTest {
 
-    CreditCard test2 = new CreditCard(1L,"chad","123456789",1,2020);
-    Check test1 = new Check(2L,"brad","98 76 5432","0987654321");
-    PaymentSortByPayer test = new PaymentSortByPayer();
+    CreditCard test2;
+    Check test1;
+    PaymentSortByPayer test;
+
+    @Before
+    public void setUp(){
+        test2 = new CreditCard(1L,"chad","123456789",1,2020);
+        test1 = new Check(2L,"brad","98 76 5432","0987654321");
+        test = new PaymentSortByPayer();
+    }
+
+
     @Test
     public void compareTest(){
+        //Given
 
-        int expected= 1;
+        //When
         int actual= test.compare(test1,test2);
-        Assert.assertTrue(actual<expected);
+        //Assert
+        Assert.assertTrue(actual<0);
     }
 }

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

 package com.zipcoder.payment;
 
 import org.junit.Assert;
+import org.junit.Before;
 import org.junit.Test;
 
+
 public class PaypalTest {
-    Paypal test = new Paypal(1L,"Chad Hallinan","hallinanc@susqu.edu");
-    Paypal test1 = new Paypal(2L,"brad","bradbrobrill");
+    Paypal test;
+    Paypal test1;
+
+    @Before
+    public void before(){
+        test = new Paypal(1L,"Chad Hallinan","hallinanc@susqu.edu");
+        test1 = new Paypal(2L,"brad","bradbrobrill");
+    }
+
+    @Test
+    public void liveTest(){
+        test.setPayerName("Nafis");
+        String actual= test.getPayerName();
+        String expected = "Nafis";
+        Assert.assertEquals(actual, expected);
+    }
+
     @Test
     public void getIdTest(){
 
     @Test
     public void compareToTest(){
 
-        int expected= 1;
-        int actual= test.getShortDescription().compareTo(test1.getShortDescription());
-        Assert.assertTrue(actual<expected);
+        int actual= test.compareTo(test1);
+        Assert.assertTrue(actual<0);
     }
 }