getting NullPointerException when try to persist entity - jpa

Question

I have the following code. When I run the junit test it's creating a table and fields but they are null. I'm also getting a NullPointerException..
Why isn't my user being added?
java.lang.NullPointerException
at com.testproject.repo.JPAUserRepo.addUser(JPAUserRepo.java:15)
at com.testproject.manager.UserManager.saveUser(UserManager.java:18)
at com.testproject.manager.test.UserManagerTest.testSaveUser(UserManagerTest.java:44)
at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:57)
at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
at java.lang.reflect.Method.invoke(Method.java:606)
at org.junit.runners.model.FrameworkMethod$1.runReflectiveCall(FrameworkMethod.java:47)
at org.junit.internal.runners.model.ReflectiveCallable.run(ReflectiveCallable.java:12)
at org.junit.runners.model.FrameworkMethod.invokeExplosively(FrameworkMethod.java:44)
at org.junit.internal.runners.statements.InvokeMethod.evaluate(InvokeMethod.java:17)
at org.junit.internal.runners.statements.RunBefores.evaluate(RunBefores.java:26)
at org.junit.internal.runners.statements.RunAfters.evaluate(RunAfters.java:27)
at org.junit.runners.ParentRunner.runLeaf(ParentRunner.java:271)
at org.junit.runners.BlockJUnit4ClassRunner.runChild(BlockJUnit4ClassRunner.java:70)
at org.junit.runners.BlockJUnit4ClassRunner.runChild(BlockJUnit4ClassRunner.java:50)
at org.junit.runners.ParentRunner$3.run(ParentRunner.java:238)
at org.junit.runners.ParentRunner$1.schedule(ParentRunner.java:63)
at org.junit.runners.ParentRunner.runChildren(ParentRunner.java:236)
at org.junit.runners.ParentRunner.access$000(ParentRunner.java:53)
at org.junit.runners.ParentRunner$2.evaluate(ParentRunner.java:229)
at org.junit.runners.ParentRunner.run(ParentRunner.java:309)
at org.eclipse.jdt.internal.junit4.runner.JUnit4TestReference.run(JUnit4TestReference.java:50)
at org.eclipse.jdt.internal.junit.runner.TestExecution.run(TestExecution.java:38)
at org.eclipse.jdt.internal.junit.runner.RemoteTestRunner.runTests(RemoteTestRunner.java:467)
at org.eclipse.jdt.internal.junit.runner.RemoteTestRunner.runTests(RemoteTestRunner.java:683)
at org.eclipse.jdt.internal.junit.runner.RemoteTestRunner.run(RemoteTestRunner.java:390)
at org.eclipse.jdt.internal.junit.runner.RemoteTestRunner.main(RemoteTestRunner.java:197)
User.java
#Entity
#Table(name="USER")
#NamedQuery(name="getAllUser", query="SELECT a FROM User a ORDER BY a.userid")
public class User implements Serializable {
private static final long serialVersionUID = 1L;
#Id
#GeneratedValue(strategy=GenerationType.AUTO)
#Column(name="USER_ID")
private long userid;
#Column(name="USERNAME")
private String username;
#Column(name="PASSWORD")
private String password;
#Column(name="USER_EMAIL")
private String userEmail;
#Column(name="USER_PHONE")
private int userPhone;
public User() {
// TODO Auto-generated constructor stub
}
public User(String username, String password, String email, int userPhone) {
super();
this.username = username;
this.password = password;
this.userEmail = email;
this.userPhone = userPhone;
}
//Getters and Setters
JPAUserRepo.java
public class JPAUserRepo implements UserRepo {
EntityManager em;
#Override
public void addUser(User user) {
em.persist(user);
}
UserManager.java
public class UserManager {
UserRepo userRepo;
public void saveUser(User user){
userRepo.addUser(user);
}
UserManagerTest.java
public class UserManagerTest {
EntityManager em;
UserManager userManager;
User user;
#Before
public void setUp() throws Exception {
EntityManagerFactory factory = Persistence.createEntityManagerFactory("persistenceUnitMySQL");
em = factory.createEntityManager();
userManager = new UserManager();
JPAUserRepo jpaUserRepo = new JPAUserRepo();
userManager.setUserRepo(jpaUserRepo);
em.getTransaction().begin();
user = new User("name", "password", "mail#mail.com", 1561234567);
}
#After
public void tearDown() throws Exception {
em.getTransaction().commit();
}
#Test
public void testSaveUser() {
userManager.saveUser(user);
}
}