Salesforce Test Class - System NullPointerException Attempt to de-reference a null object

Question

Salesforce Test Class - Facing - System.NullPointerException: Attempt to de-reference a null object Error while trying to Run Test Class

APEX class

public class NewAccountCreation {
public Account account{get;set;}
public void save(){
Account acc = new Account();
// User enter values in vf page and we are capturing and creating account
acc.name = account.Name;
//acc.address = account.adress;
Insert acc;
}
}
Test Class

@isTest
public class TestNewAccountCreation {
    @isTest static void TestNewAccountCreationMethod(){
        NewAccountCreation testAccount = new NewAccountCreation ();
        Account acc = new Account(Name='TestAcct');
        Insert acc;
        system.debug(''+acc);
        testAccount.save();
        System.assert([Select Id From Account].size()==1);
    }
}
 

Error: System.NullPointerException: Attempt to de-reference a null object

StackTrace: Class.NewAccountCreation.save: line 6, column 1 Class.TestNewAccountCreation.TestNewAccountCreationMethod: line 9, column 1