I'm trying to write a test class so I can get over the 75% coverage (no coverage was written/included for this class). I'm getting the null object error on line 9 - System.assertEquals('testuserlong@salesforce.com', u.userName); 

Any help would be appreciated! Thanks in advance.

Here's the Class:
global class AutocreatedRegHandler1516897783772 implements Auth.RegistrationHandler{
global boolean canCreateUser(Auth.UserData data) {
    //TODO: Check whether we want to allow creation of a user with this data
    //Set<String> s = new Set<String>{'usernamea', 'usernameb', 'usernamec'};
    //if(s.contains(data.username)) {
        //return true;
    //}
    return false;
}

global User createUser(Id portalId, Auth.UserData data){
    if(!canCreateUser(data)) {
        //Returning null or throwing an exception fails the SSO flow
        return null;
    }
    //The user is authorized, so create their Salesforce user
    User u = new User();
    Profile p = [SELECT Id FROM profile WHERE name='Standard User'];
    //TODO: Customize the username. Also check that the username doesn't already exist and
    //possibly ensure there are enough org licenses to create a user. Must be 80 characters
    //or less.
    u.username = data.username + '@myorg.com';
    u.email = data.email;
    u.lastName = data.lastName;
    u.firstName = data.firstName;
    String alias = data.username;
    //Alias must be 8 characters or less
    if(alias.length() > 8) {
        alias = alias.substring(0, 8);
    }
    u.alias = alias;
    u.languagelocalekey = UserInfo.getLocale();
    u.localesidkey = UserInfo.getLocale();
    u.emailEncodingKey = 'UTF-8';
    u.timeZoneSidKey = 'America/Los_Angeles';
    u.profileId = p.Id;
    return u;
}

global void updateUser(Id userId, Id portalId, Auth.UserData data){
    User u = new User(id=userId);
    //TODO: Customize the username. Must be 80 characters or less.
    //u.username = data.username + '@myorg.com';
    u.email = data.email;
    u.lastName = data.lastName;
    u.firstName = data.firstName;
    //String alias = data.username;
    //Alias must be 8 characters or less
    //if(alias.length() > 8) {
        //alias = alias.substring(0, 8);
    //}
    //u.alias = alias;
    update(u);
}
}

Here's the Test Class:
@isTest
private class AutocreatedRegHandler1516897783772Test {
static testMethod void testCreateAndUpdateUser() {
    AutocreatedRegHandler1516897783772 handler = new AutocreatedRegHandler1516897783772();
    Auth.UserData sampleData = new Auth.UserData('testId', 'testFirst', 'testLast',
        'testFirst testLast', 'testuser@example.org', null, 'testuserlong', 'en_US', 'facebook',
        null, new Map<String, String>{'language' => 'en_US'});
    User u = handler.createUser(null, sampleData);
    System.assertEquals('testuserlong@salesforce.com', u.userName);
    System.assertEquals('testuser@example.org', u.email);
    System.assertEquals('testLast', u.lastName);
    System.assertEquals('testFirst', u.firstName);
    System.assertEquals('testuser', u.alias);
    insert(u);
    String uid = u.id;
     
    sampleData = new Auth.UserData('testNewId', 'testNewFirst', 'testNewLast',
        'testNewFirst testNewLast', 'testnewuser@example.org', null, 'testnewuserlong', 'en_US', 'facebook',
        null, new Map<String, String>{});
    handler.updateUser(uid, null, sampleData);
     
    User updatedUser = [SELECT userName, email, firstName, lastName, alias FROM user WHERE id=:uid];
    System.assertEquals('testnewuserlong@salesforce.com', updatedUser.userName);
    System.assertEquals('testnewuser@example.org', updatedUser.email);
    System.assertEquals('testNewLast', updatedUser.lastName);
    System.assertEquals('testNewFirst', updatedUser.firstName);
    System.assertEquals('testnewu', updatedUser.alias);
}
}

Here's my Trigger:
trigger SoldCustomer on Opportunity (after update) {
    for (Opportunity opp : Trigger.new) {
        if (opp.Account.Type != 'Customer' && opp.StageName == 'Sold' && opp.Account.Type != null) {
            opp.Account.Type = 'Customer';
        }
    }
}

Here's my Test Class:
@isTest
private class SoldCustomerTest {

    @isTest static void CreateOpp() {
        // Create Account
        Account acc = new Account();

        acc.Name = 'Created Account';
        acc.Type = 'Prospect';
        String accId = acc.Id;

        Opportunity opp = new Opportunity();
        opp.StageName = 'Discovery';
        opp.CloseDate = date.parse('12/27/2019');
        opp.Name = 'Sold Customer Test Opp';
        opp.AccountId = accId;
    }

    @isTest static void UpdateOpp() {
        List<Opportunity> records = [
        SELECT Id FROM Opportunity WHERE Name = 'Sold Customer Test Opp'
        ];

        for (Opportunity record : records) {
            record.StageName = 'Sold';
        }

        update records;
    }
}
When I run the test class, it shows no coverage for the trigger. This is my 2nd trigger and I'm really excited about asking my first question. Hopefully, someone can help. Thanks in advance!

I'm trying to write a test class so I can get over the 75% coverage (no coverage was written/included for this class). I'm getting the null object error on line 9 - System.assertEquals('testuserlong@salesforce.com', u.userName); 

Any help would be appreciated! Thanks in advance.

Here's the Class:
global class AutocreatedRegHandler1516897783772 implements Auth.RegistrationHandler{
global boolean canCreateUser(Auth.UserData data) {
    //TODO: Check whether we want to allow creation of a user with this data
    //Set<String> s = new Set<String>{'usernamea', 'usernameb', 'usernamec'};
    //if(s.contains(data.username)) {
        //return true;
    //}
    return false;
}

global User createUser(Id portalId, Auth.UserData data){
    if(!canCreateUser(data)) {
        //Returning null or throwing an exception fails the SSO flow
        return null;
    }
    //The user is authorized, so create their Salesforce user
    User u = new User();
    Profile p = [SELECT Id FROM profile WHERE name='Standard User'];
    //TODO: Customize the username. Also check that the username doesn't already exist and
    //possibly ensure there are enough org licenses to create a user. Must be 80 characters
    //or less.
    u.username = data.username + '@myorg.com';
    u.email = data.email;
    u.lastName = data.lastName;
    u.firstName = data.firstName;
    String alias = data.username;
    //Alias must be 8 characters or less
    if(alias.length() > 8) {
        alias = alias.substring(0, 8);
    }
    u.alias = alias;
    u.languagelocalekey = UserInfo.getLocale();
    u.localesidkey = UserInfo.getLocale();
    u.emailEncodingKey = 'UTF-8';
    u.timeZoneSidKey = 'America/Los_Angeles';
    u.profileId = p.Id;
    return u;
}

global void updateUser(Id userId, Id portalId, Auth.UserData data){
    User u = new User(id=userId);
    //TODO: Customize the username. Must be 80 characters or less.
    //u.username = data.username + '@myorg.com';
    u.email = data.email;
    u.lastName = data.lastName;
    u.firstName = data.firstName;
    //String alias = data.username;
    //Alias must be 8 characters or less
    //if(alias.length() > 8) {
        //alias = alias.substring(0, 8);
    //}
    //u.alias = alias;
    update(u);
}
}

Here's the Test Class:
@isTest
private class AutocreatedRegHandler1516897783772Test {
static testMethod void testCreateAndUpdateUser() {
    AutocreatedRegHandler1516897783772 handler = new AutocreatedRegHandler1516897783772();
    Auth.UserData sampleData = new Auth.UserData('testId', 'testFirst', 'testLast',
        'testFirst testLast', 'testuser@example.org', null, 'testuserlong', 'en_US', 'facebook',
        null, new Map<String, String>{'language' => 'en_US'});
    User u = handler.createUser(null, sampleData);
    System.assertEquals('testuserlong@salesforce.com', u.userName);
    System.assertEquals('testuser@example.org', u.email);
    System.assertEquals('testLast', u.lastName);
    System.assertEquals('testFirst', u.firstName);
    System.assertEquals('testuser', u.alias);
    insert(u);
    String uid = u.id;
     
    sampleData = new Auth.UserData('testNewId', 'testNewFirst', 'testNewLast',
        'testNewFirst testNewLast', 'testnewuser@example.org', null, 'testnewuserlong', 'en_US', 'facebook',
        null, new Map<String, String>{});
    handler.updateUser(uid, null, sampleData);
     
    User updatedUser = [SELECT userName, email, firstName, lastName, alias FROM user WHERE id=:uid];
    System.assertEquals('testnewuserlong@salesforce.com', updatedUser.userName);
    System.assertEquals('testnewuser@example.org', updatedUser.email);
    System.assertEquals('testNewLast', updatedUser.lastName);
    System.assertEquals('testNewFirst', updatedUser.firstName);
    System.assertEquals('testnewu', updatedUser.alias);
}
}