Hello everyone I could use some help on the using future Methods trailhead. Please keep in mind I am not an Apex coder at all but I am trying to learn as much as I can.

Here is the Task

Create an Apex class with a method using the @future annotation that accepts a List of Account IDs and updates a custom field on the Account object with the number of contacts associated to the Account. Write unit tests that achieve 100% code coverage for the class.
Create a field on the Account object called 'Number_of_Contacts__c' of type Number. This field will hold the total number of Contacts for the Account.
Create an Apex class called 'AccountProcessor' that contains a 'countContacts' method that accepts a List of Account IDs. This method must use the @future annotation.
For each Account ID passed to the method, count the number of Contact records associated to it and update the 'Number_of_Contacts__c' field with this value.
Create an Apex test class called 'AccountProcessorTest'.
The unit tests must cover all lines of code included in the AccountProcessor class, resulting in 100% code coverage.
Run your test class at least once (via 'Run All' tests the Developer Console) before attempting to verify this challenge.

I have written an Apex class and a Test class but I think I am doing them both Wrong: because when I try to check the challenge i Get this error

Challenge Not yet complete... here's what's wrong: 
The 'AccountProcessorTest' test class doesn't appear to be calling the 'AccountProcessor.countContacts' method between Test.startTest() and Test.stopTest().

When I run the Test class I get this error :

System.QueryException: List has no rows for assignment to SObject

Here is the CLASS:
 

public class AccountProcessor {
     @future

  public static void someFutureMethod(List<id> scope) {

   Account[] updates = new Account[] {};
        for (AggregateResult ar : [
                select AccountId a, count(Id) c
                from Contact
                where AccountId in :scope
                group by AccountId
                ]) {
            updates.add(new Account(
                    Id = (Id) ar.get('a'),
                    Number_of_Contacts__c = (Decimal) ar.get('c')
                    ));
        }
        update updates;
    }

}

Here is the Test Class:
 

@IsTest
public class AccountProcessorTest {
  public static testmethod void TestAccountProcessorTest() {
 
Test.startTest();
     Account a = new Account();
        a.Name = 'Test Account';
        Insert a;
      
      Contact cont = New Contact();
      
      cont.FirstName ='Bob';
      cont.LastName ='Masters';
      cont.AccountId = a.Id;
      Insert cont;

    Test.stopTest() ;
     Contact ACC = [select AccountId from Contact where id = :a.id LIMIT 1];

 
        System.assert(Cont.AccountId != null);
        System.assertequals(cont.id, ACC.AccountId);

  }}

I have used alot or diffrent google searches to get me this far. But I have not Idea if Im even remotly close to the right answer or not.


 

I have this very simple class..  

trigger RestrictContactByName on Contact (before insert, before update) {
    //check contacts prior to insert or update for invalid data
    For (Contact c : Trigger.New) {
        if(c.LastName == 'INVALIDNAME') {   //invalidname is invalid
            c.AddError('The Last Name "'+c.LastName+'" is not allowed for DML');
        }
    }
}

.. and the corresponding Test Class:  

@isTest
private class TestRestrictContactByName {

	@isTest static void metodoTest() {
		
		List listaContatti = new List();
		Contact c1 = new Contact(FirstName='Francesco', LastName='Riggio');
		Contact c2 = new Contact(LastName = 'INVALIDNAME');
		listaContatti.add(c1);
		listaContatti.add(c2);
		
		//insert listaContatti;
		
		// Perform test
        Test.startTest();
        Database.SaveResult [] result = Database.insert(listaContatti, false);
        Test.stopTest(); 
		
		c1.LastName = 'INVALIDNAME';
		update c1;
       		
	}
	
}

When I run the Test class from the Developer Console I get 100% of coverage on the RestrictContactByName class but, when I check the challenge on the trailhead it returns the error:

Challenge not yet complete... here's what's wrong: The 'RestrictContactByName' class did not achieve 100% code coverage via your test methods

Has someone had my same issue?

hello,

i am a newbie to salesforce and trying to complete this trailhead challenge and unable to find a way through apex to generate this method for creating new contacts with unique id. as one requirement to pass the challenge is "The 'generateRandomContacts' method must be capable of consistently generating contacts with unique first names."

If somebody successfully completed the task kindly help me.

regards,