Solving Use Future Methods Challenge
The Trailhead challenge says:   Create an Apex class that uses the @future annotation to update Account records. 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...