When a new opportunity is created, all contacts on the corresponding account need to have the following info added to their description: Opp creator's name , Opp close date

AddOppInfoToContactsTrigger

/*
 When a new opportunity is created, all contacts on the corresponding account need to have
 the following info added to their description: Opp creator's name , Opp close date
  
*/

trigger AddOppInfoToContacts on Opportunity (after insert) {
	
    for(Opportunity opp : Trigger.new) {
        if(opp.AccountId != null) {
            //Get all contacts we need to update
            List<Contact> contacts = [SELECT Id, Description
                                        FROM Contact
                                       WHERE AccountId = :opp.AccountId];
            
            //Get opp creator info
            User oppCreator = [SELECT Name
                                 FROM User
                                WHERE Id = :opp.OwnerId];  
            
            String oppInfo = 'New opportunity created by ' +
                			 oppCreator.Name + ' with close date ' +
                			 String.valueOf(opp.CloseDate) + '.';
            
            if(!contacts.isEmpty()) {
                for(Contact con : contacts){
                    String newContactDesc = oppInfo;
                    
                    //Add the old description to the end if there already exists any description
                    if(con.Description != null){
                        newContactDesc += '\n\n' + con.Description;
                    }
                    
                    con.Description = newContactDesc;
                }
                
                update contacts;
            }
        }
    }
}


//Test Class

@isTest 
private class AddOppInfoToContactsTest {

    @isTest static void createOppOnAccount(){
        
        Account acc = new Account();
        acc.Name = 'Windsor Hotels';
        insert acc;
        
        List<Contact> contacts = new List<Contact>();
        for(Integer i = 0; i < 3; i++){
            String iString = String.valueOf(i);
            Contact myCon = new Contact();
            myCon.LastName = iString;
            myCon.AccountId = acc.Id;
            myCon.Description = iString;
            contacts.add(myCon);
        }
        insert contacts;
        
        Opportunity opp = new Opportunity();
        opp.Name = 'Windsor Hotels Atlanta Deal';
        opp.StageName = 'Prospecting';
        opp.CloseDate = Date.today();
        opp.AccountId = acc.Id;
        insert opp;
        
        List<Contact> updatedContacts = [SELECT Description
                                           FROM Contact
                                          WHERE AccountId = :acc.Id];
        
        opp = [SELECT CreatedBy.Name, CloseDate
                 FROM Opportunity
                WHERE Id = :opp.Id];
        
        for(Contact con : updatedContacts){
            System.assert(con.Description.contains(opp.CreatedBy.Name));
            System.assert(con.Description.contains(String.valueOf(opp.CloseDate)));
        }
    }
}