trigger Addtogroup1 on Contact (after insert, after update) {

  List<GroupMember> GMlist = new List<GroupMember>();
   Set<String> contactEmails = new Set<String>();
   for(Contact con : Trigger.New) {
      //create a set with the contact email addresses
      contactEmails.add(con.email);
   }

   //query for the related users and put them in a map,
   //where the key is the email and the value is the user
   Map<String, User> emailUserMap = new Map<String, User> ();
   for(User aUser : [select id, email from User where email in : contactEmails]){
      emailUserMap.put(aUser.email, aUser);
   }
       system.debug(emailUserMap);
       List<Id> userIdList = new List<Id>();
  for(Contact con : Trigger.New) {
    if(con.Public_Group_Service_Partner_Content1__c == TRUE) {

         userIdList.add(emailUserMap.get(con.email).id);

      }
  }

  //dymanically get the get group id.
  Group theGroup = [select id from Group where Name = 'Service Partner Content'];
  if(null != theGroup){
      //call the contact trigger helper if the group exists.
      //This method adds the user to the group
      ContactTriggerHelper.addUsersToGroup(theGroup.id,userIdList );
  }

public class ContactTriggerHelper{

  //future call to do the group adding.  the future call will spawn a new thread.
  @future
  public static void addUsersToGroup(String groupId, List<Id> userIds){
      List<GroupMember> GMlist = new List<GroupMember>();
      for(ID userId: userIds){
          GroupMember gm = new GroupMember();
          gm.GroupId = groupId;
          gm.UserOrGroupId = userId;
          gmList.add(GM);
      }


      if(gmList.size() > 0){
          insert gmList;
      }
  }

@isTest

// Insert contact with your required field.

    Contact cnt = new Contact();
    cnt.LastName = 'Test contact';
    cnt.Email = 'test@test.com';
    cnt.Public_Group_Technology_Partner_Content__c = true;
    insert cnt;

    // Insert user

    Profile p = [SELECT Id FROM Profile WHERE Name='System Administrator'];
    User u = new User(Alias = 'standt', Email='test@test.com',
    EmailEncodingKey='UTF-8', LastName='Testing', LanguageLocaleKey='en_US',
    LocaleSidKey='en_US', ProfileId = p.Id,
    TimeZoneSidKey='America/Los_Angeles', UserName='standarduser@testorg.com');
    insert u;

    // Insert Group
    if(isGroup == true)
    {
        Group grp = new Group();
        grp.Name = 'Technology Partner Content';
        grp.DeveloperName = 'Technology Partner Content';
        insert grp;
    }
}



static testMethod void insertWithGroup()
{
    createGroup(true);
}

static testMethod void insertWithoutGroup()
{
    createGroup(false);
}