How to update parent Case when updating EmailMessage

Question

Long time reader first question :)

I have a before insert trigger on EmailMessage, but I also need to update the Parent Case - which works fine. I believe I have to use before insert as I am updating the TextBody/HTMLBody of the EmailMessage and it cannot be updated once saved. However I have not been able to test the Parent Case update, the EmailMessage tests are fine.

Now I read in this situation it's best to use an after insert trigger for the Parent updates but I can't do this completely because of the EmailMessage limitation. So it is possible to cover the Parent Case update in the test methods (currently on 85%), or have I missed something in terms of my trigger/class structure?

Thanks in advance.

Further scenario info: We want to mask/replace certain details on an inbound email, then also mark the Parent Case so we can report on when this has happened and also make it obvious to the user on the Case record itself.

Class below (hope I've used the correct tag for readability). I've added comments for the lines I can't cover in my existing test. When querying the Case these updates are not showing (although they are applied in out of the test method).

public class MaskClass{   

    Public Static EmailMask (List<EmailMessage> newEm){

        Set<String> emPId = new Set<String>();
        String mask = System.Label.Mask;
        String regEx = System.Label.Pattern;
        String MaskedText;
        Boolean EmailIncoming;


        for(EmailMessage emx:newEm){
            If(emx.TextBody !=null){

            pattern p = Pattern.compile(regEx);
            matcher m = p.matcher(emx.TextBody);             

            //If pattern matched replace match with mask
            if(m.find()){
                system.debug('**EmailMask**: Card Details Detected in Email');
                emx.TextBody = m.replaceAll(mask);
        emx.HtmlBody = m.replaceAll(mask);             
                System.debug('**EmailMask ParentId: '+emx.ParentId);
                MaskedText = emx.TextBody;
                EmIncoming = emx.Incoming;
                emPId.add(emx.ParentId);

            }
            else{
                system.debug('**EmailMask**: No Detection');
            }
        System.debug('**EmailMask** Masked Text: '+MaskedText);    
        }
            else{
                system.debug('**EmailMask TextBody is Null** '+emx.Subject);
            }           
        }
        //Flag Parent Case Record
        If(emPid != null && EmIncoming == True){
    List<Case> cx = [SELECT Id, CaseNumber FROM Case WHERE Id IN :emPId];    //Not covered   
        for(Case cxUpdate:cx){ //Not covered
            cxUpdate.Flag__c=True; //Not covered
            system.debug('**EmailMask Debug** CaseNumber: '+cxUpdate.CaseNumber);
            update cxUpdate; //Not covered
          }            
        }
    }
    public static void ParentCaseMask (List<Case> newCase){
        String mask = System.Label.Mask;
        String regEx = System.Label.Pattern;

        for(Case cxUpdate:newCase){
            If(cxUpdate.Description != null){
                pattern pc = pattern.compile(regEx);
                matcher mc = pc.matcher(cxUpdate.Description);
                If(mc.find()){
                    system.debug('**CaseMask**: Detected in Case Description');                            
                    cxUpdate.Description = mc.replaceAll(mask);
                    cxUpdate.Flag__c=True;
                    system.debug('**CaseMask: '+cxUpdate.Flag__c);
                }
                Else{
                    system.debug('**CaseMask*: No match in Case Description');
                }                
            }
            Else{
                    system.debug('**CaseMask**: Case Description is Null');
                }            
          }
    }
}

Answer 1

If an EmailMessage is inserted, any before insert and after insert trigger on EmailMessage will execute. The after insert trigger can do a SOQL query on the parent Case and then update that Case.

//  after insert trigger snippet; assume variable theMask contains a unique mask string
Set<ID> csIdUpdSet = new Set<ID>();
for (EmailMessage em : Trigger.new) 
  if (em.htmlbody.contains(theMask) || em.textBody.contains(theMask))
     csIdUpdSet.add(em.parentId);

List<Case> csUpdList = [select id, has_mask_event__c from Case where id IN :csIdUpdSet]
for (Case cs : csUpdList)
   cs.has_mask_event__c = true;
update csUpdList;

// end snippet