hi everyone, i had an after trigger to help on copy specific attachment from proposal to its parent opportunity, the trigger code is like this

trigger CopyAttachmentsToOpps on Attachment (after insert) {

    // collect a set of Proposal 'parent' IDs from the attachments inserted
    Set<Id> proposalIds = new Set<Id>();
    for(Attachment file : Trigger.new) {
// only collect those that are for the proposal object (others can be ignored)
    
        if(file.ParentId.getSObjectType() == Apttus_Proposal__Proposal__c.getSObjectType() && file.Name.containsIgnoreCase('quote English 20')) {
            proposalIds.add(file.ParentId);
        }
    }

    if(!proposalIds.isEmpty()) {

        // find the Opportunity to which the Proposal relates
        Map<Id,Apttus_Proposal__Proposal__c> proposalMap = new Map<Id,Apttus_Proposal__Proposal__c>([Select Apttus_Proposal__Opportunity__c From Apttus_Proposal__Proposal__c Where Id IN :proposalIds ]);        

        List<Attachment> attachments = new List<Attachment>();

        for(Attachment file : Trigger.new) 
        {
            Attachment newFile = file.clone();
            newFile.ParentId = proposalMap.get(file.ParentId).Apttus_Proposal__Opportunity__c;
            attachments.add(newFile);
        }
        // insert the cloned attachments
        insert attachments;
    }


}

i want to write an test class to deploy it into produciton, here is so far i did ,it only coverage 30% how can i improve that?

@isTest 
public class TestCopyAttachmentsToOpps {
    static testMethod void testCopyattachs() {

       // create quote attachment from scratch

       Attachment att   = new attachment();
       att.body  =  Blob.valueOf('Unit Test Attachment Body 1');
       att.name = 'quote english hahahah';
       att.ParentId= 'a5no0000000GxEz';
       insert att;
       
 Map<Id,Apttus_Proposal__Proposal__c> proposalMap = new Map<Id,Apttus_Proposal__Proposal__c>([Select Apttus_Proposal__Opportunity__c From Apttus_Proposal__Proposal__c Where Id ='a5no0000000GxEz' ]);        

        List<Attachment> attachments = new List<Attachment>();
            attachment newfile= new attachment();
            newFile.ParentId = '006o000000NEmIB';
            newfile.body=att.body;
            newfile.name=att.name;
        insert attachments;
    }


}