I have been writing a test class to get coverage on the trigger but I am having trouble getting past the 11%.  Again I am a beginner so I could use a little direction.  I'm still a little fuzzy on test coverage.  To get a good test scenario I am going to do the following.  Create 1 opportunity, 1 deposit, one account, link them and insert them to fire my trigger then do a system.assertEquals to test the result.  Then I want to do it with 15 Opportunities.  This is what I have so far.

My trigger is

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trigger DepositRollup on Opportunity (after insert, after update,after delete) {

//instantiate opportunity

Opportunity thisScreening = Trigger.New[0];

// retrieve from the DB all of the opportunities related to the current related deposit
if (thisScreening.Deposited__c != null){
   
    List<Opportunity> screenings = [SELECT Deposited__r.Name, Total_Collected__c, Total_cash__c, Total_checks__c, Total_charges__c
    FROM Opportunity WHERE Deposited__c =: thisScreening.Deposited__c];
   
    //instantiate this related deposit

    Deposit__c thisDeposit = screenings[0].Deposited__r;


    double totalSumCash = 0, totalSumChecks = 0, totalSumCharges = 0, totalSumSales = 0;

    //iterate through each opportunity in this list, calculate the sum on the deposit

    for(Opportunity o :screenings){
      totalSumCash += o.Total_Cash__c;
      totalSumCharges += o.Total_Charges__c;
      totalSumChecks += o.Total_Checks__c;
      totalSumSales += o.Total_Collected__c;
    }
     thisDeposit.Sum_of_Cash__c = totalSumCash;
     thisDeposit.Sum_of_Checks__c = totalSumChecks;
     thisDeposit.Sum_of_Credit__c = totalSumCharges;
     thisDeposit.Sum_of_Sales__c = totalSumSales;

// update the related deposit record in the DB
  
   update thisDeposit;
    }
}

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@istest
private class DepositTestClass {
   
    //create account
    static testMethod void TestDepositRUTrigger(){
    Account acct = new Account(name='Test Account');
        insert acct;
   
    //create deposit with name and todays date   
        Deposit__c dep = new Deposit__c();
        dep.Name_of_Deposit__c = 'Deposit 2';
        dep.Deposit_Date__c = System.Today();
        insert dep;
   
    //insert a single opportunity
    Opportunity[] createopps = new Opportunity[]{};
   
    double SumCashResult =0;
   
    Opportunity sop = new Opportunity(AccountId=acct.Id,Deposited__c=dep.Name,
    Name='screening',CloseDate=System.today(),Scout__Sales_Order_Number__c ='1199556',
    Total_cash__c=10, Total_checks__c=20, Total_Charges__c=30, StageName='Event Occurred', RecordTypeID='012700000001THf');
    createopps.add(sop);
   
    //insert opportunity to fire the trigger
   
    insert createopps;
   
    //Run query to grab a field from the deposit affected by the trigger linked to the opportunity and check

   
    for(Opportunity ch:    [SELECT Deposited__r.Name,Deposited__r.Sum_of_Cash__c FROM Opportunity where Deposited__r.Name ='deposit 2']){
    SumCashResult = ch.Deposited__r.Sum_of_cash__c;
    }
    System.assertEquals(10, SumCashResult);
   
    }

 

}

I am going to use a for loop for the 15 opportunities but want to do it with one first. Once I run the tests it tells me I need coverage on the screenings list but I don't understand why my system.assertEquals isn't covering it.  I still need coverage on the rest but can anyone help me from here?

Thanks