Hi please help me write a test class for a schedulable apex class that sends an email to all users who have a checkbox on their user checked.
 

//Send email to users where receive Grants email = TRUE
public class NoActivityThisQrtr implements Schedulable {
    public void execute(SchedulableContext sc) {
        // Get list of opportunities where the opps> account last activity date not in the current quarter
        List<Opportunity> listOfnoactivityOps = [Select Id, Name, StageName ,Account_Name__c,Accouint_Last_Activity_Date__c
                                             From Opportunity 
                                             Where Accouint_Last_Activity_Date__c != THIS_FISCAL_QUARTER];
        
        // Get user ids in a list
        User adminProfile = [Select Id From User Where Receive_TB_Grant_Emails_Notifications__c = TRUE];
        List<Id> listOfUserIds = new List<Id>();
        for(User usr : [Select Id From User Where ProfileId = :adminProfile.Id]) {
            listOfUserIds.add(usr.Id);
        }
        
        // Get all the opportunities Name, StageName, Acccount and Account Last Activity Date in a String
        String closedOpportunities = 'Opportunity Name' + ' : ' + 'Stage' + ':' +'Account' + ':' +'Account Last Activity Date';
        for(Opportunity op : listOfnoactivityOps) {
            closedOpportunities = ClosedOpportunities + '\n' + op.Name + ' : ' + op.StageName + ':' + op.Account_Name__c +':' + OP.Accouint_Last_Activity_Date__c;
        }
        
        sendmail(listOfUserIds, closedOpportunities);
    }
    
    public void sendmail(List<Id> listOfUserIds, String closedOpportunities) {
        // Creating instance of email and set values
        Messaging.SingleEmailMessage email = new Messaging.SingleEmailMessage();
        email.setToAddresses(listOfUserIds);
        email.setSubject('Accounts without Activity this month');
        email.setPlainTextBody( 'Hello, Here are opportunities whose accounts havent had activity this quarter'+ 
            closedOpportunities);
        
        // Send email
        Messaging.sendEmail(new List<Messaging.SingleEmailMessage> {email});
    }
}

this is the test class i have, no errors but also no coverage
 

@isTest
private class NoActivityThisQrtrTest
{
    static testmethod void schedulerTest() 
    {
        String CRON_EXP = '0 0 0 15 3 ? *';
        
        // Create your test data
        List<Opportunity> listOfnoactivityOps = [Select Id, Name, StageName ,Account_Name__c,Accouint_Last_Activity_Date__c
                                             From Opportunity 
                                             Where Accouint_Last_Activity_Date__c != THIS_FISCAL_QUARTER];
        
        User adminProfile = [Select Id From User Where Receive_TB_Grant_Emails_Notifications__c = TRUE];
        List<Id> listOfUserIds = new List<Id>();
        for(User usr : [Select Id From User Where ProfileId = :adminProfile.Id]) {
            listOfUserIds.add(usr.Id);
        }
        
        Test.startTest();

            String jobId = System.schedule('ScheduleApexClassTest',  CRON_EXP, new NoActivityThisQrtr());
            CronTrigger ct = [SELECT Id, CronExpression, TimesTriggered, NextFireTime FROM CronTrigger WHERE id = :jobId];
            System.assertEquals(CRON_EXP, ct.CronExpression);
            System.assertEquals(0, ct.TimesTriggered);

        Test.stopTest();
    }
}

I have tried this test class and only got 17%
 

@istest
public with sharing class NoActivityThisQrtrTest {
    static testmethod void testSample() {
        Test.startTest();
        NoActivityThisQrtr obj = new NoActivityThisQrtr();
        obj.execute( null );
        Test.stopTest();
    }
}