Test class for a schedulable batch is not firing the batch

For the life of me I cannot get this test class to work. It does not appear to be firing the batch class. Here is the code for the class:

global class csLastActivityBatch implements Schedulable {
    global void execute(SchedulableContext SC) {   
      List<Account> AccountToUpdate = new List<Account>();
      List<Account> acc = [Select Id,
                                  Last_CS_Activity__c
                                   from Account 
                                   where Type='Customer' or Type='Reseller Customer' ];
      List<User> usr = [Select Id,
                                  Department
                                   from User 
                                   where Department='Customer Success' ];
      Map<Id,Date> accountMap = new Map<Id,Date>();
      for(AggregateResult ar : [Select AccountId, max(StartDateTime) 
                           from Event
                           where AccountId IN: acc 
						   and OwnerId IN: usr
                           and StartDateTime <= Today     
                           group by AccountId]) 
 	  	{ 
        accountMap.put(String.valueOf(ar.get('AccountId')),Date.valueOf(ar.get('expr0')));
      	} 
      for(Id parentId: accountMap.keySet())  
  		{
        AccountToUpdate.add(new Account(Id = parentId, Last_CS_Activity__c = accountMap.get(parentId)));
  		}
     Update AccountToUpdate;
    }
}

and the test class

@isTest
private class testcsLastActivityBatch {
@isTest
    static void csActivityTestClass() 
    {    
        Profile pp = [SELECT Id FROM Profile WHERE Name='CS User'];
        User u = new User();
        u.email = 'username2099NQG@Ducoxyz.com';
        u.CompanyName = 'TEST';
        u.Lastname = 'Last';
        u.Department = 'Customer Success';
     	u.Title = 'title';
     	u.Alias = 'alias';
     	u.TimeZoneSidKey = 'America/Los_Angeles';
     	u.EmailEncodingKey = 'UTF-8';
     	u.LanguageLocaleKey = 'en_US';
     	u.LocaleSidKey = 'en_US';
        u.IsActive = true;
        u.username = 'username2099NQG@Ducoxyz.com';
        u.ProfileId = pp.Id;
        insert u; 
        Account a = new Account();
        a.Name = 'Test Account XYXY';
        a.BillingCountry = 'United Kingdom';
        a.BillingCity = 'London';
        a.Type = 'Customer';
        a.Segment__c = 'Bank';
        a.AnnualRevenue = 10;
        a.Last_CS_Activity__c = date.ValueOf('1968-09-20');
        insert a;
        Event t = new Event();
        t.Subject = 'Test Subject';
        t.ActivityDate = date.ValueOf('1968-09-22');
        t.WhatId = a.id;
        t.type = 'Client services Call';
        t.ActivityDateTime = datetime.newInstance(1968, 9, 22, 13, 30, 0);
	    t.DurationInMinutes = 60; 
        t.OwnerId = u.Id;
        insert t;
        t = [SELECT id, ActivityDate, OwnerId, AccountId, WhatId, StartDateTime FROM Event WHERE id= :t.id];  
        Update t;
        a = [SELECT id, Name, Last_CS_Activity__c, Type FROM Account WHERE id= :a.id];  
        Update a;
        Test.startTest();
        	csLastActivityBatch sh1 = new csLastActivityBatch();
        	String sch = '0 0 2 * * ?';
        	String jobId = system.schedule('Test Check', sch, sh1);
        	CronTrigger ct = [Select id , CronExpression, TimesTriggered from CronTrigger where id = :jobId];	
            System.assertEquals(sch,ct.CronExpression);
            System.assertEquals(0,ct.TimesTriggered);
        Test.stopTest();
        System.assertEquals(1,ct.TimesTriggered);
        System.assertEquals(a.Last_CS_Activity__c,t.ActivityDate);
    }   
}

Any help on gettiong it to run would be appreciated. The class itself works perfectly in the sandbox but I cannot get the test clas to work.