So, I re-wrote a lot of my code and am still having some issues. I suck at Test Classes

Trigger:

trigger AccountUpdateonLogCall on Task (after insert, after update) {
	
	//To do - If the Purpose of a completed task contains "Low Redemption" or "Proactive", put the description of the completed task in the 
	//the "Low_Redemption_Notes__c" and/or "Proactive_Communication_Notes__c" field on the account object

//Create a set of related account ID's
Set <ID> acctIDs = new Set <ID> ();


//For every task, add it's related to account ID to the set
	for (Task t: Trigger.new){
	  acctIDs.add(t.accountID);
//Create a map to match the task related to ID's with their corresponding account ID's
	  Map<ID, Account> acctMap = new Map<ID, Account> ([Select ID, Proactive_Communication_Notes__c, Low_Redemption_Notes__c  from Account where ID in :acctIDs]);
//Create the account object
      Account acctRec = acctMap.get(t.accountID);

//If the account ID isn't null, the subject line starts with "sw", and the task has been marked as completed    
	if ((t.accountID != null) &&(t.Purpose__c.Equals('Proactive Communication') ||t.Purpose__c.Equals('Low-Redemption Communication') ) && (t.Status == 'Completed'))
//Check to see if the which fields to update based upon the Purpose__c field.
  	  if (t.Purpose__c == 'Proactive Communication'){
//Update the Last_SW_Activity__c field on the account object with the task's end date  
  		  acctrec.Proactive_Communication_Notes__c = t.Description;
  		  update acctRec;
  	  }
  	  else if (t.Purpose__c == 'Low-Redemption Communication'){
  	  	  acctrec.Proactive_Communication_Notes__c = t.Description;
  	  	  acctrec.Low_Redemption_Notes__c = t.Description;
  		  update acctRec;
  	}
  }
}

 Test Class:

@isTest
private class TestClass {

    static testMethod void myUnitTest() {
        // TO DO: implement unit test
        
        Account a = new Account(name='Test');
        insert a;
        Account b = new Account(name='Test2');
        insert b;
        
 		       
        Task t = new Task(subject='Test Activity', Status = 'Completed', Purpose__c = 'Low-Redemption Communication', Description = 'I have Called This Dealership', whatId = a.id);
        insert t;
        Task t2 = new Task(subject='Test Activity', Status = 'Completed', Purpose__c = 'Proactive Communication', Description = 'I have Called This Dealership2', whatId = b.id);
        insert t2;
        test.startTest();
        
        a = [SELECT ID, Low_Redemption_Notes__c, Proactive_Communication_Notes__c  FROM Account WHERE ID = :a.id];
        b = [SELECT ID, Low_Redemption_Notes__c, Proactive_Communication_Notes__c  FROM Account WHERE ID = :b.id];
        System.assertEquals(t.Description, a.Low_Redemption_Notes__c);
        System.assertEquals(t.Description, a.Proactive_Communication_Notes__c);
        System.assertEquals(t.Description, b.Proactive_Communication_Notes__c);
 		test.stopTest();
    }
}

Issues: Still getting an Assertion Failure: t.description and a.Low_Redemption_Notes don't match.

Still not test coverage.

Can someone give me some assistance? Still a huge n00b