Hi,

   I have developed an apex class which displays the TargetDate of CaseMilestone related with a particular case.
   
The following is my Apex class:-

public class Clock {
Public String  casename {get;set;}
    public String getCaseMilestone() {
        return null;
    }


    public Clock() {
    }


List<CaseMilestone> sr = new List<CaseMilestone>();
List<CaseMilestone> srresponse = new List<CaseMilestone>();
ID myId;
public Datetime targetDate{get;set;}
public Datetime targetResponseDate{get;set;}

public Clock(ApexPages.StandardController controller) {
   myId = ApexPages.CurrentPage().getParameters().get('id');
  
   sr = [select TargetDate from CaseMilestone where CaseId =: myId and MilestoneTypeId ='557900000008Orj'];
srresponse = [Select TargetDate from CaseMilestone where CaseId =: myId and MilestoneTypeId ='557900000008OrU'];
  
   for(CaseMilestone s1 : sr)
   {
       targetDate  = s1.TargetDate;
    
   }
  
   for(CaseMilestone s2 : srresponse)
   {
       targetResponseDate  = s2.TargetDate;
      
   }
    }
}
    
  Now i need to write a test class for this class.  I have written a test class but it is not working. 

 The following is my test class

@isTest
private class CaseTest{
static testmethod void testLoadData(){
String caseJSON = '{"attributes":{"type":"CaseMilestone","url":"/services/data/v25.0/sobjects/CaseMilestone/55590000000CiTX"},"Id":"55590000000CiTX","MilestoneTypeId":"557900000008OrU","TargetDate":"5/30/2014 6:01 PM"}';
CaseMilestone c = (CaseMilestone) JSON.deserialize(caseJSON, CaseMilestone.class );
System.debug('Test case:' + c.TargetDate);
System.debug('Test caseId:' + c.Id);
System.debug('Test caseStatus:' + c.MilestoneTypeId);

CaseMilestone c1 = new CaseMilestone();
c1.Id = c.Id;
//c1.MilestoneTypeId = c.MilestoneTypeId;
//c1.TargetDate= c.TargetDate;
update c1;

//System.debug('Test caseStatus1:' + c1.status);
System.assertequals(c1.TargetDate,c.TargetDate);
}
}

This class saves but it doesnt cover anything [0% Code coverage].

I  have commented two lines of code in my above test class. This is because if i remove those comments then i get an compile error which states the "Field: CaseMilestone.MileStonetypeId is not a Writable Field". Same is the error with TargetDate field. It shows the error "Field: CaseMilestone.TargetDate is not a Writable Field". 

Pls help me tweak the code properly so that i get atleast Some code coverage. Why is this test class not covering any code. Why am i getting the Field not Writable error when i remove the comments.

If possible pls help me with the new code. Its really urgent. I need to Migrate data from one instance to another and i am lagging because of this. 

Awaiting for reply. Thanks a ton.