Hi All,

I am trying to write test class for a class which makes HTTP callout  and returns response in wrapper. Below is my code

//Callout Class. This is a blurpint please avaoid syntax error

public class CalloutClass {

@AuraEnabled
public static wrapperClass CalloutMethod (string wslr){   //This method returna a wrapper

wrapperClass wrapper =new wrapperClass();

Http h=new Http(); 
HttpRequest req=new HttpRequest();
/*
Request Params
*/

HttpResponse res=h.send(req);

/*
Deserialize response
*/

if(res.getStatusCode()==200){
wrapper.Status=res.getStatus();
wrapper.StatusCode=res.getStatusCode();
wrapper.response=res.getBody();

}

return wrapper;
}


public class wrapperClass{

@AuraEnabled public string Status {get; set;}
@AuraEnabled public integer StatusCode {get; set;}
@AuraEnabled public list<object> response {get; set;}
}


}

//Mock Class

@isTest
public class MockCallout implements HTTPCalloutMock {

Public HTTPResponse respond(HTTPRequest Req) {
    HTTPResponse Res=New HTTPResponse();
    
    Res.setStatusCode(200); 
    Res.setStatus('OK');    
    //Res.setBody(); //callout response is list of objects so dont know how to set response here without line break 
    return Res;    
    }


}

//Test Class

@isTest
Public Class OP_TestAppointmentCallout {

@isTest 
public Static void TestAppointmentData(){


   Test.setMock(HttpCalloutMock.class,new MockCallout());   

 
    CalloutClass.wrapperClass Wrapper=CalloutClass.CalloutMethod('93411');
    
    String Actualstatus =Wrapper.Status;
    Integer Actualstatuscode =Wrapper.StatusCode;
    
    
    system.assertEquals('OK',Actualstatus);
    system.assertEquals(200,Actualstatuscode);
   
    }

}

When i run test i am getting Null pointer exception for test class. I am not sure how to set fake response in mock class and how to call actuall class in test class. Please help