write test class for htttp request

Help to write test class for htttp request I can’t figure it out
public with sharing class currencyRates {
@AuraEnabled
public static List<Object> getRates(){
String requestData=’https://www.nbrb.by/api/exrates/rates?periodicity=0′;
Http http =new Http();
HttpRequest request = new HttpRequest();
request.setEndPoint(requestData);
request.setMethod(‘GET’);
HttpResponse response = http.send(request);
List<Object> result =null;
if(response.getStatusCode()==200){
result =(List<Object>)JSON.deserializeUntyped(response.getBody());
}else{
ApexPages.Message mes =new ApexPages.Message(ApexPages.Severity.ERROR,’There was an error in reading Data’);
}
return result;
}
}