I want to write test class for this Email Service apex class

global class ResourceToLeave implements Messaging.InboundEmailHandler {

  global Messaging.InboundEmailResult handleInboundEmail(Messaging.inboundEmail email,
                                                       Messaging.InboundEnvelope env){

    // Create an InboundEmailResult object for returning the result of the
    // Apex Email Service
    Messaging.InboundEmailResult result = new Messaging.InboundEmailResult();
   
    String[] emailBody = email.plainTextBody.split('\n', 0);
   
    String startdate = emailBody[0].substring(10);
    String[] tempStr = startdate.split('/');
    Integer d = Integer.valueOf(tempStr[0]);
    Integer m = Integer.valueOf(tempStr[1]);
    Integer y = Integer.valueOf(tempStr[2]);
    Date sdt = Date.newInstance(y,m,d);
   
    String enddate = emailBody[1].substring(8);
    String[] tempStr1 = enddate.split('/');
    Integer dd = Integer.valueOf(tempStr1[0]);
    Integer mm = Integer.valueOf(tempStr1[1]);
    Integer yy = Integer.valueOf(tempStr1[2]);
    Date edt = Date.newInstance(yy,mm,dd);
      
    // New Leave object to be created
    Leave__c[] leave = new Leave__c[0];
  
    // Try to look up any contacts based on the email from address
    // If there is more than one contact with the same email address,
    // an exception will be thrown and the catch statement will be called.
    try {
      Resource__c[] resource = [SELECT Id, Name FROM Resource__c WHERE Name = :email.subject LIMIT 1];
     
      Resource__c res;
      if(resource.size()>0)
      {
          res=resource[0];
      }
      // Add a new Task to the contact record we just found above.
      leave.add(new Leave__c(Resource__c=res.Id,
                             Start_Date__c=sdt,
                             End_Date__c=edt
                             ));
    
     // Insert the new Leave
     insert leave;   
    
     System.debug('New Leave Object: ' + leave );  
    }
    // If an exception occurs when the query accesses
    // the contact record, a QueryException is called.
    // The exception is written to the Apex debug log.
   catch (System.QueryException e) {
       System.debug('Query Issue: ' + e);
   }
  
   // Set the result to true. No need to send an email back to the user
   // with an error message
   result.success = true;
  
   // Return the result for the Apex Email Service
   return result;
  }
}