I have the following code and need to write a test for the constructor and the submitNotify method but am having a hard time trying to figure out how to do that since the server is set from a page parameter:

public with sharing class ServerNotificationsController {
	
    public Server__c server { get; set; } 
    public String notification {get; set;}
    public String emailBody {get; set;}
    public Boolean showFormPanel {get; set;}
    public Boolean showResultsPanel {get; set;}
    public String[] emailToList = new String[]{};     
    public String feedbackMessage {get; set;}
    public List<Contact> recipientsForDisplay = new List<Contact>{}; 
    
	
	public List<Contact> getRecipientsForDisplay() {
         return (List<Contact>) recipientsForDisplay;
    }
    
    public List<Account> accounts {
	  get {
	    if(accounts==null) {
	      accounts = [SELECT Id, (SELECT Id, Name, Email, Server_Down_Notification__c, Change_Control_Notification__c FROM Contacts) FROM Account WHERE Server__c = :server.Id AND Server__c != NULL];
	    }
	    return accounts;
	  }
	  private set;
	}
    
    private ApexPages.StandardController controller;   
	
	
	public ServerNotificationsController(ApexPages.StandardController controller) {
		this.controller = controller;
		if(server == null)
		{
			this.server = [select id, name from Server__c where id =
                       :ApexPages.currentPage().getParameters().get('id')];
		}
        this.showFormPanel = true; 
        notification = 'ServerDown';
        BuildSingleNotificationRecipientList();
	}
	
	
	 public PageReference submitNotify() {	 	
		if(emailToList.size() > 0)
		{
			Messaging.SingleEmailMessage mail = new Messaging.SingleEmailMessage();			
			String[] toAddresses = emailToList; 	
			mail.setToAddresses(toAddresses);			
			mail.setReplyTo('support@domain.com');
			mail.setSenderDisplayName('Support');
			
			mail.setSubject(notification + ' Notification - ' + server.Name);
			mail.setBccSender(false);
			mail.setUseSignature(false);
			
			mail.setPlainTextBody(emailBody);
			
			Messaging.sendEmail(new Messaging.SingleEmailMessage[] { mail });		
			
		}
	 	this.showFormPanel = false;
       		this.showResultsPanel = true;
       		 
            return null;
     }

}
     
  

I am thinking the test needs to run the code in the constructor but not sure how to set the id parameter on the page and does it need to be a real object id or one I create in the test:

static testMethod void testServerNotificationsController () {

ApexPages.StandardController tempController = new ApexPages.StandardController(tempServer);
ServerNotificationsController serverController = new ServerNotificationsController(tempController);
System.assert(serverController.server != null);
}