I've been looking at all the examples for writing Test Methods and I keep coming across problems trying to write one for my class.  I'm enclosing the code below.  I would appreciate any help that can be provided on how to write test methods for this.

 

 

public class QuoteExtension {
    Integer LineCount = 0;
    
    public Opportunity Truck { get; private set; }  
    Double Truck_Subtotal = 0;
    
    public Opportunity Accessories { get; private set; }  
    Double Accessories_Subtotal = 0;
    
    public Opportunity CasedHole { get; private set; }  
    Double CasedHole_Subtotal = 0;

    public Opportunity OpenHole { get; private set; }  
    Double OpenHole_Subtotal = 0;
    
    public void Increment() {
        LineCount++;
    }

     public static testMethod void testQuoteExtenstion() {

        
    }
    
    
    public QuoteExtension(ApexPages.StandardController stdController) {
        ID id = ApexPages.CurrentPage().getParameters().get('id');
        Integer i = 0;
        
        /***** Begin Truck Section *****/
        
        Truck = [SELECT o.Id, o.Name, o.Amount, (SELECT op.Quantity, op.UnitPrice, op.TotalPrice,
            op.PricebookEntry.Name, op.OpportunityId, op.PricebookEntry.ProductCode,
            op.PricebookEntry.Product2.Family
            FROM OpportunityLineItems op WHERE op.PricebookEntry.Product2.Family = 'Truck')
            FROM Opportunity o where Id = :id];
        
            for(i=0;i<Truck.opportunityLineItems.size();i++) {
                Truck_Subtotal += Truck.opportunityLineItems[i].TotalPrice;
            }


        i = 0;
        /***** End Truck Section *****/
        
        /***** Begin Accessories Section *****/
        
        Accessories = [SELECT o.Id, o.Name, o.Amount, (SELECT op.Quantity, op.UnitPrice, op.TotalPrice,
            op.PricebookEntry.Name, op.OpportunityId, op.PricebookEntry.ProductCode,
            op.PricebookEntry.Product2.Family
            FROM OpportunityLineItems op WHERE op.PricebookEntry.Product2.Family = 'Accessories')
            FROM Opportunity o where Id = :id];
            
        for(i=0;i<Accessories.opportunityLineItems.size();i++) {
            Accessories_Subtotal += Accessories.opportunityLineItems[i].TotalPrice;
        }
        i = 0;
        
       /***** End Accessories Section *****/
        
        /***** Begin CasedHole Section *****/
        
        CasedHole = [SELECT o.Id, o.Name, o.Amount, (SELECT op.Quantity, op.UnitPrice, op.TotalPrice,
            op.PricebookEntry.Name, op.OpportunityId, op.PricebookEntry.ProductCode,
            op.PricebookEntry.Product2.Family
            FROM OpportunityLineItems op WHERE op.PricebookEntry.Product2.Family = 'Cased Hole')
            FROM Opportunity o where Id = :id];
        
        for(i=0;i<CasedHole.opportunityLineItems.size();i++) {
            CasedHole_Subtotal += CasedHole.opportunityLineItems[i].TotalPrice;
        }
        i = 0;
        /***** End CasedHole Section *****/

        /***** Begin OpenHole Section *****/
        
        OpenHole = [SELECT o.Id, o.Name, o.Amount, (SELECT op.Quantity, op.UnitPrice, op.TotalPrice,
            op.PricebookEntry.Name, op.OpportunityId, op.PricebookEntry.ProductCode,
            op.PricebookEntry.Product2.Family
            FROM OpportunityLineItems op WHERE op.PricebookEntry.Product2.Family = 'Open Hole')
            FROM Opportunity o where Id = :id];
        
        for(i=0;i<OpenHole.opportunityLineItems.size();i++) {
            OpenHole_Subtotal += OpenHole.opportunityLineItems[i].TotalPrice;
        }
        i = 0;
        /***** End OpenHole Section *****/
    }

    public Double Gettruck_subtotal() {
        return Truck_Subtotal;
    }
    public Double Getaccessories_subtotal() {
        return Accessories_Subtotal;
    }
    public Double Getcasedhole_subtotal() {
        return CasedHole_Subtotal;
    }
    public Double Getopenhole_subtotal() {
        return OpenHole_Subtotal;
    }

    public String Gettruck_style() {
        if(Truck_Subtotal == 0) {
            return 'style="display:none;"';
        } else {
            return '';
        }
    }    
    public String Getaccessories_style() {
        if(Accessories_Subtotal == 0) {
            return 'style="display:none;"';
        } else {
            return '';
        }
    }
    public String Getcasedhole_style() {
        if(CasedHole_Subtotal == 0) {
            return 'style="display:none;"';
        } else {
            return '';
        }
    }
    public String Getopenhole_style() {
        if(OpenHole_Subtotal == 0) {
            return 'style="display:none;"';
        } else {
            return '';
        }
    }
    
    public Integer Getlinecount() {
        Increment();
        return LineCount;
    }
}