@isTest
public class TestDataFactory {
    public static void createTestRecords(Integer numAccts, Integer numContactsPerAcct) {
        List<Account> accts = new List<Account>();
        
        for(Integer i=0;i<numAccts;i++) {
            Account a = new Account(Name='TestAccount' + i);
            accts.add(a);
        }
        insert accts;
        
        List<Contact> cons = new List<Contact>();
        for (Integer j=0;j<numAccts;j++) {
            Account acct = accts[j];            
            // For each account just inserted, add contacts
            for (Integer k=numContactsPerAcct*j;k<numContactsPerAcct*(j+1);k++) {
                cons.add(new Contact(firstname='Test'+k,
                                     lastname='Test'+k,
                                     AccountId=acct.Id));
            }
        }
        // Insert all contacts for all accounts
        insert cons;
    }
}

@isTest
public class TestDataFactory {

    public static Invoice_Statement__c createOneInvoiceStatement(
                                                 Boolean withLineItem) { 
        // Create one invoice statement
        Invoice_Statement__c testInvoice = createInvoiceStatement();    
        
        if (withLineItem == true) {
            // Create a merchandise item
            Merchandise__c m = createMerchandiseItem('Orange juice');
            // Create one line item and associate it with the invoice statement.        
            AddLineItem(testInvoice, m);
        }                   
        
        return testInvoice;
    }            
    
    // Helper methods
    //
    private static Merchandise__c createMerchandiseItem(String merchName) {
        Merchandise__c m = new Merchandise__c(
            Name=merchName,
            Description__c='Fresh juice',
            Price__c=2,
            Total_Inventory__c=1000);
        insert m;
        return m;
    }
    
    private static Invoice_Statement__c createInvoiceStatement() {        
        Invoice_Statement__c inv = new Invoice_Statement__c(                
            Description__c='Test Invoice');      
        insert inv;
        
        return inv;
    } 
    
    private static Line_Item__c AddLineItem(Invoice_Statement__c inv, 
                                            Merchandise__c m) {
        Line_Item__c lineItem = new Line_Item__c(
                                    Invoice_Statement__c = inv.Id, 
                                    Merchandise__c = m.Id, 
                                    Unit_Price__c = m.Price__c, 
                                    Units_Sold__c = (Double)(10*Math.random()+1));
        insert lineItem;
        
        return lineItem;
    }       
}