Yes, you can create one big TestClass but you cant create one test for all your extension unless you create a dynamic visualforce page and controller. That is another topic that you might want to look into, but it takes a lot of work and understanding all the dynamic controller stuff.

k, thank you for your time Eric. I really appreciate it you legend.

So sorry to bother you again buddy...but I was wondering if you could give me a hand with writing a test for my attachmentAccount extension...I can only get 52%. Don't feel obligated, only if you have time.

Test:

@istest

private class TestAccountExtension{

static testMethod void TestAccountExtension() {
Account acc = new Account(Name = 'Test Att Account');
insert acc;
Attachment attachment = new Attachment();
attachment.Name = 'Unit Test Attachment';
attachment.Body = Blob.valueOf('Unit Test Attachment Body');
attachment.parentId = acc.id;
Insert attachment;


//Create the controller
ApexPages.StandardController sc = new ApexPages.StandardController(acc);

//Create the instances of the controller
AccountExtension myPageTest = new AccountExtension();

AccountExtension myPageTestSC = new AccountExtension(sc);
myPageTestSC.save();
}
}

Extension:

public class AccountExtension
{
private final Account webAccount;
public AccountExtension(ApexPages.StandardController stdController)
{
webAccount = (Account)stdController.getRecord();
attach = new Attachment();
}


public AccountExtension(){}
public PageReference saveAccount()
{
PageReference p= new PageReference('/apex/DestinyAccount?id='+webAccount.Id+'&sfdc.override=1');
p.setRedirect(true);
p.getParameters().put('tab','Attachments');
return p;
}
public PageReference save()
{
 PageReference p= new PageReference('/apex/DestinyAccount?id='+webAccount.Id+'&sfdc.override=1');
p.setRedirect(true);
p.getParameters().put('tab','Attachments');
update webAccount;
upload();
return p;
}
public String parentId {get;set;}
public Attachment attach {get;set;}
public ApexPages.Pagereference upload()
{
attach.ParentId = webAccount.Id;
insert attach;
return new ApexPages.Standardcontroller(attach).view();
}

}

 Thank you in advance