My Apex unit tests, which were all working in v23.0, are now failing in my v24.0 sandbox because there are no Pricebook2 records in the test database. I'm not sure how to fix this -- I've tried inserting my own Pricebook2 record but it doesn't make any difference, because it's not the Standard Price Book.

Here's my code, abbreviated:

Product2 newProd = new Product2(Name = 'test product', family = 'test family');
insert newProd;

PriceBookEntry pbEntry = new PriceBookEntry(
    UnitPrice = 300,
    PriceBook2Id = [select id from PriceBook2 where isStandard = true].Id,
    Product2Id = newProd.Id
);

 The query on line 6 fails with "List has no rows". But if I try this instead:

Product2 newProd = new Product2(Name = 'test product', family = 'test family');
insert newProd;

PriceBook2 pb = new PriceBook2(Name = 'test price book');
insert pb;

PriceBookEntry pbEntry = new PriceBookEntry(
    UnitPrice = 300,
    PriceBook2Id = pb.Id,
    Product2Id = newProd.Id
);

insert pbEntry;

 Then the last line fails with a STANDARD_PRICE_NOT_DEFINED exception.

Not sure how to get around this -- my understanding is that this code has stopped working in v24.0 because unit tests no longer have access to real data. How does one test opportunity line items, then?