Scott Gray wrote: > Hi Adam, > > I'm no transaction expert but how sure are we that starting a new > transaction just before each test and rolling it back at the end won't > work? From what I can gather Derby does actually alter the database > prior to committing the transaction but it also creates log records > that allow the changes to undone in case of a rollback. > > I just tried it using the JUnitListener class to start and end a > transaction and I can't see any obvious negative effects (aside from > tests failing that relied on data created in previous tests).
The reason that won't work, is that some services are configured to run in a *separate* transaction, completely separate from the one that is in the current thread. In those cases, the current transaction is suspended, then resumed. To do the transaction rollback stuff in those cases, becomes rather more complex. It's just simpler to save the disk files, and revert them all, between tests. Just need to make certain any background threads are restarted/shutdown.
