The various adapters are now available via the
dm-xxx-adapter repos below the datamapper account
on github.

The auto_migrate!/auto_upgrade! functionality is
now only available in case dm-migrations gets
required. In order to get a datamapper application
up and running along with automigrations,
do the following:

  require 'dm-core' #optional
  require 'dm-migrations'
  DataMapper.setup(:default, 'mysql://localhost/fu')
  # model definitions ...
  DataMapper.auto_migrate!

Failing to require dm-migrations will result in

  undefined method `auto_migrate!'
  for DataMapper:Module (NoMethodError)

From this commit on, dm-core does not provide any
adapters apart from the abstract and in_memory
adapters.

This means that from now on, users will need to
depend on any of the datamapper/dm-xxx-adapter gems
in order to be able to connect to the database of
their choice. If automigration facilities are
desired, it's necessary to also depend on and require
dm-migrations.

Unfortunately, the way dm-core's shared adapter
specs are currently written doesn't lend itself
nicely to the way we want to use them from the
various extracted dm-xxx-adapters. Because we
lazily require the desired adapter only when
DataMapper.setup is called, we cannot require the
shared examples before doing so. This is because
the shared adapter spec relies on the adapter
class to already be known at the time it gets
read in. It relies on that because it checks if
the various adapter methods like :create, :update
etc are supported by the adapter under test. To
workaround this, you can use

  ADAPTER_SUPPORTS=all bundle exec rake spec

to run specs for the various dm-xxx-adapter gems.
A proper fix for this issue would be to write the
shared adapter specs in such a way, that they
evaluate the adapter possibilities only at runtime
and not immediately when the file gets read in.