Like Resources, Containers can also be declared via InitialContext properties as well. The most useful is to declare a Stateful SessionBean container so that it's guaranteed to passivate and activate on each call to the bean, allowing you to test your callbacks behave as you need them to.
Properties p = new Properties();
p.put(Context.INITIAL_CONTEXT_FACTORY, "org.apache.openejb.core.LocalInitialContextFactory");
p.put("myStatefulContainer", "new://Container?type=STATEFUL");
p.put("myStatefulContainer.PoolSize", "0");
p.put("myStatefulContainer.BulkPassivate", "1");
Context context = new InitialContext(p);
Note, this only works when using the LocalInitialContextFactory to embed OpenEJB into the vm. Once embedded, further configuration properties are ignored.
See Containers and Resources for a full list of supported Resource types and their properties.