Persisting a domain model with JDO 2.0 - POJOs in Action: Developing Enterprise Applications with Lightweight Frameworks - page 174

delivery address and time using the Spring and JDO API s. First, we write some
mock object tests for RestaurantRepository . After that we write the method
and get the mock objects test to pass. Finally, we write some database tests for the
JDO query that is executed by RestaurantRepository to find the restaurants.

5.3.1 Writing a mock object test for findRestaurants()

The mock objects test for findRestaurants() uses mock objects to verify that it
calls the Spring and JDO API s correctly. But to know which objects to mock we
must decide how findRestaurants() executes the query. It can use either a
named query or a query that is embedded in the code. In this particular case it
makes sense to use a named query because, as you will see shortly, the query is too
large to embed inside Java code. It would be spread over several lines of code,
which would be messy.

Executing a named query using a callback class
A repository could execute a query by calling the JDO API s directly, but it is usually
much easier to use the JdoTemplate class. It implements boilerplate code that
you would otherwise have to write and provides a number of convenience meth-
ods. However, at the time of this writing one limitation of the JdoTemplate class
is that it lacks a convenience method for executing named queries with parame-
ters. We must instead use it to execute a JdoCallback that creates and executes
the named query. Even though this requires more code than calling a conve-
nience method, it is still simpler than using the JDO API s directly because the
JdoTemplate takes care of opening and closing the PersistenceManager and
mapping exceptions thrown by JDO to Spring data access exceptions.
The most straightforward and commonly used way to use a JdoTemplate to
execute a JdoCallback is to use an anonymous class. But one big problem with
using an anonymous callback is that it's impossible for a mock JdoTemplate to
verify that execute() is called with the correct JdoCallback object. A better
approach is to use a named JdoCallback class that implements the equals()
method because we would then be able to configure a mock JdoTemplate .
To implement the findRestaurants() method, we can define a JdoCall-
back class called ExecuteNamedQueryWithMapCallback whose constructor takes
as parameters the name of the query and the Map containing the query's parame-
ters. This class, shown in listing 5.4, creates the named query and returns the
result of executing it by calling Query.executeWithMap() . It has an equals()
method that returns true if the query names and parameters are the same in the
two objects.