Persisting a domain model with JDO 2.0 - POJOs in Action: Developing Enterprise Applications with Lightweight Frameworks - page 161

JDO does not define a standard way to access the O/R mapping, and so each method
delegates to a vendor-specific implementation of JDOMappingTestsStrategy :
public abstract class JDOMappingTests extends TestCase {
JDOMappingTestsStrategy strategy;
protected void assertClassMapped(Class type, String table) {
strategy.assertClassMapping(type, table);
}
protected void assertAllFieldsMapped() {
strategy.assertAllFieldsMapped();
}
…
}
Let's now look at JDOSchemaTests , which also delegates to a JDOMappingTests-
Strategy .
Overview of JDOSchemaTests
In addition to testing the O/R mapping, you must verify that the database schema
matches the mapping. JDOSchemaTests is a base class for writing this kind of test.
It defines an assertDatabaseSchema() method, which fails if the mapping refer-
ences tables or columns that are missing from the database schema. Because the
JDO specification does not provide a standard API for doing this, JDOSchemaTests
delegates to vendor-specific implementation of the JDOMappingTestsStrategy :
public class JDOSchemaTests extends TestCase {
JDOMappingTestsStrategy strategy;
protected void assertDatabaseSchema() throws Exception {
strategy.assertDatabaseSchema();
}
…
}
The assertDatabaseSchema() method simply delegates to the corresponding
method defined by the JDOMappingTestsStrategy . Let's see how this works.
JPOXMappingStrategy
ORMU nit encapsulates the vendor-specific API s behind the JDOMappingTests-
Strategy interface. There is a separate implementation of this interface for
each JDO implementation. Listing 5.1 shows an excerpt from the JPOX implemen-
tation of JDOMappingStrategy . The methods that make assertions about the O/R
mapping use JPOX' s metadata classes. They call the JPOX MetaDataParser , which