+ * This package provides test library for database testing in general and JPA testing + * specifically. As part of this it provides a means to transparently start an inmemory + * database from a junit test or connect to an external database. Also, given a persistence + * unit it is easy to start testing it in a junit test with only a few lines of code. + *
* - * The following utilities are available: + *+ * The main use cases are explained below: + *
*JpaTester that provides a callback based
- * style of working with transaction-scoped entity managers.
+ * JpaTester for working with databases in general. Test code will not use this
- * utility often.
+ * JpaTester
+ * JpaTester
+ * + * See also the design overview. + *
+ * + * + *+ * Database db = DatabaseBuilder.getDatabase(); + * DataSource dataSource = db.start(); + *+ *
+ * If nothing is specified in the user's environment, an inmemory database is started (derby). + * Using the datasource is just standard JDBC now. + *
+ *+ * After a test it is good practice to stop the database: + *
+ *+ * db.stop(); + *+ * + * + *
+ * Database db = DatabaseBuilder.getDatabase(DatabaseProvider.CAPABILITY_EXTERNAL); + *+ * This also requires a number of environment variables or system properties to be set, + * see {@link ExternalDatabase}. + * + *
+ * However, the most convenient way to set the capabilities is usually to set a system property or environment
+ * variable see the javadocs of {@link DatabaseBuilder}. and
+ * specifically DatabaseBuilder.DB_CAPABILITIES_PROP
+ *
+ * To execute code withing a JDBC transaction, use the {@link DatabaseUtils} and + * use the {@link DatabaseUtils#executeInTransaction(org.wamblee.support.persistence.DatabaseUtils.JdbcUnitOfWork)} + * method. + *
+ *
+ * DatabaseUtils dbutils = new DatabaseUtils(dataSource);
+ * boolean result = dbutils.executeInTransaction(
+ * new JdbcUnitOfWork<Boolean>() {
+ * @Override
+ * public Boolean execute(Connection aConnection) throws Exception {
+ * ResultSet res = jpaTester.getDbUtils().executeQuery(
+ * aConnection, GROUP_QUERY, aGroup);
+ * return res.next();
+ * }
+ * });
+ *
+ * {@link DatabaseUtils} also provides various other utility methods to work with JDBC queries.
+ *
+ *
+ * To work with DBUnit,
+ * DatabaseUtils#createDbTester(org.dbunit.dataset.filter.ITableFilterSimple)
+ * must be used passing it in the tables to use in the form of a {@link org.dbunit.dataset.filter.ITableFilterSimple}
+ * object.
+ * IDatabaseTester dbtester = dbutils.createDbTester(new ITableFilterSimple() {
+ * public boolean accept(String aTableName) throws DataSetException {
+ * return aTableName.startsWith("XYZ_");
+ * }
+ * });
+ *
+ *
+ * The reason for using a DatabaseUtils instead of DBUnit directly is that
+ * DatabseUtils will keep track of connections and close them when DatabaseUtils
+ * is closed
+ * First step is to create a {@link PersistenceUnitDescription} that matches the persistence unit you + * want to test. + *
+ *Second step is to make sure that all entities are listed explicitly in your
+ * persistence.xml. Currently, class path scanning appears to fail when
+ * run from junit.
+ * Specifying all entities explicitly is not necessarily a bad thing as it is also more efficient.
+ *
+ * Now create a JpaTester in your test code:
+ *
+ * @Before
+ * public void setUp() throws Exception {
+ *
+ * // First we create the JpaTester by telling us which persistence unit we
+ * // are going to test
+ * jpaTester = new JpaTester(new MyPersistenceUnit());
+ * jpaTester.start();
+ * }
+ *
+ *
+ * + * Then in test code execute some JPA code within a unit of work: + *
+ *+ * jpaTester.getJpaBuilder().execute(new JpaUnitOfWork+ * + * + *() { + * public Void execute(EntityManager aEm) { + * MyEntity entity = new MyEntity("a", "b"); + * aEm.persist(entity); + * return null; + * } + * }); + *
The JPATester provides access to all required object. It is usually convenient to
+ * get them directly from the JPATester after initializing it:
+ *
+ * builder = jpaTester.getJpaBuilder(); + * dbutils = jpaTester.getDbUtils(); + * dbtester = dbutils.createDbTester(new MyTables()); + *+ * + * + *
Using {@link TransactionProxyFactory} it is possible to create a proxy for a given + * service interface to provide the semantics of 'requires new' transaction semantics. + *
+ * TransactionProxyFactory+ * + *factory = new TransactionProxyFactory ( + * jpaTester.getJpaBuilder(), Service.class); + * Service service = new ServiceImpl(factory.getTransactionScopedEntityManager()); + * Service proxy = factory.getProxy(service); + * proxy.execute(...); + *
+ * In the above example, the Service POJO requires an {@link EntityManager} in its
+ * constructor and it is passed a transaction scoped entitymanager from the factory. This entitymanager
+ * is in fact a so-called contextual reference.
+ * Next, the proxy is obtained from the factory. Invoking any method on it will make sure a new
+ * transaction is started and a new entity manager is created for the scope of that transaction.
+ *
+ *
+ *
+ * {@link DatabaseProvider} uses java.util.ServiceLoader to find all implementations
+ * of {@link DatabaseProvider} on the classpath. It then asks the database providers whether
+ * they support the required capabilities (by default inmemory), and the first provider that
+ * supports the capabilities is used to create the database.
+ *
+ * Note that the Database interface is not intended to always create a database.
+ * It will do so for {@link DerbyDatabase} (inmemory), but with {@link ExternalDatabase}
+ * it simply connects to an external database based on system properties or environment
+ * variables.
+ *
+ *
+ *
+ * JPATester is responsible for: