2 * Copyright 2005-2010 the original author or authors.
4 * Licensed under the Apache License, Version 2.0 (the "License");
5 * you may not use this file except in compliance with the License.
6 * You may obtain a copy of the License at
8 * http://www.apache.org/licenses/LICENSE-2.0
10 * Unless required by applicable law or agreed to in writing, software
11 * distributed under the License is distributed on an "AS IS" BASIS,
12 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
13 * See the License for the specific language governing permissions and
14 * limitations under the License.
18 * This package provides test library for database testing in general and JPA testing
19 * specifically. As part of this it provides a means to transparently start an inmemory
20 * database from a junit test or connect to an external database. Also, given a persistence
21 * unit it is easy to start testing it in a junit test with only a few lines of code.
25 * The main use cases are explained below:
28 * <li> <a href="#db-basic">Basic database testing, transparently connecting to a database</a>
30 * <li> <a href="#db-basic-external">Connecting to an external database</a>
32 * <li> <a href="#db-utils">Executing code within a JDBC transaction</a>
34 * <li> <a href="#db-unit">Using DB Unit in your tests</a>
36 * <li> <a href="#db-jpa-basic">Basic JPA testing</a>
38 * <li> <a href="#db-jpa-plus-jdbc">JPA testing combined with JDBC and DBUnit</a>
40 * <li> <a href="#db-jpa-services">Testing a service that requires a transaction</a>
42 * <li> <a href="#db-user-transaction">Controlling transactions through a <code>UserTransaction</code></a>
47 * See also the <a href="#design-overview">design overview</a>.
51 * <h2>Basic database testing, transparently connecting to a database</h2>
53 * Starting the database:
55 * Database db = DatabaseBuilder.getDatabase();
56 * DataSource dataSource = db.start();
59 * If nothing is specified in the user's environment, an inmemory database is started (derby).
60 * Using the datasource is just standard JDBC now.
63 * After a test it is good practice to stop the database:
69 * <a name="db-basic-external">
70 * <h2>Connecting to an external database</h2>
73 * Connecting to an external database can be done by requiring the 'external' capability on
74 * the database provider.
76 * Database db = DatabaseBuilder.getDatabase(DatabaseProvider.CAPABILITY_EXTERNAL);
78 * This also requires a number of environment variables or system properties to be set,
79 * see {@link ExternalDatabase}.
82 * However, the most convenient way to set the capabilities is usually to set a system property or environment
83 * variable see the javadocs of {@link DatabaseBuilder}. and
84 * specifically <code>DatabaseBuilder.DB_CAPABILITIES_PROP</code>
89 * <h2>Executing code within a JDBC transaction</h2>
92 * To execute code withing a JDBC transaction, use the {@link DatabaseUtils} and
93 * use the {@link DatabaseUtils#executeInTransaction(org.wamblee.support.persistence.DatabaseUtils.JdbcUnitOfWork)}
97 * DatabaseUtils dbutils = new DatabaseUtils(dataSource);
98 * boolean result = dbutils.executeInTransaction(
99 * new JdbcUnitOfWork<Boolean>() {
101 * public Boolean execute(Connection aConnection) throws Exception {
102 * ResultSet res = jpaTester.getDbUtils().executeQuery(
103 * aConnection, GROUP_QUERY, aGroup);
108 * {@link DatabaseUtils} also provides various other utility methods to work with JDBC queries.
111 * <h2>Using DB Unit in your tests</h2>
114 * <p>To work with <a href="http://dbunit.org">DBUnit</a>,
115 * <code>DatabaseUtils#createDbTester(org.dbunit.dataset.filter.ITableFilterSimple)</code>
116 * must be used passing it in the tables to use in the form of a {@link org.dbunit.dataset.filter.ITableFilterSimple}
120 * IDatabaseTester dbtester = dbutils.createDbTester(new ITableFilterSimple() {
121 * public boolean accept(String aTableName) throws DataSetException {
122 * return aTableName.startsWith("XYZ_");
127 * <p>The reason for using a <code>DatabaseUtils</code> instead of DBUnit directly is that
128 * <code>DatabseUtils</code> will keep track of connections and close them when <code>DatabaseUtils</code>
131 * <a name="db-jpa-basic">
132 * <h2>Basic JPA testing</h2>
135 * First step is to create a {@link PersistenceUnitDescription} that matches the persistence unit you
138 * <p>Second step is to make sure that all entities are listed explicitly in your
139 * <code>persistence.xml</code>. Currently, class path scanning appears to fail when
141 * Specifying all entities explicitly is not necessarily a bad thing as it is also more efficient.
145 * Now create a <code>JpaTester</code> in your test code:
149 * public void setUp() throws Exception {
151 * // First we create the JpaTester by telling us which persistence unit we
152 * // are going to test
153 * jpaTester = new JpaTester(new MyPersistenceUnit());
159 * Then in test code execute some JPA code within a unit of work:
162 * jpaTester.getJpaBuilder().execute(new JpaUnitOfWork<Void>() {
163 * public Void execute(EntityManager aEm) {
164 * MyEntity entity = new MyEntity("a", "b");
165 * aEm.persist(entity);
172 * Note that in addition to this method it is also possible to directly control transactions
173 * through {@link JpaBuilder#begin()}, {@link JpaBuilder#commit(javax.persistence.EntityManager)},
174 * and {@link JpaBuilder#rollback(javax.persistence.EntityManager)}.
177 * <a name="db-jpa-plus-jdbc">
178 * <h2>JPA testing combined with JDBC and DBUnit</h2>
180 * <p>The <code>JPATester</code> provides access to all required object. It is usually convenient to
181 * get them directly from the <code>JPATester</code> after initializing it:
183 * builder = jpaTester.getJpaBuilder();
184 * dbutils = jpaTester.getDbUtils();
185 * dbtester = dbutils.createDbTester(new MyTables());
188 * <a name="db-jpa-services">
189 * <h2>Testing a service that requires a transaction</h2>
192 * <p>Using {@link TransactionProxyFactory} it is possible to create a proxy for a given
193 * service interface to provide the semantics of 'requires new' transaction semantics.
195 * TransactionProxyFactory<Service> factory = new TransactionProxyFactory<Service>(
196 * jpaTester.getJpaBuilder(), Service.class);
197 * Service service = new ServiceImpl(factory.getTransactionScopedEntityManager());
198 * Service proxy = factory.getProxy(service);
199 * proxy.execute(...);
203 * In the above example, the <code>Service</code> POJO requires an {@link EntityManager} in its
204 * constructor and it is passed a transaction scoped entitymanager from the factory. This entitymanager
205 * is in fact a so-called contextual reference.
206 * Next, the proxy is obtained from the factory. Invoking any method on it will make sure a new
207 * transaction is started and a new entity manager is created for the scope of that transaction.
210 * <a name="db-user-transaction">
211 * <h2>Controlling transactions through a <code>UserTransaction</h2>
215 * It is also possible to manage JPA transaction through a <code>UserTransaction</code>.
216 * This is mostly useful if you are test software that uses <code>UserTransaction</code> for
217 * managing transactions, or if you want to manage multiple transactional resources.
218 * See the explanation at {@link org.wamblee.test.transactions.SimpleTransactionManager} for more details.
221 * <a name="design-overview">
222 * <h2>Design overview</h2>
225 * <h3>Database transparency</h3>
228 * <img src="doc-files/Class_Diagram__org.wamblee.support.persistence__database.jpg"
232 * {@link DatabaseProvider} uses <code>java.util.ServiceLoader</code> to find all implementations
233 * of {@link DatabaseProvider} on the classpath. It then asks the database providers whether
234 * they support the required capabilities (by default inmemory), and the first provider that
235 * supports the capabilities is used to create the database.
238 * Note that the <code>Database</code> interface is not intended to always create a database.
239 * It will do so for {@link DerbyDatabase} (inmemory), but with {@link ExternalDatabase}
240 * it simply connects to an external database based on system properties or environment
244 * <h3>JPA tester overview</h3>
247 * <img src="doc-files/Class_Diagram__org.wamblee.support.persistence__jpatester.jpg"
251 * <p><code>JPATester</code> is responsible for:</p>
253 * <li> Starting or connecting to a database, using {@link DatabaseBuilder}.
255 * <li> Registering the acquired datasource in JNDI by first stubbing JNDI
256 * using {@link org.wamblee.support.jndi.StubInitialContextFactory}.
258 * <li> Creating the {@link JPABuilder} that will do the JPA heavy lifting.
260 * <li> Creating the {@link DatabaseUtils} for JDBC and DBUnit testing.
266 package org.wamblee.test.persistence;