How to configure JPA for testing in Maven

Is there a way to set up a second persistence.xml file in a Maven project such that it is used for testing instead of the normal one that is used for deployment?

I tried putting a persistence.xml into src/test/resources/META-INF, which gets copied into target/test-classes/META-INF, but it seems target/classes/META-INF (the copy from the src/main/resources) gets preferred, despite mvn -X test listing the classpath entries in the right order:

[DEBUG] Test Classpath :
[DEBUG]   /home/uqpbecke/dev/NetBeansProjects/UserManager/target/test-classes
[DEBUG]   /home/uqpbecke/dev/NetBeansProjects/UserManager/target/classes
[DEBUG]   /home/uqpbecke/.m2/repository/junit/junit/4.5/junit-4.5.jar
...

I would like to be able to run tests against a simple hsqldb configuration without having to change the deployment version of the JPA configuration, ideally straight after project checkout without any need for local tweaking.

The following will work for Maven 2.1+ (prior to that there wasn't a phase between test and package that you could bind an execution to).

You can use the maven-antrun-plugin to replace the persistence.xml with the test version for the duration of the tests, then restore the proper version before the project is packaged.

This example assumes the production version is src/main/resources/META-INF/persistence.xml and the test version is src/test/resources/META-INF/persistence.xml, so they will be copied to target/classes/META-INF and target/test-classes/META-INF respectively.

It would be more elegant to encapsulate this into a mojo, but as you're only copying a file, it seems like overkill.

<plugin>
  <artifactId>maven-antrun-plugin</artifactId>
  <version>1.3</version>
  <executions>
    <execution>
      <id>copy-test-persistence</id>
      <phase>process-test-resources</phase>
      <configuration>
        <tasks>
          <!--backup the "proper" persistence.xml-->
          <copy file="${project.build.outputDirectory}/META-INF/persistence.xml" tofile="${project.build.outputDirectory}/META-INF/persistence.xml.proper"/>
          <!--replace the "proper" persistence.xml with the "test" version-->
          <copy file="${project.build.testOutputDirectory}/META-INF/persistence.xml" tofile="${project.build.outputDirectory}/META-INF/persistence.xml"/>
        </tasks>
      </configuration>
      <goals>
        <goal>run</goal>
      </goals>
    </execution>
    <execution>
      <id>restore-persistence</id>
      <phase>prepare-package</phase>
      <configuration>
        <tasks>
          <!--restore the "proper" persistence.xml-->
          <copy file="${project.build.outputDirectory}/META-INF/persistence.xml.proper" tofile="${project.build.outputDirectory}/META-INF/persistence.xml"/>
        </tasks>
      </configuration>
      <goals>
        <goal>run</goal>
      </goals>
    </execution>
  </executions>
</plugin>

In an EE6/CDI/JPA project, a test src/test/resources/META-INF/persistence.xml is picked up just fine without any further configuration.

When using JPA in Spring, the following works in the application context used for testing:

<bean id="entityManagerFactory"
    class="org.springframework.orm.jpa.LocalContainerEntityManagerFactoryBean">
    <property name="dataSource" ref="dataSource" />
    <!--
        JPA requires META-INF/persistence.xml, but somehow prefers the one
        in classes/META-INF over the one in test-classes/META-INF. Spring
        to the rescue, as it allows for setting things differently, like by
        referring to "classpath:persistence-TEST.xml". Or, simply referring
        to "META-INF/persistence.xml" makes JPA use the test version too: 
    -->
    <property name="persistenceXmlLocation" value="META-INF/persistence.xml" />

    <!-- As defined in /src/test/resources/META-INF/persistence.xml -->
    <property name="persistenceUnitName" value="myTestPersistenceUnit" />
    <property name="jpaVendorAdapter">
        <bean
            class="org.springframework.orm.jpa.vendor.HibernateJpaVendorAdapter">
        </bean>
    </property>
</bean>

Here, /src/test/resources/META-INF/persistence.xml (copied into target/test-classes) would be preferred over /src/main/resources/META-INF/persistence.xml (copied into target/classes).

Unfortunately, the location of the persistence.xml file also determines the so-called "persistence unit's root", which then determines which classes are scanned for @Entity annotations. So, using /src/test/resources/META-INF/persistence.xml would scan classes in target/test-classes, not classes in target/classes (where the classes that need to be tested would live).

Hence, for testing, one would need to explicitly add <class> entries to persistence.xml, to avoid java.lang.IllegalArgumentException: Not an entity: class .... The need for <class> entries can be avoided by using a different file name, like persistence-TEST.xml, and put that file in the very same folder as the regular persistence.xml file. The Spring context from your test folder can then just refer to <property name="persistenceXmlLocation" value="META-INF/persistence-TEST.xml" />, and Spring will find it for you in src/main.

As an alternative, one might be able to keep persistence.xml the same for the actual application and the tests, and only define one in src/main. Most configuration such as the drivers, dialect and optional credentials can be done in the Spring context instead. Also settings such as hibernate.hbm2ddl.auto can be passed in the context:

<bean id="dataSource"
    class="org.springframework.jdbc.datasource.DriverManagerDataSource">
    <!-- For example: com.mysql.jdbc.Driver or org.h2.Driver -->
    <property name="driverClassName" value="#{myConfig['db.driver']}" />
    <!-- For example: jdbc:mysql://localhost:3306/myDbName or 
        jdbc:h2:mem:test;DB_CLOSE_DELAY=-1 -->
    <property name="url" value="#{myConfig['db.url']}" />
    <!-- Ignored for H2 -->
    <property name="username" value="#{myConfig['db.username']}" />
    <property name="password" value="#{myConfig['db.password']}" />
</bean>

<bean id="jpaAdaptor"
    class="org.springframework.orm.jpa.vendor.HibernateJpaVendorAdapter">
    <!-- For example: org.hibernate.dialect.MySQL5Dialect or 
        org.hibernate.dialect.H2Dialect -->
    <property name="databasePlatform" value="#{myConfig['db.dialect']}" />
</bean>

<bean id="entityManagerFactory"
    class="org.springframework.orm.jpa.LocalContainerEntityManagerFactoryBean">
    <property name="dataSource" ref="dataSource" />
    <property name="jpaVendorAdapter" ref="jpaAdapter" />
    <property name="jpaProperties">
        <props>
            <!-- For example: validate, update, create or create-drop -->
            <prop key="hibernate.hbm2ddl.auto">#{myConfig['db.ddl']}</prop>
            <prop key="hibernate.show_sql">#{myConfig['db.showSql']}</prop>
            <prop key="hibernate.format_sql">true</prop>
        </props>
    </property>
</bean>

It seems multiple persistence.xml files is a general problem with JPA, solved only by classloading tricks.

A workaround that works for me is to define multiple persistence units in one persistence.xml file and then make sure that your deployment and test code use a different binding (in Spring you can set the "persistenceUnitName" property on the entity manager factory). It pollutes your deployment file with the test configuration, but if you don't mind that it works ok.

Add a persistance.xml for tests: /src/test/resources/META-INF/persistence.xml As @Arjan said, that would change persistance unit's root and entity classes would be scanned in target/test-classes. To handle that, add jar-file element to this persistance.xml:

/src/test/resources/META-INF/persistence.xml

<persistence xmlns="http://java.sun.com/xml/ns/persistence"
             xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
             xsi:schemaLocation="http://java.sun.com/xml/ns/persistence http://java.sun.com/xml/ns/persistence/persistence_2_0.xsd"
             version="2.0">
    <persistence-unit name="com.some.project">
        <provider>org.hibernate.jpa.HibernatePersistenceProvider</provider>
        <jar-file>${project.basedir}/target/classes</jar-file>
        <properties>
            <property name="javax.persistence.jdbc.url" value="jdbc:postgresql://localhost:5432/test_database" />
            <property name="javax.persistence.jdbc.driver" value="org.postgresql.Driver" />
            <property name="javax.persistence.jdbc.user" value="user" />
            <property name="javax.persistence.jdbc.password" value="..." />
        </properties>
    </persistence-unit>
</persistence>

Then, add filtering of test resources to your pom.xml:

<project>
    ...
    <build>
        ...
        <testResources>
            <testResource>
                <directory>src/test/resources</directory>
                <filtering>true</filtering>
            </testResource>
        </testResources>
        ...
    </build>
...
</project>

This will work because jar-file can target to directories, not only to jar files.

I prefer the solution of using different persistence.xml for testing and production as Rich Seller post (thanks!!).

But need to change:

<copy file="${project.build.outputDirectory}/META-INF/persistence.xml.proper" tofile="${project.build.outputDirectory}/META-INF/persistence.xml"/>

for:

<move file="${project.build.outputDirectory}/META-INF/persistence.xml.proper" tofile="${project.build.outputDirectory}/META-INF/persistence.xml" overwrite="true"/>

In order persistence.xml.proper not embedded in .jar file

How to configure JPA for testing in Maven

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