Integration tests failing in Grails & App Engine - google-app-engine

Question

I am using Grails with the App Engine plugin and JPA persistence. When running
grails test-app
my unit tests run perfectly, but I receive the error below when the integration tests start.
Is this a known issue with the app-engine plugin?
Starting integration tests ...
[copy] Copying 1 file to /home/matthew/.grails/1.1.1/projects/test-gae-jpa
[copy] Copying 1 file to /home/matthew/.grails/1.1.1/projects/test-gae-jpa
Error executing script TestApp: null
java.lang.ExceptionInInitializerError
at java.lang.Class.forName0(Native Method)
at java.lang.Class.forName(Class.java:169)
at AppEngineGrailsPlugin$_closure1.class$(AppEngineGrailsPlugin.groovy)
at AppEngineGrailsPlugin$_closure1.$get$$class$org$grails$appengine$AppEngineEntityManagerFactory(AppEngineGrailsPlugin.groovy)
at AppEngineGrailsPlugin$_closure1.doCall(AppEngineGrailsPlugin.groovy:70)
at AppEngineGrailsPlugin$_closure1.doCall(AppEngineGrailsPlugin.groovy)
at grails.spring.BeanBuilder.invokeBeanDefiningClosure(BeanBuilder.java:651)
at grails.spring.BeanBuilder.beans(BeanBuilder.java:501)
at grails.spring.BeanBuilder.invokeMethod(BeanBuilder.java:447)
at _GrailsBootstrap_groovy$_run_closure2_closure13.doCall(_GrailsBootstrap_groovy:86)
at _GrailsBootstrap_groovy$_run_closure2_closure13.doCall(_GrailsBootstrap_groovy)
at _GrailsSettings_groovy$_run_closure10.doCall(_GrailsSettings_groovy:274)
at _GrailsSettings_groovy$_run_closure10.call(_GrailsSettings_groovy)
at _GrailsBootstrap_groovy$_run_closure2.doCall(_GrailsBootstrap_groovy:84)
at _GrailsBootstrap_groovy$_run_closure7.doCall(_GrailsBootstrap_groovy:142)
at _GrailsTest_groovy$_run_closure7.doCall(_GrailsTest_groovy:249)
at _GrailsTest_groovy$_run_closure7.doCall(_GrailsTest_groovy)
at _GrailsTest_groovy$_run_closure1_closure19.doCall(_GrailsTest_groovy:110)
at _GrailsTest_groovy$_run_closure1.doCall(_GrailsTest_groovy:96)
at TestApp$_run_closure1.doCall(TestApp.groovy:66)
at gant.Gant$_dispatch_closure4.doCall(Gant.groovy:324)
at gant.Gant$_dispatch_closure6.doCall(Gant.groovy:334)
at gant.Gant$_dispatch_closure6.doCall(Gant.groovy)
at gant.Gant.withBuildListeners(Gant.groovy:344)
at gant.Gant.this$2$withBuildListeners(Gant.groovy)
at gant.Gant$this$2$withBuildListeners.callCurrent(Unknown Source)
at gant.Gant.dispatch(Gant.groovy:334)
at gant.Gant.this$2$dispatch(Gant.groovy)
at gant.Gant.invokeMethod(Gant.groovy)
at gant.Gant.processTargets(Gant.groovy:495)
at gant.Gant.processTargets(Gant.groovy:480)
at com.intellij.rt.execution.application.AppMain.main(AppMain.java:90)
Caused by: java.lang.NullPointerException
at org.datanucleus.jpa.EntityManagerFactoryImpl.initialisePMF(EntityManagerFactoryImpl.java:452)
at org.datanucleus.jpa.EntityManagerFactoryImpl.<init>(EntityManagerFactoryImpl.java:355)
at org.datanucleus.store.appengine.jpa.DatastoreEntityManagerFactory.<init>(DatastoreEntityManagerFactory.java:63)
at org.datanucleus.store.appengine.jpa.DatastorePersistenceProvider.createEntityManagerFactory(DatastorePersistenceProvider.java:35)
at javax.persistence.Persistence.createEntityManagerFactory(Persistence.java:51)
at javax.persistence.Persistence.createEntityManagerFactory(Persistence.java:33)
at javax.persistence.Persistence$createEntityManagerFactory.call(Unknown Source)
at org.grails.appengine.AppEngineEntityManagerFactory.<clinit>(AppEngineEntityManagerFactory.groovy:13)
... 32 more
Process finished with exit code 1