This may qualify as bug but am raising it as question for now.

After upgrade to Hibernate 1.5 (which happened automatically with the upgrade of spring-boot to 1.4.1.RELEASE) a few of test cases for my application, that uses hibernate (from spring-boot) with H2 (for testing), are failing.

The failed test cases are particularly the ones which should fail for unique key constraint when duplicate key is attempted to be inserted.

The application functions normally in runtime with MySql but the test cases doing the same functionality check fails. The tests have always passed with previously used Hibernate V4.3.11.FINAL (provided by spring-boot version 1.3.6)

FYI :
1. I attempted switching the testing DB to HSQL and those tests still fail.
2. The test cases pass as soon I downgrade the Hibernate to use 4.3.11 - <hibernate.version>4.3.11.Final</hibernate.version>

Can it be an issue with hibernate 5.0 to work with an embedded database or something else?

You should open a Jira issue along with a replicating test case. Try using the latest Hibernate version and see if the problem replicates there. Maybe it was an issue that got fixed.

Thanks for the pointer. Could you please also share the Jira url for the project? or should it be a Github issue?

Sure. This is the link:

https://hibernate.atlassian.net/projects/HHH