Spring @Transactional - can one test the number of transactions?

Question

I have an api class annotated with @Transactional as shown. Some subset of the methods are further annotated with readOnly=true. When writing tests is there any way to verify the number of transactions that actually take place? Consider if the delete method implementation called the exist method - then in a test calling delete only one transaction should occur. However, if the test itself calls the exist method prior to calling delete then 2 transactions should take place.

@Transactional
public class AnApi {

    public AnEntity create(EntityData data) {...}

    public void delete(Long id) {...}

    @Transactional(readOnly = true)
    public boolean exists(Long id) {...}
}

While I know the framework functions this way, it is preferable to put in tests to detect any future changes and avoid potential surprises.

Answer 1

That shouldn't be too difficult.

Spring uses a PlatfromTransactionManager for managing transactions. If you register a wrapped transaction manager that implements this interface by delegating to the actual transaction manager, you should be easily able to count the invocations/number of transactions returned.