[hibernate-dev] Making tests nicer with lambdas

[Hardy Ferentschik]

On 25 Jan 2014, at 10:41, Gunnar Morling <gunnar at hibernate.org> wrote:

> I've played around a bit with the idea of using Java 8 lambdas to make
> tests easier to write and read. We have many tests which open a session and
> TX, do some stuff, commit, open a new TX (and/or session), do some
> assertions and so on:
> 
>    Session session = openSession();
>  Transaction transaction = session.beginTransaction();
> 
>    // heavy testing action...
>    transaction.commit();
>  session.clear();
> 
>    transaction = session.beginTransaction();
> 
>    // load, assert...
>  transaction.commit();
>  session.clear();
> 
> The same could look like this using Java 8 lambdas:
> 
>    Foo foo = inTransactionWithResult( (session, tx) -> {
>        // heavy testing action...
>  } );
> 
>    inTransaction( (session, tx) -> {
>        // load, assert...
>  } );
> 
> Extracting the session/TX handling removes quite some clutter and focuses
> more on the actual testing logic.

Makes things a but nicer. A bit of syntactic sugger. Not sure though whether it is enough to
switch to JDK 8 for building.

> It also avoids problems due to dangling
> transactions e.g. in case of assertion failures as the TX handling is done
> in a finally block in inTransaction().

A lot of this should already be taken care of by the CustomRunner we use to execute the tests.

—Hardy