The problem is that these tests are asynchronous and thus need the `assertXXX` functions that `VertxAssert` provides. I wasn't aware of `assertThat` and there were some imports/hamcrest library missing. I'm adding that to the PR shortly.

Regarding the ScalaTest assertions: I doubt we can use them for the tests since they are not linked to the asynchronous test framework of Vert.x that `VertxAssert` provides.