The arquillian glassfish embedded container (in the newest version 1.0.0.CR4) does simply ignore @Convert annotations (JPA 2.1) which leads to errors when running tests that use the persistence layer.
The error output contains
Internal Exception: Exception [EclipseLink-7155] (Eclipse Persistence Services - 2.2.0.v20110202-r8913)
which would explain, why it does not work. JPA 2.1 features are not implemented in EclipseLink 2.2.0. Why does arquillian-glassfish-embedded use such an outdated version of the persistence service?