In an Arquillian test class, any method marked @Deployment that returns something other than Archive is not being detected. For example, this method is not detected by the tooling, despite the fact that WebArchive extends Archive:

@Deployment
public static WebArchive createDeployment() {
...code to create deployment here...
}

As a result, the deployment validation features do not work, and the Arquillian Cruiser view does not allow the archive to be browsed. Curiously, however, there is no warning about a missing @Deployment method.