you indeed need to remove it to be able to install the deps without providing an actual implementation. on travis we remove it: https://github.com/jackalope/jackalope/blob/master/.travis.yml#L11

but users need to be forced to install an actual implementation, not just the base library.

i usually run the tests inside jackalope-jackrabbit or jackalope-doctrine-dbal with `phpunit vendor/jackalope/jackalope/tests/` (which has the added benefit that i can run the phpcr-api-tests suite over the change immediately by calling just `phpunit` - the default phpunit.xml.dist even includes the tests of jackalope/jackalope.)