The current PHPC test suite depends on a number of standalone and replica set topologies deployed by mongo-orchestration running within a Vagrant box. There are a few issues with this:

• Each test, if it communicates with a server at all, uses only a single URI. This means that a generic query test likely only runs against the STANDALONE environment (latest MongoDB version) instead of multiple topologies.
• We have several tests that are quite fragile. Some depend on a second VM, which hosts an LDAP server. Others are cluster tests that attempt to create their own replica sets on the same mongo-orchestration instance to test failovers and the like.
• Outside of the cluster tests, we have no shard cluster test coverage.

Ideally, the PHPC test suite should function more like PHPLIB (and libmongoc), in that each test attempts to run on some generic URI environment variable. Tests can then decide if the topology is suitable and skip if not.