Some process tests require the graph API

This test uses the graph API:
https://github.com/apache/tinkerpop/blob/master/gremlin-test/src/main/java/org/apache/tinkerpop/gremlin/process/traversal/step/map/AddEdgeTest.java#L137-L142

This test assumes that the reference to the vertex will be updated. It should at least fetch the vertex again after it has been updated, but ideally use a traversal for verification.
https://github.com/apache/tinkerpop/blob/master/gremlin-test/src/main/java/org/apache/tinkerpop/gremlin/process/traversal/strategy/decoration/PartitionStrategyProcessTest.java#L142-L143

These tests disable the strategies supplied by the implementing graph and therefore they will default to using the graph API under the hood.
https://github.com/apache/tinkerpop/blob/master/gremlin-test/src/main/java/org/apache/tinkerpop/gremlin/process/traversal/CoreTraversalTest.java#L222-L261