Using orientdb/blueprints, this test case shows that removing a vertex does not remove its reference in connected vertices.

DeleteVertexTest.java

import static org.junit.Assert.*;

import java.util.Iterator;

import org.junit.After;
import org.junit.Test;
import org.junit.runner.RunWith;
import org.junit.runners.JUnit4;

import com.orientechnologies.orient.core.type.tree.OMVRBTreeRIDSet;
import com.tinkerpop.blueprints.Direction;
import com.tinkerpop.blueprints.Edge;
import com.tinkerpop.blueprints.Vertex;
import com.tinkerpop.blueprints.impls.orient.OrientGraph;
import com.tinkerpop.blueprints.impls.orient.OrientVertex;

@RunWith(JUnit4.class)
public class DeleteVertexTest {

	@After
	public void tearDown() {
		OrientGraph g = createGraph();
		for (Iterator<Vertex> it = g.getVertices().iterator(); it.hasNext();) {
			it.next().remove();
		}
		g.shutdown();
	}

	@Test
	public void shouldDeleteEdgesWhenDeletingVertex() {

		// Create a node v1 with at least two edges
		OrientGraph g = createGraph();
		OrientVertex v1 = g.addVertex("class:V1");
		OrientVertex v2 = g.addVertex("class:V2");
		OrientVertex v22 = g.addVertex("class:V2");

		g.addEdge(null, v1, v2, "edgeType1");
		g.addEdge(null, v1, v22, "edgeType1");

		g.shutdown();

		// delete connected vertex v2
		g = createGraph();

		g.getVertex(v2.getId()).remove();

		// the v1 out_edgeType1 property should not contain a reference to
		// deleted node v2
		// OK INSIDE THE TRANSACTION
		OMVRBTreeRIDSet out_edge = g.getVertex(v1.getId()).getProperty(
				"out_edgeType1");
		assertFalse(out_edge.contains(v2.getId()));
		g.shutdown();

		// the v1 node should only have one edge left
		//OK
		assertEquals(1, getEdgeCount(v1.getId()));
		
		g = createGraph();
		//v2 vertex sould be deleted
		//OK
		assertNull(g.getVertex(v2.getId()));
		
		// the v1 out_edgeType1 property should not contain a reference to
		// deleted v2
		// FAILS HERE OUTSIDE OF THE TRANSACTION
		out_edge = g.getVertex(v1.getId()).getProperty("out_edgeType1");
		assertFalse(out_edge.contains(v2.getId()));
	}

	int getEdgeCount(Object vid) {
		OrientGraph g = createGraph();
		int n = 0;
		for (Iterator<Edge> it = g.getVertex(vid).getEdges(Direction.BOTH)
				.iterator(); it.hasNext(); n++) {
			it.next();
		}
		g.shutdown();
		return n;
	}

	private OrientGraph createGraph() {
		return new OrientGraph("memory:db");
	}

}