@Test
    public void shouldNotFindTheStepIndex() {
        final Traversal.Admin traversal = new DefaultTraversal<>(EmptyGraph.instance());
        final IdentityStep identityStep = new IdentityStep(traversal);
        traversal.asAdmin().addStep(0, new HasStep(traversal));
        traversal.asAdmin().addStep(0, new HasStep(traversal));
        traversal.asAdmin().addStep(0, new HasStep(traversal));

        assertEquals(-1, TraversalHelper.stepIndex(identityStep, traversal));
    }
@author Marko A. Rodriguez (http://markorodriguez.com)
@author Stephen Mallette (http://stephen.genoprime.com)
gremlin-core/src/test/java/org/apache/tinkerpop/gremlin/process/traversal/util/TraversalHelperTest.java