@Test
    public void shouldAddStepsCorrectly() {
        Traversal.Admin traversal = new DefaultTraversal<>(EmptyGraph.instance());
        traversal.asAdmin().addStep(0, new LambdaFilterStep(traversal, traverser -> true));
        traversal.asAdmin().addStep(0, new HasStep(traversal));
        traversal.asAdmin().addStep(0, new IdentityStep(traversal));
        validateToyTraversal(traversal);

        traversal = new DefaultTraversal<>(EmptyGraph.instance());
        traversal.asAdmin().addStep(0, new IdentityStep(traversal));
        traversal.asAdmin().addStep(1, new HasStep(traversal));
        traversal.asAdmin().addStep(2, new LambdaFilterStep(traversal, traverser -> true));
        validateToyTraversal(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