    @Test
    public void testConcreteSP() {

        Extension extension = new Extension(new SingletonSet(),
                new ExtensionElem(new ValueConstant(FOAF.PERSON), "x"),
                new ExtensionElem(new ValueConstant(RDF.TYPE), "y"),
                new ExtensionElem(new ValueConstant(OWL.CLASS), "z"));
        Projection projection = new Projection(extension, new ProjectionElemList(
                new ProjectionElem("x", "subject"),
                new ProjectionElem("y", "predicate"),
                new ProjectionElem("z", "object")));
        ConstructConsequentVisitor visitor = new ConstructConsequentVisitor();
        projection.visit(visitor);
        Set<StatementPattern> expected = Sets.newHashSet(
                new StatementPattern(s(FOAF.PERSON), p(RDF.TYPE), o(OWL.CLASS)));
        Assert.assertEquals(expected, visitor.getConsequents());
    }