### Question:
RdfValueFactory implements ValueFactory { public RdfRepresentation createRdfRepresentation(IRI node, Graph graph) { if (node == null) { throw new IllegalArgumentException("The parsed id MUST NOT be NULL!"); } if(graph == null){ throw new IllegalArgumentException("The parsed graph MUST NOT be NULL!"); } return new RdfRepresentation(node, graph); } private  RdfValueFactory();  RdfValueFactory(Graph graph); static RdfValueFactory getInstance(); @Override RdfReference createReference(Object value); @Override RdfText createText(Object value); @Override RdfText createText(String text, String language); @Override RdfRepresentation createRepresentation(String id); RdfRepresentation createRdfRepresentation(IRI node, Graph graph); RdfRepresentation toRdfRepresentation(Representation representation);  }### Answer:
@Test(expected=IllegalArgumentException.class) public void testNullNodeRepresentation() { Graph graph = new IndexedGraph(); valueFactory.createRdfRepresentation(null, graph); }
@Test(expected=IllegalArgumentException.class) public void testNullGraphRepresentation() { IRI rootNode = new IRI("urn:test.rootNode"); valueFactory.createRdfRepresentation(rootNode, null); }