public function testReplaceLiteralTriples()
{
$graph = new ExtendedGraph();
$graph->add_literal_triple("http://test/1", 'http://www.w3.org/2000/01/rdf-schema#label', "value1");
$graph->add_literal_triple("http://test/1", 'http://www.w3.org/2000/01/rdf-schema#label', "value2");
$graph->replace_literal_triples("http://test/1", 'http://www.w3.org/2000/01/rdf-schema#label', "value3");
$this->assertTrue($graph->has_literal_triple("http://test/1", 'http://www.w3.org/2000/01/rdf-schema#label', "value3"));
$this->assertFalse($graph->has_literal_triple("http://test/1", 'http://www.w3.org/2000/01/rdf-schema#label', "value1"));
$this->assertFalse($graph->has_literal_triple("http://test/1", 'http://www.w3.org/2000/01/rdf-schema#label', "value2"));
}