public function testSelectEmptyJson()
 {
     $result = new EasyRdf_Sparql_Result(readFixture('sparql_select_empty.json'), 'application/sparql-results+json');
     $this->assertSame(3, $result->numFields());
     $this->assertSame(array('s', 'p', 'o'), $result->getFields());
     $this->assertCount(0, $result);
 }