Refactored the server.get_result_datapoints() tests
Removed unnecessary the lines in server.aggregate_results_for_lvalue() doing padding of datapoints with too small a length. These lines proved to be unneccessary, as the existing code already takes such edge cases into account
Refactored the server.render() tests
Wrote tests for server.render() for cases where partial results are obtained from graphite; Handled the edge case where lvalue widgets have completely empty results.