adds tests for edge cases
adds tests for edge cases

BrandwatchLtd/daterangepicker,ingdir/daterangepicker,ingdir/daterangepicker,BrandwatchLtd/daterangepicker,grahamscott/daterangepicker,ingdir/daterangepicker,grahamscott/daterangepicker,BrandwatchLtd/daterangepicker,grahamscott/daterangepicker