my $csv2 = Text::xSV->new( filename => 'filename.txt', ... );
my $new_filename = "popularixCombined.csv";
eval { $csv2->set_filename($new_filename) };
is( $@, undef, "Changing the filename does not raise an error");
is( $csv->get_filename, $new_filename, "... and sets the new filename" );