use DBI;
{
  my $real_connect = DBI->can('connect');
  no warnings 'redefine';
  local *DBI::connect = sub {
    my($self, $ds, $user, $pass, $attr) = @_;
    $ds =~ s/yourdb/testdb/;
    $self->$real_connect($ds, $user, $pass, $attr);
  };

  my $exit = simulate_perl_program('yourprogram.plx', @args);
}