use Test::More tests => 2;

sub undef_hash
{
    my $ref = shift;
    undef $ref;
}

sub assign_hash
{
    my $ref = shift;
    %$ref   = ();
}

my $hash_one = { qw( foo bar baz quux ) };
undef_hash( $hash_one );
is( keys %$hash_one, 2,
    'undef on hash reference should not clear it' );

my $hash_two = { qw( foo bar baz quux ) };
assign_hash( $hash_two );
is( keys %$hash_two, 0,
    'assigning empty list to hash reference should clear it' );