Is a Perl method defined?

Shell Programming and Scripting
1

In my code, I know I can write...

if ( defined &test_sub ) {
    test_sub();
} else {
    print "Subroutine doesn't exist";
}

This tests the existence of the test_sub subroutine without actually calling it.
If, though, I replace test_sub with a package method...

if ( defined &$TEST->test_sub ) {
    TEST->test_sub;
} else {
    print "Method doesn't exist";
}

I get

Not a CODE reference at (eval 22)[/opt/perl/5.8.0/lib/perl5db.pl:17] line 2, <STDIN> line 3.

Any suggestions what I'm doing wrong?

2 
my $method = 'Some::Sub';
if (defined(&$method)) {
    print("ok\n");
} else {
    print("oops\n");
}

Does that work for you?