Just a note. While 100% coverage is a fine goal you may still have issues. Having a test does not make it a good test. My classic example (really happened) is:

sub is_integer { 
    return 0 unless defined $_[0];
    return $_[0] =~ m/^\d$/ ? 1 : 0 
}
[download]

The guy that wrote this snippet of code had 10 tests for it! He tested the numbers 0..9 and it passed every test...... It broke on demo with client 10 whose ID was not a valid integer according to that code.....

So the moral is that coverage is one aspect but testing the data range, edge cases, and totally invalid data is another.