# This is file Test1.pm
package Test1;
# End of File

# This is file test2.pm
package Test2;
# End of File

# This is file Test3.pm
package Test;
# End of File

##</code><code>##

foreach my $name (qw(Test1 test2 Test3)) {
  unless(file_defines_package_of_same_name($name)) {
    print "$name\n";
  }
}

##</code><code>##

test2
Test3

##</code><code>##

# NOT TESTED!!!!
sub file_defines_package_of_same_name
{
  my $name=shift;
  eval {  
    require $name;
    { no strict; $name->import(); } # I guess I don't need this, do I?
    defined(eval 'scalar(keys(%'.$name.'::))');
  }
}