use Test::More 'tests' => 5;

ok( 'foo' =~ //,            'empty regex matches' );
ok( 'foo' =~ /foo/,         '/foo/ matches' );
ok( !('bar' =~ //),         'repeated match of foo' );
ok( !('bar' =~ /\Q/),       'repeated match with \\Q' );
my $empty = '';
ok( !('bar' =~ /\Q$empty/), 'interpolated empty string same as \\Q' );