{
    my $warning;
    local $SIG{__WARN__} = sub { $warning = shift };

    is( $warning, undef, 'no warnings recorded' );
    code_that_warns();
    is( $warning, 'expected warning',
        'code_that_warns() does indeed warn' );

    $warning = undef;
    non_warning_code();
    is( $warning, undef, 'non_warning_code() is clean' );
}