#[test]
fn test() -> Result<(), syn::Error> {
    let input = quote! {
        #[template(ext = "", source = "{{ z!{r#} }}")]
//                                           ^^ must be followed by a string literal
        enum q {}
    };
    let output = derive_template(input, import_askama);
    let _: syn::File = syn::parse2(output)?;
    Ok(())
}

z!(r#)