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/*
 * lib.rs
 *
 * async-std-test - Alternate implementation of the async-std test macro
 * Copyright (c) 2022 Ammon Smith
 *
 * async-std-test is available free of charge under the terms of the MIT
 * License. You are free to redistribute and/or modify it under those
 * terms. It is distributed in the hopes that it will be useful, but
 * WITHOUT ANY WARRANTY. See the LICENSE file for more details.
 *
 */

#![forbid(unsafe_code, future_incompatible)]
#![deny(missing_debug_implementations, nonstandard_style)]

use proc_macro::TokenStream;
use quote::{quote, quote_spanned};
use syn::spanned::Spanned;

#[proc_macro_attribute]
pub fn async_test(_attr: TokenStream, item: TokenStream) -> TokenStream {
    let input = syn::parse_macro_input!(item as syn::ItemFn);

    let ret = &input.sig.output;
    let name = &input.sig.ident;
    let body = &input.block;
    let attrs = &input.attrs;
    let vis = &input.vis;

    if input.sig.asyncness.is_none() {
        return TokenStream::from(quote_spanned! { input.span() =>
            compile_error!("the async keyword is missing from the function declaration"),
        });
    }

    let result = quote! {
        #[::core::prelude::v1::test]
        #(#attrs)*
        #vis fn #name() #ret {
            async_std::task::block_on(async {
                let result = {
                    #body
                };

                if let Err(error) = result {
                    panic!("Error in test: {}", error);
                }
            })
        }
    };

    result.into()
}