From 5cf56adce71ca27524289e70a8975de3aa4e14eb Mon Sep 17 00:00:00 2001
From: Benjamin Kampmann <ben@gnunicorn.org>
Date: Thu, 25 Nov 2021 15:46:17 +0100
Subject: [PATCH] Adding result-signature support for wasm32 async-test-macro

---
 crates/matrix-sdk-test-macros/Cargo.toml |  5 ++
 crates/matrix-sdk-test-macros/src/lib.rs | 64 ++++++++++++++++++++++--
 2 files changed, 65 insertions(+), 4 deletions(-)

diff --git a/crates/matrix-sdk-test-macros/Cargo.toml b/crates/matrix-sdk-test-macros/Cargo.toml
index c75820710..cc7c527ac 100644
--- a/crates/matrix-sdk-test-macros/Cargo.toml
+++ b/crates/matrix-sdk-test-macros/Cargo.toml
@@ -13,3 +13,8 @@ version = "0.1.0"
 
 [lib]
 proc-macro = true
+
+[dependencies]
+proc-macro2 = "1.0.29"
+quote = "1"
+syn = { version = "1.0.81", features = ["full",] }
\ No newline at end of file
diff --git a/crates/matrix-sdk-test-macros/src/lib.rs b/crates/matrix-sdk-test-macros/src/lib.rs
index c2be71d6e..72ce4ffd3 100644
--- a/crates/matrix-sdk-test-macros/src/lib.rs
+++ b/crates/matrix-sdk-test-macros/src/lib.rs
@@ -1,15 +1,71 @@
 use proc_macro::TokenStream;
+use quote::ToTokens;
+use syn::parse::{Parse, ParseBuffer};
+use syn::parse_macro_input;
+use quote::{quote, format_ident};
+use syn;
 
 /// Attribute to use `wasm_bindgen_test` for wasm32 targets and `tokio::test`
 /// for everything else
 #[proc_macro_attribute]
-pub fn async_test(_attr: TokenStream, item: TokenStream) -> TokenStream {
+pub fn async_test(_attr: TokenStream, item: TokenStream) -> TokenStream  {
+
+    let fun = parse_macro_input!(item as syn::ItemFn);
+    if fun.sig.output == syn::ReturnType::Default {
+        let attrs = r#"
+            #[cfg_attr(not(target_arch = "wasm32"), tokio::test)]
+            #[cfg_attr(target_arch = "wasm32", wasm_bindgen_test::wasm_bindgen_test)]
+        "#;
+
+        let mut out: TokenStream = attrs.parse().expect("Static works");
+        let inner : TokenStream = fun.into_token_stream().into();
+        out.extend(inner);
+        return out
+    }
+
     let attrs = r#"
-        #[cfg_attr(target_arch = "wasm32", wasm_bindgen_test)]
         #[cfg_attr(not(target_arch = "wasm32"), tokio::test)]
     "#;
 
-    let mut out: TokenStream = attrs.parse().unwrap();
-    out.extend(item);
+    let mut out: TokenStream = attrs.parse().expect("Static works.");
+
+    let mut outer = fun.clone();
+    let fn_name = fun.sig.ident.clone();
+    let fn_call : TokenStream = if fun.sig.asyncness.is_some() {
+        quote!{
+            {
+                assert!(#fn_name().await.is_ok());
+            }
+        }
+    } else {
+        quote!{
+            {
+                assert!(#fn_name().is_ok());
+            }
+        }
+    }.into();
+    outer.sig.output = syn::ReturnType::Default;
+    outer.sig.ident = format_ident!("{}_outer", fun.sig.ident);
+    outer.block = Box::new(parse_macro_input!(fn_call as syn::Block));
+
+
+    let inner : TokenStream = fun.into_token_stream().into();
+    out.extend(inner);
+
+    let attrs = r#"
+        #[cfg_attr(target_arch = "wasm32", wasm_bindgen_test::wasm_bindgen_test)]
+    "#;
+    let outer_attrs: TokenStream = attrs.parse().expect("Static works.");
+    let of : TokenStream = outer.into_token_stream().into();
+    out.extend(outer_attrs);
+    out.extend(of);
+
     out
 }
+
+// Attribute to use `wasm_bindgen_test` for wasm32 targets and `tokio::test`
+// for everything else
+// #[cfg(not(target_arch = "wasm32"))]
+// #[proc_macro_attribute]
+// pub fn async_test(_attr: TokenStream, item: TokenStream) -> TokenStream  {
+// }