Add attribute crate to proc-macro wasm-bindgen-test (#3593)

Author: FirelightFlagboy

CHANGELOG.md

@@ -42,6 +42,10 @@
 * Add bindings for `CanvasTransform.setTransform(DOMMatrix2DInit)`.
   [#3580](https://github.com/rustwasm/wasm-bindgen/pull/3580)
 
+* Add a `crate` attribute to the `wasm_bindgen_test` proc-macro to specify a
+  non-default path to the `wasm-bindgen-test` crate.
+  [#3593](https://github.com/rustwasm/wasm-bindgen/pull/3593)
+
 ### Changed
 
 * Updated the WebGPU WebIDL.

crates/test-macro/Cargo.toml

@@ -14,6 +14,7 @@ proc-macro = true
 [dependencies]
 proc-macro2 = "1.0"
 quote = "1.0"
+syn = { version = "2.0", default-features = false, features = [ "parsing", "proc-macro", "derive", "printing" ] }
 
 [dev-dependencies]
 wasm-bindgen-test = { path = "../test" }

crates/test-macro/src/lib.rs

@@ -16,30 +16,11 @@ pub fn wasm_bindgen_test(
     attr: proc_macro::TokenStream,
     body: proc_macro::TokenStream,
 ) -> proc_macro::TokenStream {
-    let mut attr = attr.into_iter();
-    let mut r#async = false;
+    let mut attributes = Attributes::default();
+    let attribute_parser = syn::meta::parser(|meta| attributes.parse(meta));
+
+    syn::parse_macro_input!(attr with attribute_parser);
     let mut should_panic = None;
-    while let Some(token) = attr.next() {
-        match &token {
-            proc_macro::TokenTree::Ident(i) if i.to_string() == "async" => r#async = true,
-            _ => {
-                return compile_error(
-                    token.span().into(),
-                    "malformed `#[wasm_bindgen_test]` attribute",
-                )
-            }
-        }
-        match &attr.next() {
-            Some(proc_macro::TokenTree::Punct(op)) if op.as_char() == ',' => {}
-            Some(_) => {
-                return compile_error(
-                    token.span().into(),
-                    "malformed `#[wasm_bindgen_test]` attribute",
-                )
-            }
-            None => break,
-        }
-    }
 
     let mut body = TokenStream::from(body).into_iter().peekable();
 
@@ -64,7 +45,7 @@ pub fn wasm_bindgen_test(
         leading_tokens.push(token.clone());
         if let TokenTree::Ident(token) = token {
             if token == "async" {
-                r#async = true;
+                attributes.r#async = true;
             }
             if token == "fn" {
                 break;
@@ -83,7 +64,7 @@ pub fn wasm_bindgen_test(
         None => quote! { ::core::option::Option::None },
     };
 
-    let test_body = if r#async {
+    let test_body = if attributes.r#async {
         quote! { cx.execute_async(test_name, #ident, #should_panic); }
     } else {
         quote! { cx.execute_sync(test_name, #ident, #should_panic); }
@@ -93,10 +74,11 @@ pub fn wasm_bindgen_test(
     // later slurp up all of these functions and pass them as arguments to the
     // main test harness. This is the entry point for all tests.
     let name = format_ident!("__wbgt_{}_{}", ident, CNT.fetch_add(1, Ordering::SeqCst));
+    let wasm_bindgen_path = attributes.wasm_bindgen_path;
     tokens.extend(
         quote! {
             #[no_mangle]
-            pub extern "C" fn #name(cx: &::wasm_bindgen_test::__rt::Context) {
+            pub extern "C" fn #name(cx: &#wasm_bindgen_path::__rt::Context) {
                 let test_name = ::core::concat!(::core::module_path!(), "::", ::core::stringify!(#ident));
                 #test_body
             }
@@ -205,3 +187,30 @@ fn find_ident(iter: &mut impl Iterator<Item = TokenTree>) -> Option<Ident> {
 fn compile_error(span: Span, msg: &str) -> proc_macro::TokenStream {
     quote_spanned! { span => compile_error!(#msg); }.into()
 }
+
+struct Attributes {
+    r#async: bool,
+    wasm_bindgen_path: syn::Path,
+}
+
+impl Default for Attributes {
+    fn default() -> Self {
+        Self {
+            r#async: false,
+            wasm_bindgen_path: syn::parse_quote!(::wasm_bindgen_test),
+        }
+    }
+}
+
+impl Attributes {
+    fn parse(&mut self, meta: syn::meta::ParseNestedMeta) -> syn::parse::Result<()> {
+        if meta.path.is_ident("async") {
+            self.r#async = true;
+        } else if meta.path.is_ident("crate") {
+            self.wasm_bindgen_path = meta.value()?.parse::<syn::Path>()?;
+        } else {
+            return Err(meta.error("unknown attribute"));
+        }
+        Ok(())
+    }
+}

crates/test-macro/ui-tests/crate.rs

@@ -0,0 +1,20 @@
+#![no_implicit_prelude]
+
+extern crate wasm_bindgen_test_macro;
+//
+use wasm_bindgen_test_macro::wasm_bindgen_test;
+
+pub mod wasm {
+    pub extern crate wasm_bindgen_test as test;
+}
+
+#[wasm_bindgen_test(crate = ::wasm_bindgen_test)]
+fn success_1() {}
+
+#[wasm_bindgen_test(crate = crate::wasm::test)]
+fn success_2() {}
+
+#[wasm_bindgen_test(crate = foo)]
+fn failure_1() {}
+
+fn main() {}

crates/test-macro/ui-tests/crate.stderr

@@ -0,0 +1,5 @@
+error[E0433]: failed to resolve: use of undeclared crate or module `foo`
+  --> ui-tests/crate.rs:17:29
+   |
+17 | #[wasm_bindgen_test(crate = foo)]
+   |                             ^^^ use of undeclared crate or module `foo`