fix: append #[::core::prelude::v1::test] only if it does not exist

Cargo.toml

@@ -70,3 +70,7 @@ tracing = {version = "0.1.20"}
 #
 # Probably fixed by https://github.com/rust-lang-nursery/lazy-static.rs/pull/107.
 _lazy_static_unused = { package = "lazy_static", version = "1.0.2" }
+
+[patch.crates-io]
+test-case = { git = "https://github.com/kezhuw/test-case.git", branch = "test-proc-macros-cooperation" }
+tokio = { git = "https://github.com/kezhuw/tokio.git", branch = "test-proc-macros-cooperation" }

macros/src/lib.rs

@@ -43,13 +43,28 @@ fn parse_attrs(attrs: Vec<Attribute>) -> syn::Result<(AttributeArgs, Vec<Attribu
   }
 }
 
-fn try_test(attr: TokenStream, input: ItemFn) -> syn::Result<Tokens> {
-  let inner_test = if attr.is_empty() {
-    quote! { ::core::prelude::v1::test }
-  } else {
-    attr.into()
+// Check whether given attribute is `#[test]` or `#[::core::prelude::v1::test]`.
+fn is_test_attribute(attr: &Attribute) -> bool {
+  let path = match &attr.meta {
+    syn::Meta::Path(path) => path,
+    _ => return false,
   };
+  let segments = ["core", "prelude", "v1", "test"];
+  if path.leading_colon.is_none() {
+    return path.segments.len() == 1
+      && path.segments[0].arguments.is_none()
+      && path.segments[0].ident == "test";
+  } else if path.segments.len() != segments.len() {
+    return false;
+  }
+  path
+    .segments
+    .iter()
+    .zip(segments)
+    .all(|(segment, path)| segment.arguments.is_none() && segment.ident == path)
+}
 
+fn try_test(attr: TokenStream, input: ItemFn) -> syn::Result<Tokens> {
   let ItemFn {
     attrs,
     vis,
@@ -61,9 +76,23 @@ fn try_test(attr: TokenStream, input: ItemFn) -> syn::Result<Tokens> {
   let logging_init = expand_logging_init(&attribute_args);
   let tracing_init = expand_tracing_init(&attribute_args);
 
+  let (inner_test, generated_test) = if attr.is_empty() {
+    let has_test = ignored_attrs.iter().any(is_test_attribute);
+    let generated_test = if has_test {
+      quote! {}
+    } else {
+      quote! { #[::core::prelude::v1::test]}
+    };
+    (quote! {}, generated_test)
+  } else {
+    let attr = Tokens::from(attr);
+    (quote! { #[#attr] }, quote! {})
+  };
+
   let result = quote! {
-    #[#inner_test]
+    #inner_test
     #(#ignored_attrs)*
+    #generated_test
     #vis #sig {
       // We put all initialization code into a separate module here in
       // order to prevent potential ambiguities that could result in

tests/mod.rs

@@ -57,6 +57,44 @@ fn with_inner_test_attribute_and_test_args_and_panic(x: i8, _y: i8) {
   assert_eq!(x, 0);
 }
 
+#[test_log::test]
+#[test]
+fn with_existing_test_attribute() {}
+
+#[test_log::test]
+#[::core::prelude::v1::test]
+fn with_existing_generated_test_attribute() {}
+
+#[tokio::test]
+#[test_log::test]
+async fn with_append_test_attribute_and_async() {
+  assert_eq!(async { 42 }.await, 42)
+}
+
+#[test_case::test_case(-2, -4)]
+#[test_case::test_case(-2, -5)]
+#[test_log::test]
+fn with_append_test_attribute_and_test_args(x: i8, _y: i8) {
+  assert_eq!(x, -2);
+}
+
+#[should_panic]
+#[test_case::test_case(-2, -4)]
+#[test_case::test_case(-3, -4)]
+#[test_log::test]
+fn with_append_test_attribute_and_test_args_and_panic(x: i8, _y: i8) {
+  assert_eq!(x, 0);
+}
+
+#[should_panic]
+#[test_case::test_case(-2, -4)]
+#[test_case::test_case(-3, -4)]
+#[tokio::test]
+#[test_log::test]
+async fn with_append_test_attribute_and_test_args_and_panic_async(x: i8, _y: i8) {
+  assert_eq!(x, 0);
+}
+
 #[instrument]
 async fn instrumented(input: usize) -> usize {
   info!("input = {}", input);