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

This way if preceding test macros add `#[::core::prelude::v1::test]` by
appending, then we can avoid duplicated test runs.

See also frondeus/test-case#101, frondeus/test-case#143

Closes d-e-s-o#35.

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

@@ -10,6 +10,7 @@ use quote::quote;
 
 use syn::parse::Parse;
 use syn::parse_macro_input;
+use syn::parse_quote;
 use syn::Attribute;
 use syn::Expr;
 use syn::ItemFn;
@@ -44,12 +45,6 @@ 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()
-  };
-
   let ItemFn {
     attrs,
     vis,
@@ -61,9 +56,24 @@ 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 test_attr: syn::Attribute = parse_quote! { #[::core::prelude::v1::test] };
+    let has_test = ignored_attrs.iter().any(|attr| *attr == test_attr);
+    let generated_test = if has_test {
+      quote! {}
+    } else {
+      quote! { #test_attr }
+    };
+    (quote! {}, generated_test)
+  } else {
+    let attr: Tokens = attr.into();
+    (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 +57,36 @@ fn with_inner_test_attribute_and_test_args_and_panic(x: i8, _y: i8) {
   assert_eq!(x, 0);
 }
 
+#[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);