feat(test): add fallback test crate for no-metadata buildsHEADmain

Add `might_be_async_test_fallback` crate in `test/no_metadata/` to
verify macro behavior when the `metadata_async` feature is absent,
covering sync/async select, invoke, and bare func attributes

6 files changed, 81 insertions, 3 deletions

diff --git a/Makefile b/Makefile
index 20ea224..bf5bbda 100644
--- a/Makefile
+++ b/Makefile
@@ -1,7 +1,7 @@
-.PHONY: check clippy check-lock test-crate test-sync test-async expand fmt-expand lock doc
+.PHONY: check clippy check-lock test-crate test-sync test-async test-no-metadata expand fmt-expand lock doc
 
 # make check
-check: clippy expand fmt-expand test-crate test-sync test-async check-lock
+check: clippy expand fmt-expand test-crate test-sync test-async test-no-metadata check-lock
 
 # make doc
 doc:
@@ -27,6 +27,9 @@ test-sync:
 test-async:
 	cargo test -p might_be_async_test_async --features metadata_async --manifest-path test/Cargo.toml
 
+test-no-metadata:
+	cargo test -p might_be_async_test_fallback --features async --manifest-path test/Cargo.toml
+
 expand:
 	python3 scripts/expand_codes.py
 
diff --git a/test/Cargo.lock b/test/Cargo.lock
index 5d4be76..2e65476 100644
--- a/test/Cargo.lock
+++ b/test/Cargo.lock
@@ -137,6 +137,14 @@ dependencies = [
 ]
 
 [[package]]
+name = "might_be_async_test_fallback"
+version = "0.1.0"
+dependencies = [
+ "futures",
+ "might_be_async",
+]
+
+[[package]]
 name = "might_be_async_test_sync"
 version = "0.1.0"
 dependencies = [
diff --git a/test/Cargo.toml b/test/Cargo.toml
index b92b54b..68a4698 100644
--- a/test/Cargo.toml
+++ b/test/Cargo.toml
@@ -1,3 +1,3 @@
 [workspace]
-members = ["sync", "async"]
+members = ["sync", "async", "no_metadata"]
 resolver = "2"
diff --git a/test/no_metadata/Cargo.toml b/test/no_metadata/Cargo.toml
new file mode 100644
index 0000000..e228ecb
--- /dev/null
+++ b/test/no_metadata/Cargo.toml
@@ -0,0 +1,11 @@
+[package]
+name = "might_be_async_test_fallback"
+version = "0.1.0"
+edition = "2024"
+
+[features]
+async = []
+
+[dependencies]
+might_be_async = { path = "../.." }
+futures = "0.3"
diff --git a/test/no_metadata/src/lib.rs b/test/no_metadata/src/lib.rs
new file mode 100644
index 0000000..abe379d
--- /dev/null
+++ b/test/no_metadata/src/lib.rs
@@ -0,0 +1,2 @@
+#![allow(unused)]
+include!("../../src/test_fallback.rs");
diff --git a/test/src/test_fallback.rs b/test/src/test_fallback.rs
new file mode 100644
index 0000000..1f729fb
--- /dev/null
+++ b/test/src/test_fallback.rs
@@ -0,0 +1,54 @@
+#[might_be_async::func]
+fn fallback_id(x: i32) -> i32 {
+    x
+}
+
+#[cfg(not(feature = "async"))]
+#[test]
+fn test_fallback_func_sync() {
+    assert_eq!(fallback_id(42), 42);
+}
+
+#[cfg(feature = "async")]
+#[test]
+fn test_fallback_func_async() {
+    let r = futures::executor::block_on(fallback_id(42));
+    assert_eq!(r, 42);
+}
+
+#[cfg(not(feature = "async"))]
+#[test]
+fn test_fallback_select_implicit_sync() {
+    let r = might_be_async::select! { { 1 } else { 2 } };
+    assert_eq!(r, 2);
+}
+
+#[cfg(feature = "async")]
+#[test]
+fn test_fallback_select_implicit_async() {
+    let r = might_be_async::select! { { 1 } else { 2 } };
+    assert_eq!(r, 1);
+}
+
+#[cfg(not(feature = "async"))]
+fn fallback_double(x: i32) -> i32 {
+    x * 2
+}
+
+#[cfg(feature = "async")]
+async fn fallback_double(x: i32) -> i32 {
+    x * 2
+}
+
+#[cfg(not(feature = "async"))]
+#[test]
+fn test_fallback_invoke_sync() {
+    assert_eq!(might_be_async::invoke!(fallback_double(5)), 10);
+}
+
+#[cfg(feature = "async")]
+#[test]
+fn test_fallback_invoke_async() {
+    let r = futures::executor::block_on(async { might_be_async::invoke!(fallback_double(5)) });
+    assert_eq!(r, 10);
+}