Improve message about butterfly tests with --features=deadlock_detection
It's confusing when trying to run the tests from the worksace root
@@ -218,7 +218,10 @@ impl SwimNet {
pub fn health_of(&self, from_entry: usize, to_entry: usize) -> Option<Health> {
assert!(cfg!(feature = "deadlock_detection"),
- "This test should be run with --features=deadlock_detection");
+ "This test should be run with --features=deadlock_detection. \
+ Make sure to execute `cargo test` in the butterfly crate subdirectory since \
+ features cannot be propagated through a virtual manifest \
+ (See https://github.com/rust-lang/cargo/issues/4942).");
let from = self.members
.get(from_entry)
