fix test macro in presence of other imports named test (#399)

actix-rt/tests/test-macro-import-conflict.rs

@@ -0,0 +1,17 @@
+//! Checks that test macro does not cause problems in the presence of imports named "test" that
+//! could be either a module with test items or the "test with runtime" macro itself.
+//!
+//! Before actix/actix-net#399 was implemented, this macro was running twice. The first run output
+//! `#[test]` and it got run again and since it was in scope.
+//!
+//! Prevented by using the fully-qualified test marker (`#[::core::prelude::v1::test]`).
+
+#![cfg(feature = "macros")]
+
+use actix_rt::time as test;
+
+#[actix_rt::test]
+async fn test_naming_conflict() {
+    use test as time;
+    time::sleep(std::time::Duration::from_millis(2)).await;
+}