Move /src/test to /tests

tests/ui/async-await/async-trait-fn.rs

@@ -0,0 +1,11 @@
+// edition:2018
+trait T {
+    async fn foo() {} //~ ERROR functions in traits cannot be declared `async`
+    async fn bar(&self) {} //~ ERROR functions in traits cannot be declared `async`
+    async fn baz() { //~ ERROR functions in traits cannot be declared `async`
+        // Nested item must not ICE.
+        fn a() {}
+    }
+}
+
+fn main() {}