Move /src/test to /tests

tests/ui/lint/dead-code/unused-enum.rs

@@ -0,0 +1,12 @@
+#![deny(unused)]
+
+struct F; //~ ERROR struct `F` is never constructed
+struct B; //~ ERROR struct `B` is never constructed
+
+enum E {
+    //~^ ERROR enum `E` is never used
+    Foo(F),
+    Bar(B),
+}
+
+fn main() {}