create @use specific tests

tests/use.rs

@@ -0,0 +1,12 @@
+#![cfg(test)]
+
+#[macro_use]
+mod macros;
+
+error!(
+    after_style,
+    "a {}
+    @use \"foo\";
+    ",
+    "Error: @use rules must be written before any other rules."
+);