remove a warning about unused macro

this the macro in serde_json is used only in test, remove it for non test. solution found [here)(rust-lang/rust#44342 (comment))
benashford · Oct 22, 2018 · 99acbc5 · 99acbc5
1 parent 7674b29
commit 99acbc5
Showing 1 changed file with 1 addition and 1 deletion.
diff --git a/src/lib.rs b/src/lib.rs
@@ -30,7 +30,7 @@ extern crate serde_derive;
 
 extern crate serde;
 
-#[macro_use]
+#[cfg_attr(test, macro_use)]
 extern crate serde_json;
 
 #[macro_use]