rust-lang
diff --git a/‎library/core/tests/num/nan.rs
+8 b/‎library/core/tests/num/nan.rs
+8
diff --git a/‎src/test/ui/format-nan.rs
-9 b/‎src/test/ui/format-nan.rs
-9
@@ -0,0 +1,8 @@
+#[test]
+fn test_nan() {
+  use core::f64;
+  let x = "NaN".to_string();
+  assert_eq!(format!("{}", f64::NAN), x);
+  assert_eq!(format!("{:e}", f64::NAN), x);
+  assert_eq!(format!("{:E}", f64::NAN), x);
+}