From aff83b31dc56ac3d14f648bf893470a062706364 Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Johel=20Ernesto=20Guerrero=20Pe=C3=B1a?=
 <johelegp@gmail.com>
Date: Sat, 5 Sep 2020 22:39:34 -0400
Subject: [PATCH] test: codify comment

---
 test/unit_test/static/unit_test.cpp | 3 +++
 1 file changed, 3 insertions(+)

diff --git a/test/unit_test/static/unit_test.cpp b/test/unit_test/static/unit_test.cpp
index 125db502..23ca50d6 100644
--- a/test/unit_test/static/unit_test.cpp
+++ b/test/unit_test/static/unit_test.cpp
@@ -40,6 +40,9 @@ struct hour : named_scaled_unit<hour, "h", no_prefix, ratio(36, 1, 2), second> {
 struct dim_time : base_dimension<"time", second> {};
 
 struct kelvin : named_unit<kelvin, "K", no_prefix> {};
+#if COMP_MSVC || COMP_GCC >= 10
+static_assert([]<Prefix R>() { return !requires { typename prefixed_unit<kelvin, R, kelvin>; }; }.template operator()<si::kilo>()); // negative unit ratio
+#endif
 // struct kilokelvin : prefixed_unit<kilokelvin, si::kilo, kelvin> {};  // should not compile (prefix not allowed for this reference unit)
 
 struct metre_per_second : unit<metre_per_second> {};