From 58106618ac04fd84ae8b37fb145be13213f0c75b Mon Sep 17 00:00:00 2001
From: Mateusz Pusz <mateusz.pusz@gmail.com>
Date: Wed, 18 Sep 2019 18:34:54 -0600
Subject: [PATCH] ratio_pow and ratio_sqrt fixed + unit tests added

---
 src/include/units/ratio.h                     | 19 +++++++++++++++++--
 test/unit_test/CMakeLists.txt                 |  2 +-
 .../{test_tools.cpp => test_ratio.cpp}        | 15 +++++++++++++++
 3 files changed, 33 insertions(+), 3 deletions(-)
 rename test/unit_test/{test_tools.cpp => test_ratio.cpp} (72%)

diff --git a/src/include/units/ratio.h b/src/include/units/ratio.h
index 8a8a0a7f..09055d96 100644
--- a/src/include/units/ratio.h
+++ b/src/include/units/ratio.h
@@ -128,10 +128,15 @@ namespace std::experimental::units {
     };
 
     template<typename R>
-    struct ratio_pow_impl<R, 0> {
+    struct ratio_pow_impl<R, 1> {
       using type = R;
     };
 
+    template<typename R>
+    struct ratio_pow_impl<R, 0> {
+      using type = ratio<1>;
+    };
+
   }
 
   template<Ratio R, std::size_t N>
@@ -158,10 +163,20 @@ namespace std::experimental::units {
       return sqrt_impl(v, 1, v);
     }
 
+    template<typename R>
+    struct ratio_sqrt_impl {
+      using type = ratio<detail::sqrt_impl(R::num), detail::sqrt_impl(R::den)>;
+    };
+
+    template<std::intmax_t Den>
+    struct ratio_sqrt_impl<ratio<0, Den>> {
+      using type = ratio<0>;
+    };
+
   }
 
   template<Ratio R>
-  using ratio_sqrt = ratio<detail::sqrt_impl(R::den), detail::sqrt_impl(R::num)>;
+  using ratio_sqrt = detail::ratio_sqrt_impl<R>::type;
 
 
   // common_ratio
diff --git a/test/unit_test/CMakeLists.txt b/test/unit_test/CMakeLists.txt
index cbb5f987..328cbe37 100644
--- a/test/unit_test/CMakeLists.txt
+++ b/test/unit_test/CMakeLists.txt
@@ -25,7 +25,7 @@ add_library(unit_tests
     test_custom_units.cpp
     test_dimension.cpp
     test_quantity.cpp
-    test_tools.cpp
+    test_ratio.cpp
     test_type_list.cpp
     test_units.cpp
 )
diff --git a/test/unit_test/test_tools.cpp b/test/unit_test/test_ratio.cpp
similarity index 72%
rename from test/unit_test/test_tools.cpp
rename to test/unit_test/test_ratio.cpp
index 23899293..d60acfdf 100644
--- a/test/unit_test/test_tools.cpp
+++ b/test/unit_test/test_ratio.cpp
@@ -41,6 +41,21 @@ namespace {
   static_assert(std::is_same_v<ratio_divide<ratio<1, 8>, ratio<2>>, ratio<1, 16>>);
   static_assert(std::is_same_v<ratio_divide<ratio<6>, ratio<3>>, ratio<2>>);
 
+  static_assert(std::is_same_v<ratio_pow<ratio<2>, 0>, ratio<1>>);
+  static_assert(std::is_same_v<ratio_pow<ratio<2>, 1>, ratio<2>>);
+  static_assert(std::is_same_v<ratio_pow<ratio<2>, 2>, ratio<4>>);
+  static_assert(std::is_same_v<ratio_pow<ratio<2>, 3>, ratio<8>>);
+  static_assert(std::is_same_v<ratio_pow<ratio<1, 2>, 0>, ratio<1>>);
+  static_assert(std::is_same_v<ratio_pow<ratio<1, 2>, 1>, ratio<1, 2>>);
+  static_assert(std::is_same_v<ratio_pow<ratio<1, 2>, 2>, ratio<1, 4>>);
+  static_assert(std::is_same_v<ratio_pow<ratio<1, 2>, 3>, ratio<1, 8>>);
+
+  static_assert(std::is_same_v<ratio_sqrt<ratio<9>>, ratio<3>>);
+  static_assert(std::is_same_v<ratio_sqrt<ratio<4>>, ratio<2>>);
+  static_assert(std::is_same_v<ratio_sqrt<ratio<1>>, ratio<1>>);
+  static_assert(std::is_same_v<ratio_sqrt<ratio<0>>, ratio<0>>);
+  static_assert(std::is_same_v<ratio_sqrt<ratio<1, 4>>, ratio<1, 2>>);
+
   // common_ratio
 
   static_assert(std::is_same_v<common_ratio<ratio<1>, ratio<1000>>, ratio<1>>);