From 43c7db49ff824577cff11cdd03d1f5bafcbd4b38 Mon Sep 17 00:00:00 2001
From: Felix Morgner <felix.morgner@gmail.com>
Date: Thu, 8 Jun 2023 08:16:53 +0200
Subject: tests: port hash tests

---
 source/lib/include/newtype/newtype.hpp |  4 +-
 source/tests/CMakeLists.txt            |  2 +-
 source/tests/src/hash.cpp              | 56 +++++++++++++++++++++++++++
 source/tests/src/hash_suite.cpp        | 69 ----------------------------------
 4 files changed, 59 insertions(+), 72 deletions(-)
 create mode 100644 source/tests/src/hash.cpp
 delete mode 100644 source/tests/src/hash_suite.cpp

diff --git a/source/lib/include/newtype/newtype.hpp b/source/lib/include/newtype/newtype.hpp
index e2704f3..2e71553 100644
--- a/source/lib/include/newtype/newtype.hpp
+++ b/source/lib/include/newtype/newtype.hpp
@@ -537,9 +537,9 @@ namespace std
   template<typename BaseType, typename TagType, auto DerivationClause>
   struct hash<nt::new_type<BaseType, TagType, DerivationClause>>
   {
-    template<typename BaseTypeT = BaseType, auto DerivationClauseV = DerivationClause>
+    template<typename BaseTypeT = BaseType>
     auto constexpr operator()(nt::new_type<BaseType, TagType, DerivationClause> const & object,
-                              std::enable_if_t<DerivationClauseV(nt::Hash) && nt::impl::is_hashable_v<BaseTypeT>> * = nullptr) const
+                              std::enable_if_t<DerivationClause(nt::Hash) && nt::impl::is_hashable_v<BaseTypeT>> * = nullptr) const
         -> std::size_t
     {
       return std::hash<BaseType>{}(object.decay());
diff --git a/source/tests/CMakeLists.txt b/source/tests/CMakeLists.txt
index f2c39e0..594b518 100644
--- a/source/tests/CMakeLists.txt
+++ b/source/tests/CMakeLists.txt
@@ -11,7 +11,7 @@ add_executable("${PROJECT_NAME}_tests"
   "src/conversion.cpp"
   "src/derivation_clause.cpp"
   # "src/equality_comparison_suite.cpp"
-  # "src/hash_suite.cpp"
+  "src/hash.cpp"
   # "src/io_operators_suite.cpp"
   # "src/iterable_suite.cpp"
   # "src/new_type_constructor_suite.cpp"
diff --git a/source/tests/src/hash.cpp b/source/tests/src/hash.cpp
new file mode 100644
index 0000000..173770a
--- /dev/null
+++ b/source/tests/src/hash.cpp
@@ -0,0 +1,56 @@
+#include "newtype/derivable.hpp"
+#include "newtype/deriving.hpp"
+#include "newtype/impl/type_traits_extensions.hpp"
+#include "newtype/newtype.hpp"
+
+#include <catch2/catch_test_macros.hpp>
+
+#include <unordered_map>
+
+SCENARIO("Hash", "[hash]")
+{
+  GIVEN("A new_type not deriving nt::Hash")
+  {
+    using type_alias = nt::new_type<int, struct tag>;
+
+    THEN("it is not hashable")
+    {
+      REQUIRE_FALSE(nt::impl::is_hashable_v<type_alias>);
+    }
+  }
+
+  GIVEN("A new_type over a hashable type deriving nt::Hash")
+  {
+    using type_alias = nt::new_type<int, struct tag, deriving(nt::Hash)>;
+
+    THEN("it is hashable")
+    {
+      REQUIRE(nt::impl::is_hashable_v<type_alias>);
+    }
+  }
+
+  GIVEN("A new_type over a non-hashable type deriving nt::Hash")
+  {
+    struct non_hashable
+    {
+    };
+    using type_alias = nt::new_type<non_hashable, struct tag, deriving(nt::Hash)>;
+
+    THEN("it is not hashable")
+    {
+      REQUIRE_FALSE(nt::impl::is_hashable_v<type_alias>);
+    }
+  }
+
+  GIVEN("A hashable new_type")
+  {
+    using type_alias = nt::new_type<int, struct tag, deriving(nt::Hash)>;
+
+    THEN("it can be used a the key in an unordered_map")
+    {
+      auto map = std::unordered_map<type_alias, int>{};
+      map[type_alias{42}] = 43;
+      REQUIRE(map[type_alias{42}] == 43);
+    }
+  }
+}
diff --git a/source/tests/src/hash_suite.cpp b/source/tests/src/hash_suite.cpp
deleted file mode 100644
index b482414..0000000
--- a/source/tests/src/hash_suite.cpp
+++ /dev/null
@@ -1,69 +0,0 @@
-#include "hash_suite.hpp"
-
-#include "kawaii.hpp"
-#include "newtype/derivable.hpp"
-#include "newtype/deriving.hpp"
-#include "newtype/impl/type_traits_extensions.hpp"
-#include "newtype/newtype.hpp"
-
-#include <cute/cute.h>
-
-#include <unordered_map>
-
-inline namespace hashable_tests
-{
-
-  auto a_new__type_that_does_not_include_hash_in_its_derivation_clause_is_not_hashable() -> void
-  {
-    using type_alias = nt::new_type<int, struct tag>;
-    ASSERT(!nt::impl::is_hashable_v<type_alias>);
-  }
-
-  auto a_new__type_that_does_include_hash_in_its_derivation_clause_is_hashable() -> void
-  {
-    static_assert(nt::impl::is_hashable_v<int>, "Sanity Check");
-    using type_alias = nt::new_type<int, struct tag, deriving(nt::Hash)>;
-    ASSERT(nt::impl::is_hashable_v<type_alias>);
-  }
-
-  auto a_new__type_that_does_include_hash_in_its_derivation_clause_but_whose_base_type_is_not_hashable_is_also_not_hashable() -> void
-  {
-    struct not_hashable
-    {
-    };
-
-    static_assert(!nt::impl::is_hashable_v<not_hashable>, "Sanity Check");
-    using type_alias = nt::new_type<not_hashable, struct tag, deriving(nt::Hash)>;
-    ASSERT(!nt::impl::is_hashable_v<type_alias>);
-  }
-
-}  // namespace hashable_tests
-
-inline namespace usage_tests
-{
-
-  auto a_new__type_that_is_hashable_can_be_used_in_an_unordered__map() -> void
-  {
-    static_assert(nt::impl::is_hashable_v<int>, "Sanity Check");
-    using type_alias = nt::new_type<int, struct tag, deriving(nt::Hash)>;
-
-    auto map = std::unordered_map<type_alias, int>{};
-    map[type_alias{42}] = 43;
-    ASSERT_EQUAL(43, map[type_alias{42}]);
-  }
-
-}  // namespace usage_tests
-
-auto hash_suite() -> std::pair<cute::suite, std::string>
-{
-  return {{
-              // Hashable Tests
-              KAWAII(a_new__type_that_does_not_include_hash_in_its_derivation_clause_is_not_hashable),
-              KAWAII(a_new__type_that_does_include_hash_in_its_derivation_clause_is_hashable),
-              KAWAII(a_new__type_that_does_include_hash_in_its_derivation_clause_but_whose_base_type_is_not_hashable_is_also_not_hashable),
-
-              // Usage Tests
-              KAWAII(a_new__type_that_is_hashable_can_be_used_in_an_unordered__map),
-          },
-          "std::hash Support Tests"};
-}
\ No newline at end of file
-- 
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