Add more hashmap test

Author: Julian LALU

interface/core/containers/hashmap.h

@@ -12,7 +12,9 @@ namespace hud
             using key_type = key_t;
             using value_type = value_t;
 
-            constexpr explicit slot(const key_type &key, const value_type &value) noexcept
+            template<typename u_key_t, typename u_value_t>
+            requires(hud::is_constructible_v<hud::pair<key_type, value_type>, u_key_t, u_value_t>)
+            constexpr explicit slot(const u_key_t &key, const u_value_t &value) noexcept
                 : element_(key, value)
             {
             }
@@ -24,6 +26,21 @@ namespace hud
             {
             }
 
+            constexpr explicit(!(hud::is_convertible_v<const hud::pair<key_type, value_type> &, hud::pair<key_type, value_type>>))
+                slot(const slot &other) noexcept
+            requires(hud::is_nothrow_copy_constructible_v<hud::pair<key_type, value_type>>)
+            = default;
+
+            template<typename u_key_t = key_t, typename u_value_t = value_t>
+            requires(hud::is_copy_constructible_v<hud::pair<key_type, value_type>, hud::pair<u_key_t, u_value_t>>)
+            constexpr explicit(!(hud::is_convertible_v<const hud::pair<key_type, value_type> &, hud::pair<u_key_t, u_value_t>>))
+                slot(const slot<u_key_t, u_value_t> &other) noexcept
+                : element_(other.element_)
+            {
+                static_assert(hud::is_nothrow_copy_constructible_v<key_t, u_key_t>, "key_t(const u_key_t&) copy constructor is throwable. slot is not designed to allow throwable copy constructible components");
+                static_assert(hud::is_nothrow_copy_constructible_v<value_t, u_value_t>, "value_t(const u_value_t&) copy constructor is throwable. slot is not designed to allow throwable copy constructible components");
+            }
+
             [[nodiscard]] constexpr const key_type &key() noexcept
             {
                 return hud::get<0>(element_);
@@ -74,6 +91,10 @@ namespace hud
                 return hud::get<idx_to_reach>(hud::forward<const slot>(s).element_);
             }
 
+        private:
+            template<typename u_key_t, typename u_value_t>
+            friend struct slot;
+
         private:
             hud::pair<key_type, value_type> element_;
         };

interface/core/traits/is_convertible.h

@@ -44,7 +44,10 @@ namespace hud
 
 #endif
 
-    /** Equivalent of hud::is_convertible<from_t,to_t>::value. */
+    /**
+     * Checks whether from_t is implicitly convertible to to_t.
+     * Equivalent of hud::is_convertible<from_t,to_t>::value.
+     * */
     template<typename from_t, typename to_t>
     inline constexpr bool is_convertible_v = hud::is_convertible<from_t, to_t>::value;