Added test for variant attributes.

Author: 5cript

nui/include/nui/frontend/event_system/observed_value.hpp

@@ -217,14 +217,14 @@ namespace Nui
         }
 
         template <typename T = ContainedT>
-        requires std::equality_comparable<T> && Fundamental<T>
+        requires std::equality_comparable_with<ContainedT, T> && Fundamental<T> && Fundamental<ContainedT>
         ModifiableObserved& operator=(T&& t)
         {
             return assignChecked(t);
         }
 
         template <typename T = ContainedT>
-        requires std::equality_comparable<T>
+        requires std::equality_comparable_with<ContainedT, T>
         ModifiableObserved& assignChecked(T&& other)
         {
             if (contained_ != other)

nui/test/nui/test_attributes.hpp

@@ -474,4 +474,42 @@ namespace Nui::Tests
         globalEventContext.executeActiveEventsImmediately();
         EXPECT_EQ(Nui::val::global("document")["body"]["attributes"]["id"].as<std::string>(), "B");
     }
+
+    TEST_F(TestAttributes, AttributeCanBeVariant1)
+    {
+        using Nui::Elements::div;
+        using Nui::Attributes::id;
+
+        std::variant<std::string, int> idValue{"A"};
+
+        render(div{id = idValue}());
+        EXPECT_EQ(Nui::val::global("document")["body"]["attributes"]["id"].as<std::string>(), "A");
+    }
+
+    TEST_F(TestAttributes, AttributeCanBeVariant2)
+    {
+        using Nui::Elements::div;
+        using Nui::Attributes::id;
+
+        std::variant<std::string, int> idValue{2};
+
+        render(div{id = idValue}());
+        EXPECT_EQ(Nui::val::global("document")["body"]["attributes"]["id"].as<long long>(), 2);
+    }
+
+    TEST_F(TestAttributes, AttributeCanBeObservedVariant)
+    {
+        using Nui::Elements::div;
+        using Nui::Attributes::id;
+
+        Observed<std::variant<std::string, int>> idValue{"A"};
+
+        render(div{id = idValue}());
+        EXPECT_EQ(Nui::val::global("document")["body"]["attributes"]["id"].as<std::string>(), "A");
+
+        idValue = 2;
+        globalEventContext.executeActiveEventsImmediately();
+
+        EXPECT_EQ(Nui::val::global("document")["body"]["attributes"]["id"].as<long long>(), 2);
+    }
 }