test: rework lib stuff to share common files

test/lib/dispatcher/shared/main.cpp

@@ -0,0 +1,28 @@
+#include <gtest/gtest.h>
+#include <entt/core/attribute.h>
+#include <entt/core/utility.hpp>
+#include <entt/signal/dispatcher.hpp>
+#include <entt/signal/sigh.hpp>
+#include "types.h"
+
+ENTT_API void trigger(entt::dispatcher &);
+
+struct listener {
+    void on(message msg) {
+        value = msg.payload;
+    }
+
+    int value{};
+};
+
+TEST(Lib, Dispatcher) {
+    entt::dispatcher dispatcher;
+    listener listener;
+
+    ASSERT_EQ(listener.value, 0);
+
+    dispatcher.sink<message>().connect<entt::overload<void(message)>(&listener::on)>(listener);
+    trigger(dispatcher);
+
+    ASSERT_EQ(listener.value, 42);
+}