test: rework lib stuff to share common files

test/lib/dispatcher/plugin/main.cpp

@@ -0,0 +1,35 @@
+#define CR_HOST
+
+#include <gtest/gtest.h>
+#include <cr.h>
+#include <entt/signal/dispatcher.hpp>
+#include <entt/signal/sigh.hpp>
+#include "types.h"
+
+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<&listener::on>(listener);
+
+    cr_plugin ctx;
+    cr_plugin_load(ctx, PLUGIN);
+
+    ctx.userdata = &dispatcher;
+    cr_plugin_update(ctx);
+
+    ASSERT_EQ(listener.value, 42);
+
+    dispatcher = {};
+    cr_plugin_close(ctx);
+}