test: common emitter test class

test/common/emitter.h

@@ -0,0 +1,14 @@
+#ifndef ENTT_COMMON_EMITTER_H
+#define ENTT_COMMON_EMITTER_H
+
+#include <entt/signal/emitter.hpp>
+
+namespace test {
+
+struct emitter: entt::emitter<emitter> {
+    using entt::emitter<emitter>::emitter;
+};
+
+} // namespace test
+
+#endif