improved code coverage

wrappers.go

@@ -1,8 +1,7 @@
 package gubgub
 
 // Forever wrapper makes it more explicit that a subscriber will never stop consuming messages.
-// This helps avoiding subscribers that always return true which, depending on their size, might
-// not be immediately clear.
+// This helps avoiding subscribers that always return TRUE.
 func Forever[T any](fn func(T)) Subscriber[T] {
 	return func(msg T) bool {
 		fn(msg)
@@ -10,7 +9,17 @@ func Forever[T any](fn func(T)) Subscriber[T] {
 	}
 }
 
-// NoOp creates a subscriber that does absolutely nothing forever. This is mostly useful for testing.
+// Once returns a subscriber that will consume only one message.
+// This helps avoiding subscribers that always return FALSE.
+func Once[T any](fn func(T)) Subscriber[T] {
+	return func(t T) bool {
+		fn(t)
+		return false
+	}
+}
+
+// NoOp creates a subscriber that does absolutely nothing forever.
+// This is mostly useful for testing.
 func NoOp[T any]() Subscriber[T] {
 	return func(_ T) bool { return true }
 }