snapshot of https://github.com/ThreeDotsLabs/watermill.git (master, 2026-09-15; blobs > 131072B omitted)

message/router/middleware/randomfail.go

@@ -0,0 +1,39 @@
+package middleware
+
+import (
+	"math/rand"
+
+	"github.com/ThreeDotsLabs/watermill/message"
+	"github.com/pkg/errors"
+)
+
+func shouldFail(probability float32) bool {
+	r := rand.Float32()
+	return r <= probability
+}
+
+// RandomFail makes the handler fail with an error based on random chance. Error probability should be in the range (0,1).
+func RandomFail(errorProbability float32) message.HandlerMiddleware {
+	return func(h message.HandlerFunc) message.HandlerFunc {
+		return func(message *message.Message) ([]*message.Message, error) {
+			if shouldFail(errorProbability) {
+				return nil, errors.New("random fail occurred")
+			}
+
+			return h(message)
+		}
+	}
+}
+
+// RandomPanic makes the handler panic based on random chance. Panic probability should be in the range (0,1).
+func RandomPanic(panicProbability float32) message.HandlerMiddleware {
+	return func(h message.HandlerFunc) message.HandlerFunc {
+		return func(message *message.Message) ([]*message.Message, error) {
+			if shouldFail(panicProbability) {
+				panic("random panic occurred")
+			}
+
+			return h(message)
+		}
+	}
+}