Allow no delay publisher

components/delay/publisher.go

@@ -1,6 +1,10 @@
 package delay
 
-import "github.com/ThreeDotsLabs/watermill/message"
+import (
+	"errors"
+
+	"github.com/ThreeDotsLabs/watermill/message"
+)
 
 type DefaultDelayGeneratorParams struct {
 	Topic   string
@@ -12,6 +16,10 @@ type PublisherConfig struct {
 	// DefaultDelayGenerator is a function that generates the default delay for a message.
 	// If the message doesn't have the delay metadata set, the default delay will be applied.
 	DefaultDelayGenerator func(params DefaultDelayGeneratorParams) (Delay, error)
+
+	// AllowNoDelay allows publishing messages without a delay set.
+	// By default, the publisher returns an error when a message is published without a delay and no default delay generator is provided.
+	AllowNoDelay bool
 }
 
 // NewPublisher wraps a publisher with a delay mechanism.
@@ -63,6 +71,12 @@ func (p *publisher) applyDelay(topic string, msg *message.Message) error {
 			return err
 		}
 		Message(msg, delay)
+
+		return nil
+	}
+
+	if !p.config.AllowNoDelay {
+		return errors.New("message doesn't have a delay set")
 	}
 
 	return nil

components/delay/publisher_test.go

@@ -23,6 +23,11 @@ func TestPublisher(t *testing.T) {
 	pub, err := delay.NewPublisher(pubSub, delay.PublisherConfig{})
 	require.NoError(t, err)
 
+	pubAllowNoDelay, err := delay.NewPublisher(pubSub, delay.PublisherConfig{
+		AllowNoDelay: true,
+	})
+	require.NoError(t, err)
+
 	defaultDelayPub, err := delay.NewPublisher(pubSub, delay.PublisherConfig{
 		DefaultDelayGenerator: func(params delay.DefaultDelayGeneratorParams) (delay.Delay, error) {
 			return delay.For(1 * time.Second), nil
@@ -34,6 +39,7 @@ func TestPublisher(t *testing.T) {
 		name               string
 		publisher          message.Publisher
 		messageConstructor func(id string) *message.Message
+		expectedError      bool
 		expectedDelay      time.Duration
 	}{
 		{
@@ -42,6 +48,15 @@ func TestPublisher(t *testing.T) {
 			messageConstructor: func(id string) *message.Message {
 				return message.NewMessage(id, nil)
 			},
+			expectedError: true,
+			expectedDelay: 0,
+		},
+		{
+			name:      "no delay but allowed",
+			publisher: pubAllowNoDelay,
+			messageConstructor: func(id string) *message.Message {
+				return message.NewMessage(id, nil)
+			},
 			expectedDelay: 0,
 		},
 		{
@@ -124,8 +139,13 @@ func TestPublisher(t *testing.T) {
 
 			msg := testCase.messageConstructor(id)
 			err = testCase.publisher.Publish("test", msg)
-			require.NoError(t, err)
 
+			if testCase.expectedError {
+				require.Error(t, err)
+				return
+			}
+
+			require.NoError(t, err)
 			assertMessage(t, messages, id, testCase.expectedDelay)
 		})
 	}