Added convenience method StoreMessage that calls StoreOffsets (@finnc…

…olman, #676)

* Added convenience method StoreMessage that calls StoreOffsets

* Added '.' at the end of the comment

* Added Offset less than 0 check

* Moved the check to the correct method

Co-authored-by: Finn Colman <finn.colman@modicagroup.com>

kafka/consumer.go

@@ -292,6 +292,20 @@ func (c *Consumer) StoreOffsets(offsets []TopicPartition) (storedOffsets []Topic
 	return storedOffsets, nil
 }
 
+// StoreMessage stores offset based on the provided message.
+// This is a convenience method that uses StoreOffsets to do the actual work.
+func (c *Consumer) StoreMessage(m *Message) (storedOffsets []TopicPartition, err error) {
+	if m.TopicPartition.Error != nil {
+		return nil, newErrorFromString(ErrInvalidArg, "Can't store errored message")
+	}
+	if m.TopicPartition.Offset < 0 {
+		return nil, newErrorFromString(ErrInvalidArg, "Can't store message with offset less than 0")
+	}
+	offsets := []TopicPartition{m.TopicPartition}
+	offsets[0].Offset++
+	return c.StoreOffsets(offsets)
+}
+
 // Seek seeks the given topic partitions using the offset from the TopicPartition.
 //
 // If timeoutMs is not 0 the call will wait this long for the

kafka/consumer_test.go

@@ -85,6 +85,16 @@ func TestConsumerAPIs(t *testing.T) {
 		t.Errorf("StoreOffsets(empty) failed: %s", err)
 	}
 
+	// test StoreMessage doesn't fail either
+	stored, err = c.StoreMessage(&Message{TopicPartition: TopicPartition{Topic: &topic, Partition: 0, Offset: 1}})
+	if err != nil && err.(Error).Code() != ErrUnknownPartition {
+		t.Errorf("StoreMessage() failed: %s", err)
+		toppar := stored[0]
+		if toppar.Error != nil && toppar.Error.(Error).Code() == ErrUnknownPartition {
+			t.Errorf("StoreMessage() TopicPartition error: %s", toppar.Error)
+		}
+	}
+
 	topic1 := "gotest1"
 	topic2 := "gotest2"
 	err = c.Assign([]TopicPartition{{Topic: &topic1, Partition: 2},