Create a MockCluster within Go for testing (@SourceFellows, @kkoehler, …

…confluentinc#729)

* Added MockCluster implementation which can be used for testing

* adjust documentation for mock cluster

* Added example for MockCluster

* Fixed naming

Co-authored-by: Magnus Edenhill <magnus@edenhill.se>

* fixed typo

Co-authored-by: Magnus Edenhill <magnus@edenhill.se>

* removed

Co-authored-by: Magnus Edenhill <magnus@edenhill.se>

* fixed comment

Co-authored-by: Magnus Edenhill <magnus@edenhill.se>

* adjust documentation

Co-authored-by: Magnus Edenhill <magnus@edenhill.se>

* adjustments regarding comments from Magnus

* fixed cleanup code for kafka configuration

* fixed destroy for C references

* fixed spaces

* removed call to `C.rd_kafka_conf_destroy(mc.cConf)` in close

* added docu for MockCluster type

* moved package statement into first line

* adjustments according to @edenhill comments

* Update kafka/mockcluster.go

Co-authored-by: Magnus Edenhill <magnus@edenhill.se>

* removed duplicate import

* removed the remark as suggested from @edelhill

* changed typedef from struct_rd_kafka_mock_cluster_s to rd_kafka_mock_cluster_t

Co-authored-by: Kristian Köhler <github@kkoehler.com>
Co-authored-by: Magnus Edenhill <magnus@edenhill.se>
Co-authored-by: Kristian Köhler <kkoehler@users.noreply.github.com>

examples/mockcluster_example/mockcluster.go

@@ -0,0 +1,95 @@
+package main
+
+/**
+ * Copyright 2022 Confluent Inc.
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ * http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+import (
+	"fmt"
+	"github.com/confluentinc/confluent-kafka-go/kafka"
+	"os"
+)
+
+func main() {
+
+	mockCluster, err := kafka.NewMockCluster(1)
+	if err != nil {
+		fmt.Printf("Failed to create MockCluster: %s\n", err)
+		os.Exit(1)
+	}
+	defer mockCluster.Close()
+
+	broker := mockCluster.BootstrapServers()
+
+	p, err := kafka.NewProducer(&kafka.ConfigMap{"bootstrap.servers": broker})
+
+	if err != nil {
+		fmt.Printf("Failed to create producer: %s\n", err)
+		os.Exit(1)
+	}
+
+	fmt.Printf("Created Producer %v\n", p)
+	deliveryChan := make(chan kafka.Event)
+
+	topic := "Test"
+	value := "Hello Go!"
+	err = p.Produce(&kafka.Message{
+		TopicPartition: kafka.TopicPartition{Topic: &topic, Partition: kafka.PartitionAny},
+		Value:          []byte(value),
+		Headers:        []kafka.Header{{Key: "myTestHeader", Value: []byte("header values are binary")}},
+	}, deliveryChan)
+
+	e := <-deliveryChan
+	m := e.(*kafka.Message)
+
+	if m.TopicPartition.Error != nil {
+		fmt.Printf("Delivery failed: %v\n", m.TopicPartition.Error)
+	} else {
+		fmt.Printf("Delivered message to topic %s [%d] at offset %v\n",
+			*m.TopicPartition.Topic, m.TopicPartition.Partition, m.TopicPartition.Offset)
+	}
+
+	close(deliveryChan)
+
+	c, err := kafka.NewConsumer(&kafka.ConfigMap{
+		"bootstrap.servers":     broker,
+		"broker.address.family": "v4",
+		"group.id":              "group",
+		"session.timeout.ms":    6000,
+		"auto.offset.reset":     "earliest"})
+
+	if err != nil {
+		fmt.Fprintf(os.Stderr, "Failed to create consumer: %s\n", err)
+		os.Exit(1)
+	}
+	defer c.Close()
+
+	fmt.Printf("Created Consumer %v\n", c)
+
+	err = c.SubscribeTopics([]string{topic}, nil)
+	if err != nil {
+		fmt.Fprintf(os.Stderr, "Failed to subscribe to consumer: %s\n", err)
+		os.Exit(1)
+	}
+
+	msg, err := c.ReadMessage(-1)
+	if err != nil {
+		fmt.Fprintf(os.Stderr, "Failed to read message: %s\n", err)
+		os.Exit(1)
+	}
+
+	fmt.Println("received message: ", string(msg.Value))
+
+}

kafka/adminapi.go

@@ -1,3 +1,5 @@
+package kafka
+
 /**
  * Copyright 2018 Confluent Inc.
  *
@@ -14,8 +16,6 @@
  * limitations under the License.
  */
 
-package kafka
-
 import (
 	"context"
 	"fmt"

kafka/adminoptions.go

@@ -1,3 +1,5 @@
+package kafka
+
 /**
  * Copyright 2018 Confluent Inc.
  *
@@ -14,8 +16,6 @@
  * limitations under the License.
  */
 
-package kafka
-
 import (
 	"fmt"
 	"time"

kafka/config_test.go

@@ -1,3 +1,5 @@
+package kafka
+
 /**
  * Copyright 2016 Confluent Inc.
  *
@@ -14,8 +16,6 @@
  * limitations under the License.
  */
 
-package kafka
-
 import (
 	"fmt"
 	"testing"

kafka/consumer_performance_test.go

@@ -1,3 +1,5 @@
+package kafka
+
 /**
  * Copyright 2016 Confluent Inc.
  *
@@ -14,8 +16,6 @@
  * limitations under the License.
  */
 
-package kafka
-
 import (
 	"fmt"
 	"math/rand"

kafka/consumer_test.go

@@ -1,3 +1,5 @@
+package kafka
+
 /**
  * Copyright 2016 Confluent Inc.
  *
@@ -14,8 +16,6 @@
  * limitations under the License.
  */
 
-package kafka
-
 import (
 	"fmt"
 	"os"

kafka/context.go

@@ -1,3 +1,5 @@
+package kafka
+
 /**
  * Copyright 2019 Confluent Inc.
  *
@@ -14,8 +16,6 @@
  * limitations under the License.
  */
 
-package kafka
-
 import (
 	"context"
 	"time"

kafka/error_test.go

@@ -1,3 +1,5 @@
+package kafka
+
 /**
  * Copyright 2019 Confluent Inc.
  *
@@ -14,8 +16,6 @@
  * limitations under the License.
  */
 
-package kafka
-
 import (
 	"strings"
 	"testing"

kafka/event_test.go

@@ -1,3 +1,5 @@
+package kafka
+
 /**
  * Copyright 2016 Confluent Inc.
  *
@@ -14,8 +16,6 @@
  * limitations under the License.
  */
 
-package kafka
-
 import (
 	"testing"
 )

kafka/header_test.go

@@ -1,3 +1,5 @@
+package kafka
+
 /**
  * Copyright 2016 Confluent Inc.
  *
@@ -14,8 +16,6 @@
  * limitations under the License.
  */
 
-package kafka
-
 import (
 	"testing"
 )

kafka/integration_test.go

@@ -1,3 +1,5 @@
+package kafka
+
 /**
  * Copyright 2016 Confluent Inc.
  *
@@ -14,8 +16,6 @@
  * limitations under the License.
  */
 
-package kafka
-
 import (
 	"context"
 	"encoding/binary"

kafka/kafka.go

@@ -1,3 +1,5 @@
+package kafka
+
 /**
  * Copyright 2016 Confluent Inc.
  *
@@ -20,7 +22,7 @@
 //
 // High-level Consumer
 //
-// * Decide if you want to read messages and events by calling `.Poll()` or 
+// * Decide if you want to read messages and events by calling `.Poll()` or
 // the deprecated option of using the `.Events()` channel. (If you want to use
 // `.Events()` channel then set `"go.events.channel.enable": true`).
 //
@@ -249,7 +251,6 @@
 // possible complications with blocking Poll() calls.
 //
 // Note: The Confluent Kafka Go client is safe for concurrent use.
-package kafka
 
 import (
 	"fmt"

kafka/kafka_test.go

@@ -1,3 +1,5 @@
+package kafka
+
 /**
  * Copyright 2016 Confluent Inc.
  *
@@ -14,8 +16,6 @@
  * limitations under the License.
  */
 
-package kafka
-
 import (
 	"testing"
 )