fix: buildUniqueConsumerGroupId should not return just unknownhost wh…

…en an error happens

kafka.go

@@ -31,6 +31,13 @@ func (e *checkTimeoutError) Error() string {
 	return e.message
 }
 
+// hostnameProvider is a generic contract to get the hostname. We use the hostname
+// to build the consumer group identifier.
+type hostnameProvider func() (string, error)
+
+// hnProvider is the default hostname provider.
+var hnProvider hostnameProvider = os.Hostname
+
 // KafkaConfig is used for configuring the go-kafka check.
 type KafkaConfig struct {
 	BootstrapServers     string        // coma separated list of kafka brokers
@@ -120,13 +127,13 @@ func validateKafkaConfig(cfg *KafkaConfig) error {
 // same health topic that will be unused on every restart of our application so better to
 // have a periodic process to cleanup consumer groups in the kafka cluster.
 func buildUniqueConsumerGroupId() string {
-	hostname, err := os.Hostname()
+	hostname, err := hnProvider()
 	if err != nil {
-		return "unknownhost"
+		hostname = "unknownhost"
 	}
 
 	timestamp := time.Now().UnixNano()
-	uniqueID := fmt.Sprintf("%s-%s-%d", consumerGroupPrefix, hostname, timestamp)
+	uniqueID := fmt.Sprintf("%s@@%s@@%d", consumerGroupPrefix, hostname, timestamp)
 
 	return uniqueID
 }

kafka_test.go

@@ -2,9 +2,11 @@ package kafka
 
 import (
 	"context"
+	"errors"
 	"fmt"
 	"os"
 	"reflect"
+	"strings"
 	"testing"
 	"time"
 
@@ -42,6 +44,45 @@ func TestMain(m *testing.M) {
 	os.Exit(code)
 }
 
+func TestBuildUniqueConsumerGroupId(t *testing.T) {
+	realHostname, _ := os.Hostname()
+
+	type args struct {
+		hnProvider hostnameProvider
+	}
+	testcases := []struct {
+		name         string
+		args         args
+		wantHostname string
+	}{
+		{
+			name: "return the hostname",
+			args: args{
+				hnProvider: os.Hostname,
+			},
+			wantHostname: realHostname,
+		},
+		{
+			name: "return unknownhost is an error happens",
+			args: args{
+				hnProvider: func() (string, error) {
+					return "", errors.New("unexpected error")
+				},
+			},
+			wantHostname: "unknownhost",
+		},
+	}
+
+	for _, tc := range testcases {
+		t.Run(tc.name, func(t *testing.T) {
+			hnProvider = tc.args.hnProvider
+			cg := buildUniqueConsumerGroupId()
+			substrings := strings.Split(cg, "@@")
+			assert.Equal(t, tc.wantHostname, substrings[1])
+		})
+	}
+}
+
 func TestNewKafka(t *testing.T) {
 	ctx := context.Background()
 	bootStrapServers, _ := kafkaContainer.Brokers(ctx)