[FAB-1661] Remove shadow variable declarations

https://jira.hyperledger.org/browse/FAB-1661

This changeset removes a few shadow variable declarations that have crept
in the `kafka` package.

Change-Id: Ie3a763917b4d6e33320dd2ba037f92fbae8ae078
Signed-off-by: Kostas Christidis <[email protected]>

Author: kchristidis

orderer/kafka/producer_mock_test.go

@@ -62,19 +62,18 @@ func mockNewProducer(t *testing.T, cp ChainPartition, offset int64, disk chan *a
 func (mp *mockProducerImpl) Send(cp ChainPartition, payload []byte) error {
 	mp.producer.ExpectSendMessageWithCheckerFunctionAndSucceed(mp.checker)
 	mp.producedOffset++ // This is the offset that will be assigned to the sent message
-	_, ofs, err := mp.producer.SendMessage(newProducerMessage(cp, payload))
-	// We do NOT check the assigned partition because the mock
-	// producer always posts to partition 0 no matter what.
-	// This is a deficiency of the Kafka library that we use.
-	if err != nil || ofs != mp.producedOffset {
+	if _, ofs, err := mp.producer.SendMessage(newProducerMessage(cp, payload)); err != nil || ofs != mp.producedOffset {
+		// We do NOT check the assigned partition because the mock
+		// producer always posts to partition 0 no matter what.
+		// This is a deficiency of the Kafka library that we use.
 		mp.t.Fatal("Mock producer not functioning as expected")
 	}
 	msg := new(ab.KafkaMessage)
 	if err := proto.Unmarshal(payload, msg); err != nil {
 		mp.t.Fatalf("Failed to unmarshal message that reached producer's disk: %s", err)
 	}
 	mp.disk <- msg // Reaches the cluster's disk for that chain partition
-	return err
+	return nil
 }
 
 func (mp *mockProducerImpl) Close() error {

orderer/kafka/producer_test.go

@@ -19,13 +19,11 @@ package kafka
 import (
 	"testing"
 
-	"github.com/hyperledger/fabric/orderer/common/bootstrap/provisional"
 	ab "github.com/hyperledger/fabric/protos/orderer"
 	"github.com/hyperledger/fabric/protos/utils"
 )
 
 func TestProducerSend(t *testing.T) {
-	cp := newChainPartition(provisional.TestChainID, rawPartition)
 	mp := mockNewProducer(t, cp, testMiddleOffset, make(chan *ab.KafkaMessage))
 	defer testClose(t, mp)
 

orderer/kafka/util_test.go

@@ -24,8 +24,6 @@ import (
 )
 
 func TestProducerConfigMessageMaxBytes(t *testing.T) {
-	cp := newChainPartition(provisional.TestChainID, rawPartition)
-
 	broker := sarama.NewMockBroker(t, 1)
 	defer func() {
 		broker.Close()