More precise shutdown testing

Don't defer any `Close` calls - it's much harder to debug if they fail, and if
the test exits prematurely the entire suite fails anyways.

Also fix one case where we were not checking the return value of
`producer.Close()`.

producer_test.go

@@ -100,8 +100,6 @@ func TestConcurrentSimpleProducer(t *testing.T) {
 func TestProducer(t *testing.T) {
 	broker1 := NewMockBroker(t, 1)
 	broker2 := NewMockBroker(t, 2)
-	defer broker1.Close()
-	defer broker2.Close()
 
 	response1 := new(MetadataResponse)
 	response1.AddBroker(broker2.Addr(), broker2.BrokerID())
@@ -116,7 +114,6 @@ func TestProducer(t *testing.T) {
 	if err != nil {
 		t.Fatal(err)
 	}
-	defer safeClose(t, client)
 
 	config := NewProducerConfig()
 	config.FlushMsgCount = 10
@@ -125,7 +122,6 @@ func TestProducer(t *testing.T) {
 	if err != nil {
 		t.Fatal(err)
 	}
-	defer safeClose(t, producer)
 
 	for i := 0; i < 10; i++ {
 		producer.Input() <- &MessageToSend{Topic: "my_topic", Key: nil, Value: StringEncoder(TestMessage), Metadata: i}
@@ -146,13 +142,16 @@ func TestProducer(t *testing.T) {
 			}
 		}
 	}
+
+	safeClose(t, producer)
+	safeClose(t, client)
+	broker2.Close()
+	broker1.Close()
 }
 
 func TestProducerMultipleFlushes(t *testing.T) {
 	broker1 := NewMockBroker(t, 1)
 	broker2 := NewMockBroker(t, 2)
-	defer broker1.Close()
-	defer broker2.Close()
 
 	response1 := new(MetadataResponse)
 	response1.AddBroker(broker2.Addr(), broker2.BrokerID())
@@ -169,7 +168,6 @@ func TestProducerMultipleFlushes(t *testing.T) {
 	if err != nil {
 		t.Fatal(err)
 	}
-	defer safeClose(t, client)
 
 	config := NewProducerConfig()
 	config.FlushMsgCount = 5
@@ -178,7 +176,6 @@ func TestProducerMultipleFlushes(t *testing.T) {
 	if err != nil {
 		t.Fatal(err)
 	}
-	defer producer.Close()
 
 	for flush := 0; flush < 3; flush++ {
 		for i := 0; i < 5; i++ {
@@ -198,15 +195,17 @@ func TestProducerMultipleFlushes(t *testing.T) {
 			}
 		}
 	}
+
+	safeClose(t, producer)
+	safeClose(t, client)
+	broker2.Close()
+	broker1.Close()
 }
 
 func TestProducerMultipleBrokers(t *testing.T) {
 	broker1 := NewMockBroker(t, 1)
 	broker2 := NewMockBroker(t, 2)
 	broker3 := NewMockBroker(t, 3)
-	defer broker1.Close()
-	defer broker2.Close()
-	defer broker3.Close()
 
 	response1 := new(MetadataResponse)
 	response1.AddBroker(broker2.Addr(), broker2.BrokerID())
@@ -227,7 +226,6 @@ func TestProducerMultipleBrokers(t *testing.T) {
 	if err != nil {
 		t.Fatal(err)
 	}
-	defer safeClose(t, client)
 
 	config := NewProducerConfig()
 	config.FlushMsgCount = 5
@@ -237,7 +235,6 @@ func TestProducerMultipleBrokers(t *testing.T) {
 	if err != nil {
 		t.Fatal(err)
 	}
-	defer safeClose(t, producer)
 
 	for i := 0; i < 10; i++ {
 		producer.Input() <- &MessageToSend{Topic: "my_topic", Key: nil, Value: StringEncoder(TestMessage)}
@@ -255,6 +252,12 @@ func TestProducerMultipleBrokers(t *testing.T) {
 			}
 		}
 	}
+
+	safeClose(t, producer)
+	safeClose(t, client)
+	broker3.Close()
+	broker2.Close()
+	broker1.Close()
 }
 
 func TestProducerFailureRetry(t *testing.T) {