Update tests to compensate for the size of the header

Issue: segmentio/kafka-go#1050
PR: segmentio/kafka-go#1132
Release: https://github.com/segmentio/kafka-go/releases/tag/v0.4.41

writer_test.go

@@ -87,13 +87,13 @@ func TestProduce(t *testing.T) {
 	metricsValues := test.getCounterMetricsValues()
 	assert.Equal(t, 2.0, metricsValues[test.module.metrics.WriterWrites.Name])
 	assert.Equal(t, 2.0, metricsValues[test.module.metrics.WriterMessages.Name])
-	assert.Equal(t, 64.0, metricsValues[test.module.metrics.WriterBytes.Name])
+	assert.Equal(t, 66.0, metricsValues[test.module.metrics.WriterBytes.Name])
 	assert.Equal(t, 0.0, metricsValues[test.module.metrics.WriterErrors.Name])
 	assert.GreaterOrEqual(t, 1.0, metricsValues[test.module.metrics.WriterWriteTime.Name])
 	assert.Equal(t, 0.0, metricsValues[test.module.metrics.WriterWaitTime.Name])
 	assert.Equal(t, 0.0, metricsValues[test.module.metrics.WriterRetries.Name])
 	assert.Equal(t, 1.0, metricsValues[test.module.metrics.WriterBatchSize.Name])
-	assert.Equal(t, 32.0, metricsValues[test.module.metrics.WriterBatchBytes.Name])
+	assert.Equal(t, 33.0, metricsValues[test.module.metrics.WriterBatchBytes.Name])
 	assert.Equal(t, 0.0, metricsValues[test.module.metrics.WriterMaxAttempts.Name])
 	assert.Equal(t, 0.0, metricsValues[test.module.metrics.WriterMaxBatchSize.Name])
 	assert.Equal(t, 0.0, metricsValues[test.module.metrics.WriterBatchTimeout.Name])
@@ -145,7 +145,7 @@ func TestProduceWithoutKey(t *testing.T) {
 	metricsValues := test.getCounterMetricsValues()
 	assert.Equal(t, 0.0, metricsValues[test.module.metrics.WriterErrors.Name])
 	// Notice the smaller size because the key is not present (64 -> 56).
-	assert.Equal(t, 56.0, metricsValues[test.module.metrics.WriterBytes.Name])
+	assert.Equal(t, 58.0, metricsValues[test.module.metrics.WriterBytes.Name])
 	assert.Equal(t, 2.0, metricsValues[test.module.metrics.WriterMessages.Name])
 	assert.Equal(t, 2.0, metricsValues[test.module.metrics.WriterWrites.Name])
 }
@@ -237,7 +237,7 @@ func TestProduceJSON(t *testing.T) {
 	// Check if one message was produced.
 	metricsValues := test.getCounterMetricsValues()
 	assert.Equal(t, 0.0, metricsValues[test.module.metrics.WriterErrors.Name])
-	assert.Equal(t, 39, int(metricsValues[test.module.metrics.WriterBytes.Name]))
+	assert.Equal(t, 40, int(metricsValues[test.module.metrics.WriterBytes.Name]))
 	assert.Equal(t, 1.0, metricsValues[test.module.metrics.WriterMessages.Name])
 	assert.Equal(t, 1.0, metricsValues[test.module.metrics.WriterWrites.Name])
 }
@@ -295,7 +295,7 @@ func TestWriterClass(t *testing.T) {
 		// Check if one message was produced.
 		metricsValues := test.getCounterMetricsValues()
 		assert.Equal(t, 0.0, metricsValues[test.module.metrics.WriterErrors.Name])
-		assert.Equal(t, 30, int(metricsValues[test.module.metrics.WriterBytes.Name]))
+		assert.Equal(t, 31, int(metricsValues[test.module.metrics.WriterBytes.Name]))
 		assert.Equal(t, 1.0, metricsValues[test.module.metrics.WriterMessages.Name])
 		assert.Equal(t, 1.0, metricsValues[test.module.metrics.WriterWrites.Name])
 	})