Ignore fields with NaN or Inf floats in the JSON serializer (#7426)

plugins/serializers/json/json_test.go

@@ -2,14 +2,15 @@ package json
 
 import (
 	"fmt"
+	"math"
 	"testing"
 	"time"
 
-	"github.com/stretchr/testify/assert"
-	"github.com/stretchr/testify/require"
-
 	"github.com/influxdata/telegraf"
 	"github.com/influxdata/telegraf/metric"
+	"github.com/influxdata/telegraf/testutil"
+	"github.com/stretchr/testify/assert"
+	"github.com/stretchr/testify/require"
 )
 
 func MustMetric(v telegraf.Metric, err error) telegraf.Metric {
@@ -193,3 +194,42 @@ func TestSerializeBatch(t *testing.T) {
 	require.NoError(t, err)
 	require.Equal(t, []byte(`{"metrics":[{"fields":{"value":42},"name":"cpu","tags":{},"timestamp":0},{"fields":{"value":42},"name":"cpu","tags":{},"timestamp":0}]}`), buf)
 }
+
+func TestSerializeBatchSkipInf(t *testing.T) {
+	metrics := []telegraf.Metric{
+		testutil.MustMetric(
+			"cpu",
+			map[string]string{},
+			map[string]interface{}{
+				"inf":       math.Inf(1),
+				"time_idle": 42,
+			},
+			time.Unix(0, 0),
+		),
+	}
+
+	s, err := NewSerializer(0)
+	require.NoError(t, err)
+	buf, err := s.SerializeBatch(metrics)
+	require.NoError(t, err)
+	require.Equal(t, []byte(`{"metrics":[{"fields":{"time_idle":42},"name":"cpu","tags":{},"timestamp":0}]}`), buf)
+}
+
+func TestSerializeBatchSkipInfAllFields(t *testing.T) {
+	metrics := []telegraf.Metric{
+		testutil.MustMetric(
+			"cpu",
+			map[string]string{},
+			map[string]interface{}{
+				"inf": math.Inf(1),
+			},
+			time.Unix(0, 0),
+		),
+	}
+
+	s, err := NewSerializer(0)
+	require.NoError(t, err)
+	buf, err := s.SerializeBatch(metrics)
+	require.NoError(t, err)
+	require.Equal(t, []byte(`{"metrics":[{"fields":{},"name":"cpu","tags":{},"timestamp":0}]}`), buf)
+}