Apply global and plugin level metric modifications before filtering (#5152)

internal/models/running_input_test.go

@@ -7,11 +7,43 @@ import (
 	"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 TestMakeMetricFilterAfterApplyingGlobalTags(t *testing.T) {
+	now := time.Now()
+	ri := NewRunningInput(&testInput{}, &InputConfig{
+		Filter: Filter{
+			TagInclude: []string{"b"},
+		},
+	})
+	require.NoError(t, ri.Config.Filter.Compile())
+	ri.SetDefaultTags(map[string]string{"a": "x", "b": "y"})
+
+	m, err := metric.New("cpu",
+		map[string]string{},
+		map[string]interface{}{
+			"value": 42,
+		},
+		now)
+	require.NoError(t, err)
+
+	actual := ri.MakeMetric(m)
+
+	expected, err := metric.New("cpu",
+		map[string]string{
+			"b": "y",
+		},
+		map[string]interface{}{
+			"value": 42,
+		},
+		now)
+	require.NoError(t, err)
+
+	testutil.RequireMetricEqual(t, expected, actual)
+}
+
 func TestMakeMetricNoFields(t *testing.T) {
 	now := time.Now()
 	ri := NewRunningInput(&testInput{}, &InputConfig{