output/json: Removed tainted field

The `metric.tainted` has been removed from the flushed struct because
metrics are flush only the first time a metric has been seen and tainted
will be updated only after so the tainted field's value hasn't been never different
from a null value.

output/json/json.go

@@ -183,13 +183,6 @@ func (o *Output) handleMetric(m *metrics.Metric, jw *jwriter.Writer) {
 		wrapped.Data.Thresholds = ts
 	}
 
-	// TODO: refactor after the other refactors
-	// in the metrics area will be completed.
-	//
-	// This parts can be racy because
-	// they are controlled and written from the metrics.Engine.
-	wrapped.Data.Tainted = m.Tainted
-
 	wrapped.MarshalEasyJSON(jw)
 	jw.RawByte('\n')
 }

output/json/json_test.go

@@ -82,10 +82,10 @@ func generateTestMetricSamples(t testing.TB) ([]metrics.SampleContainer, func(io
 		metrics.Sample{Time: time3, Metric: metric2, Value: float64(5), Tags: metrics.NewSampleTags(map[string]string{"tag3": "val3"})},
 	}
 	expected := []string{
-		`{"type":"Metric","data":{"name":"my_metric1","type":"gauge","contains":"default","tainted":null,"thresholds":["rate<0.01","p(99)<250"],"submetrics":[{"name":"my_metric1{a:1,b:2}","suffix":"a:1,b:2","tags":{"a":"1","b":"2"}}]},"metric":"my_metric1"}`,
+		`{"type":"Metric","data":{"name":"my_metric1","type":"gauge","contains":"default","thresholds":["rate<0.01","p(99)<250"],"submetrics":[{"name":"my_metric1{a:1,b:2}","suffix":"a:1,b:2","tags":{"a":"1","b":"2"}}]},"metric":"my_metric1"}`,
 		`{"type":"Point","data":{"time":"2021-02-24T13:37:10Z","value":1,"tags":{"tag1":"val1"}},"metric":"my_metric1"}`,
 		`{"type":"Point","data":{"time":"2021-02-24T13:37:10Z","value":2,"tags":{"tag2":"val2"}},"metric":"my_metric1"}`,
-		`{"type":"Metric","data":{"name":"my_metric2","type":"counter","contains":"data","tainted":null,"thresholds":[],"submetrics":null},"metric":"my_metric2"}`,
+		`{"type":"Metric","data":{"name":"my_metric2","type":"counter","contains":"data","thresholds":[],"submetrics":null},"metric":"my_metric2"}`,
 		`{"type":"Point","data":{"time":"2021-02-24T13:37:20Z","value":3,"tags":{"key":"val"}},"metric":"my_metric2"}`,
 		`{"type":"Point","data":{"time":"2021-02-24T13:37:20Z","value":4,"tags":{"key":"val"}},"metric":"my_metric1"}`,
 		`{"type":"Point","data":{"time":"2021-02-24T13:37:30Z","value":5,"tags":{"tag3":"val3"}},"metric":"my_metric2"}`,

output/json/wrapper.go

@@ -24,7 +24,6 @@ import (
 	"time"
 
 	"go.k6.io/k6/metrics"
-	"gopkg.in/guregu/null.v3"
 )
 
 //go:generate easyjson -pkg -no_std_marshalers -gen_build_flags -mod=mod .
@@ -60,7 +59,6 @@ type metricEnvelope struct {
 		Name       string               `json:"name"`
 		Type       metrics.MetricType   `json:"type"`
 		Contains   metrics.ValueType    `json:"contains"`
-		Tainted    null.Bool            `json:"tainted"`
 		Thresholds metrics.Thresholds   `json:"thresholds"`
 		Submetrics []*metrics.Submetric `json:"submetrics"`
 	} `json:"data"`