wip: test http handler CT generation

Signed-off-by: Arthur Silva Sens <arthur.sens@coralogix.com>

prometheus/promhttp/http.go

@@ -379,6 +379,9 @@ type HandlerOpts struct {
 	// NOTE: This feature is experimental and not covered by OpenMetrics or Prometheus
 	// exposition format.
 	ProcessStartTime time.Time
+	// If true, Counters, Summaries and Histograms will be exposed with additional 
+	// information about the timestamp when a particular timeseries was first initialized.
+	EnableCreatedTimestamps bool
 }
 
 // gzipAccepted returns whether the client will accept gzip-encoded content.

prometheus/promhttp/http_test.go

@@ -17,6 +17,7 @@ import (
 	"bytes"
 	"errors"
 	"fmt"
+	"io/ioutil"
 	"log"
 	"net/http"
 	"net/http/httptest"
@@ -25,6 +26,7 @@ import (
 	"time"
 
 	dto "github.com/prometheus/client_model/go"
+	"google.golang.org/protobuf/proto"
 
 	"github.com/prometheus/client_golang/prometheus"
 )
@@ -331,3 +333,55 @@ func TestHandlerTimeout(t *testing.T) {
 
 	close(c.Block) // To not leak a goroutine.
 }
+
+func TestHandlerWithCreatedTimestamps(t *testing.T) {
+	reg := prometheus.NewRegistry()
+	handlerWithCT := HandlerFor(reg, HandlerOpts{EnableCreatedTimestamps: true})
+	handlerWithoutCT := HandlerFor(reg, HandlerOpts{EnableCreatedTimestamps: false})
+	wWithCT := httptest.NewRecorder()
+	wWithoutCT := httptest.NewRecorder()
+	counter := prometheus.NewCounterVec(prometheus.CounterOpts{
+		Name: "test",
+		Help: "help test",
+	}, []string{"label"})
+
+	reg.MustRegister(counter)
+	counter.WithLabelValues("test1").Inc()
+	counter.WithLabelValues("test2").Add(2)
+
+	request, _ := http.NewRequest("GET", "/", nil)
+	request.Header.Add("Accept", "application/vnd.google.protobuf;proto=io.prometheus.client.MetricFamily;encoding=delimited;q=0.8")
+
+	handlerWithCT.ServeHTTP(wWithCT, request)
+	rspWithCt := wWithCT.Result()
+	handlerWithoutCT.ServeHTTP(wWithoutCT, request)
+	rspWithoutCt := wWithoutCT.Result()
+
+	bodyWithCT, err := ioutil.ReadAll(rspWithCt.Body)
+	if err != nil {
+		t.Errorf("Error reading response body: %s", err.Error())
+	}
+	bodyWithoutCT, err := ioutil.ReadAll(rspWithoutCt.Body)
+	if err != nil {
+		t.Errorf("Error reading response body: %s", err.Error())
+	}
+
+	var mfWithCT, mfWithoutCT dto.MetricFamily
+	err = proto.Unmarshal(bodyWithCT, &mfWithCT)
+	if err != nil {
+		t.Errorf("Error unmarshaling response: %s", err.Error())
+	}
+
+	err = proto.Unmarshal(bodyWithoutCT, &mfWithoutCT)
+	if err != nil {
+		t.Errorf("Error unmarshaling response: %s", err.Error())
+	}
+
+	if mfWithCT.Metric[0].Counter.CreatedTimestamp == nil {
+		t.Error("expected created timestamp, but there isn't")
+	}
+
+	if mfWithoutCT.Metric[0].Counter.CreatedTimestamp != nil {
+		t.Error("Did not expected created timestamp, but there is")
+	}
+}