Last touches (readability and consistency)

Changes:

* Comments for "now" are more explicit and not inlined.
* populateMetrics is simpler and bit more efficient without timestamp to time to timestamp conversionts for more common code.
* Test consistency and simplicity - the fewer variables the better.
* Fixed inconsistency for v2 and MetricVec - let's pass opt.now consistently.
* We don't need TestCounterXXXTimestamp - we test CT in many other places already.
* Added more involved test for counter vectors with created timestamp.
* Refactored normalization for simplicity.
* Make histogram, summaries now consistent.
* Simplified histograms CT flow and implemented proper CT on reset.

TODO for next PRs:
* NewConstSummary and NewConstHistogram - ability to specify CTs there.

Signed-off-by: bwplotka <bwplotka@gmail.com>

prometheus/counter.go

@@ -115,7 +115,8 @@ type counter struct {
 	labelPairs []*dto.LabelPair
 	exemplar   atomic.Value // Containing nil or a *dto.Exemplar.
 
-	now func() time.Time // For testing, all constructors put time.Now() here.
+	// now is for testing purposes, by default it's time.Now.
+	now func() time.Time
 }
 
 func (c *counter) Desc() *Desc {
@@ -165,9 +166,7 @@ func (c *counter) Write(out *dto.Metric) error {
 		exemplar = e.(*dto.Exemplar)
 	}
 	val := c.get()
-
+	return populateMetric(CounterValue, val, c.labelPairs, exemplar, out, c.createdTs)
-	ct := c.createdTs.AsTime()
-	return populateMetric(CounterValue, val, c.labelPairs, exemplar, out, &ct)
 }
 
 func (c *counter) updateExemplar(v float64, l Labels) {
@@ -215,7 +214,7 @@ func (v2) NewCounterVec(opts CounterVecOpts) *CounterVec {
 			if len(lvs) != len(desc.variableLabels.names) {
 				panic(makeInconsistentCardinalityError(desc.fqName, desc.variableLabels.names, lvs))
 			}
-			result := &counter{desc: desc, labelPairs: MakeLabelPairs(desc, lvs), now: time.Now}
+			result := &counter{desc: desc, labelPairs: MakeLabelPairs(desc, lvs), now: opts.now}
 			result.init(result) // Init self-collection.
 			result.createdTs = timestamppb.New(opts.now())
 			return result

prometheus/counter_test.go

@@ -27,12 +27,12 @@ import (
 
 func TestCounterAdd(t *testing.T) {
 	now := time.Now()
-	nowFn := func() time.Time { return now }
+
 	counter := NewCounter(CounterOpts{
 		Name:        "test",
 		Help:        "test help",
 		ConstLabels: Labels{"a": "1", "b": "2"},
-		now:         nowFn,
+		now:         func() time.Time { return now },
 	}).(*counter)
 	counter.Inc()
 	if expected, got := 0.0, math.Float64frombits(counter.valBits); expected != got {
@@ -71,7 +71,7 @@ func TestCounterAdd(t *testing.T) {
 		},
 		Counter: &dto.Counter{
 			Value:            proto.Float64(67.42),
-			CreatedTimestamp: timestamppb.New(nowFn()),
+			CreatedTimestamp: timestamppb.New(now),
 		},
 	}
 	if !proto.Equal(expected, m) {
@@ -146,11 +146,11 @@ func expectPanic(t *testing.T, op func(), errorMsg string) {
 
 func TestCounterAddInf(t *testing.T) {
 	now := time.Now()
-	nowFn := func() time.Time { return now }
+
 	counter := NewCounter(CounterOpts{
 		Name: "test",
 		Help: "test help",
-		now:  nowFn,
+		now:  func() time.Time { return now },
 	}).(*counter)
 
 	counter.Inc()
@@ -183,7 +183,7 @@ func TestCounterAddInf(t *testing.T) {
 	expected := &dto.Metric{
 		Counter: &dto.Counter{
 			Value:            proto.Float64(math.Inf(1)),
-			CreatedTimestamp: timestamppb.New(nowFn()),
+			CreatedTimestamp: timestamppb.New(now),
 		},
 	}
 
@@ -194,11 +194,11 @@ func TestCounterAddInf(t *testing.T) {
 
 func TestCounterAddLarge(t *testing.T) {
 	now := time.Now()
-	nowFn := func() time.Time { return now }
+
 	counter := NewCounter(CounterOpts{
 		Name: "test",
 		Help: "test help",
-		now:  nowFn,
+		now:  func() time.Time { return now },
 	}).(*counter)
 
 	// large overflows the underlying type and should therefore be stored in valBits.
@@ -217,7 +217,7 @@ func TestCounterAddLarge(t *testing.T) {
 	expected := &dto.Metric{
 		Counter: &dto.Counter{
 			Value:            proto.Float64(large),
-			CreatedTimestamp: timestamppb.New(nowFn()),
+			CreatedTimestamp: timestamppb.New(now),
 		},
 	}
 
@@ -228,12 +228,13 @@ func TestCounterAddLarge(t *testing.T) {
 
 func TestCounterAddSmall(t *testing.T) {
 	now := time.Now()
-	nowFn := func() time.Time { return now }
+
 	counter := NewCounter(CounterOpts{
 		Name: "test",
 		Help: "test help",
-		now:  nowFn,
+		now:  func() time.Time { return now },
 	}).(*counter)
+
 	small := 0.000000000001
 	counter.Add(small)
 	if expected, got := small, math.Float64frombits(counter.valBits); expected != got {
@@ -249,7 +250,7 @@ func TestCounterAddSmall(t *testing.T) {
 	expected := &dto.Metric{
 		Counter: &dto.Counter{
 			Value:            proto.Float64(small),
-			CreatedTimestamp: timestamppb.New(nowFn()),
+			CreatedTimestamp: timestamppb.New(now),
 		},
 	}
 
@@ -264,8 +265,8 @@ func TestCounterExemplar(t *testing.T) {
 	counter := NewCounter(CounterOpts{
 		Name: "test",
 		Help: "test help",
+		now:  func() time.Time { return now },
 	}).(*counter)
-	counter.now = func() time.Time { return now }
 
 	ts := timestamppb.New(now)
 	if err := ts.CheckValid(); err != nil {
@@ -317,39 +318,71 @@ func TestCounterExemplar(t *testing.T) {
 	}
 }
 
-func TestCounterCreatedTimestamp(t *testing.T) {
+func TestCounterVecCreatedTimestampWithDeletes(t *testing.T) {
 	now := time.Now()
-	counter := NewCounter(CounterOpts{
-		Name: "test",
-		Help: "test help",
-		now:  func() time.Time { return now },
-	})
 
-	var metric dto.Metric
-	if err := counter.Write(&metric); err != nil {
-		t.Fatal(err)
-	}
-
-	if metric.Counter.CreatedTimestamp.AsTime().Unix() != now.Unix() {
-		t.Errorf("expected created timestamp %d, got %d", now.Unix(), metric.Counter.CreatedTimestamp.AsTime().Unix())
-	}
-}
-
-func TestCounterVecCreatedTimestamp(t *testing.T) {
-	now := time.Now()
 	counterVec := NewCounterVec(CounterOpts{
 		Name: "test",
 		Help: "test help",
 		now:  func() time.Time { return now },
 	}, []string{"label"})
-	counter := counterVec.WithLabelValues("value")
 
-	var metric dto.Metric
+	// First use of "With" should populate CT.
-	if err := counter.Write(&metric); err != nil {
+	counterVec.WithLabelValues("1")
-		t.Fatal(err)
+	expected := map[string]time.Time{"1": now}
-	}
 
-	if metric.Counter.CreatedTimestamp.AsTime().Unix() != now.Unix() {
+	now = now.Add(1 * time.Hour)
-		t.Errorf("expected created timestamp %d, got %d", now.Unix(), metric.Counter.CreatedTimestamp.AsTime().Unix())
+	expectCTsForMetricVecValues(t, counterVec.MetricVec, dto.MetricType_COUNTER, expected)
+
+	// Two more labels at different times.
+	counterVec.WithLabelValues("2")
+	expected["2"] = now
+
+	now = now.Add(1 * time.Hour)
+
+	counterVec.WithLabelValues("3")
+	expected["3"] = now
+
+	now = now.Add(1 * time.Hour)
+	expectCTsForMetricVecValues(t, counterVec.MetricVec, dto.MetricType_COUNTER, expected)
+
+	// Recreate metric instance should reset created timestamp to now.
+	counterVec.DeleteLabelValues("1")
+	counterVec.WithLabelValues("1")
+	expected["1"] = now
+
+	now = now.Add(1 * time.Hour)
+	expectCTsForMetricVecValues(t, counterVec.MetricVec, dto.MetricType_COUNTER, expected)
+}
+
+func expectCTsForMetricVecValues(t testing.TB, vec *MetricVec, typ dto.MetricType, ctsPerLabelValue map[string]time.Time) {
+	t.Helper()
+
+	for val, ct := range ctsPerLabelValue {
+		var metric dto.Metric
+		m, err := vec.GetMetricWithLabelValues(val)
+		if err != nil {
+			t.Fatal(err)
+		}
+
+		if err := m.Write(&metric); err != nil {
+			t.Fatal(err)
+		}
+
+		var gotTs time.Time
+		switch typ {
+		case dto.MetricType_COUNTER:
+			gotTs = metric.Counter.CreatedTimestamp.AsTime()
+		case dto.MetricType_HISTOGRAM:
+			gotTs = metric.Histogram.CreatedTimestamp.AsTime()
+		case dto.MetricType_SUMMARY:
+			gotTs = metric.Summary.CreatedTimestamp.AsTime()
+		default:
+			t.Fatalf("unknown metric type %v", typ)
+		}
+
+		if !gotTs.Equal(ct) {
+			t.Errorf("expected created timestamp for counter with label value %q: %s, got %s", val, ct, gotTs)
+		}
 	}
 }

prometheus/example_metricvec_test.go

@@ -14,6 +14,8 @@
 package prometheus_test
 
 import (
+	"fmt"
+
 	"google.golang.org/protobuf/proto"
 
 	dto "github.com/prometheus/client_model/go"
@@ -124,7 +126,7 @@ func ExampleMetricVec() {
 	if err != nil || len(metricFamilies) != 1 {
 		panic("unexpected behavior of custom test registry")
 	}
-	printlnNormalized(metricFamilies[0])
+	fmt.Println(toNormalizedJSON(metricFamilies[0]))
 
 	// Output:
 	// {"name":"library_version_info","help":"Versions of the libraries used in this binary.","type":"GAUGE","metric":[{"label":[{"name":"library","value":"k8s.io/client-go"},{"name":"version","value":"0.18.8"}],"gauge":{"value":1}},{"label":[{"name":"library","value":"prometheus/client_golang"},{"name":"version","value":"1.7.1"}],"gauge":{"value":1}}]}

prometheus/examples_test.go

@@ -153,6 +153,22 @@ func ExampleCounterVec() {
 	httpReqs.DeleteLabelValues("200", "GET")
 	// Same thing with the more verbose Labels syntax.
 	httpReqs.Delete(prometheus.Labels{"method": "GET", "code": "200"})
+
+	// Just for demonstration, let's check the state of the counter vector
+	// by registering it with a custom registry and then let it collect the
+	// metrics.
+	reg := prometheus.NewRegistry()
+	reg.MustRegister(httpReqs)
+
+	metricFamilies, err := reg.Gather()
+	if err != nil || len(metricFamilies) != 1 {
+		panic("unexpected behavior of custom test registry")
+	}
+
+	fmt.Println(toNormalizedJSON(sanitizeMetricFamily(metricFamilies[0])))
+
+	// Output:
+	// {"name":"http_requests_total","help":"How many HTTP requests processed, partitioned by status code and HTTP method.","type":"COUNTER","metric":[{"label":[{"name":"code","value":"404"},{"name":"method","value":"POST"}],"counter":{"value":42,"createdTimestamp":"1970-01-01T00:00:10Z"}}]}
 }
 
 func ExampleRegister() {
@@ -319,13 +335,11 @@ func ExampleSummary() {
 	// internally).
 	metric := &dto.Metric{}
 	temps.Write(metric)
-	// We remove CreatedTimestamp just to make sure the assert below works.
-	metric.Summary.CreatedTimestamp = nil
 
-	printlnNormalized(metric)
+	fmt.Println(toNormalizedJSON(sanitizeMetric(metric)))
 
 	// Output:
-	// {"summary":{"sampleCount":"1000","sampleSum":29969.50000000001,"quantile":[{"quantile":0.5,"value":31.1},{"quantile":0.9,"value":41.3},{"quantile":0.99,"value":41.9}]}}
+	// {"summary":{"sampleCount":"1000","sampleSum":29969.50000000001,"quantile":[{"quantile":0.5,"value":31.1},{"quantile":0.9,"value":41.3},{"quantile":0.99,"value":41.9}],"createdTimestamp":"1970-01-01T00:00:10Z"}}
 }
 
 func ExampleSummaryVec() {
@@ -357,15 +371,11 @@ func ExampleSummaryVec() {
 	if err != nil || len(metricFamilies) != 1 {
 		panic("unexpected behavior of custom test registry")
 	}
-	// We remove CreatedTimestamp just to make sure the assert below works.
-	for _, m := range metricFamilies[0].Metric {
-		m.Summary.CreatedTimestamp = nil
-	}
 
-	printlnNormalized(metricFamilies[0])
+	fmt.Println(toNormalizedJSON(sanitizeMetricFamily(metricFamilies[0])))
 
 	// Output:
-	// {"name":"pond_temperature_celsius","help":"The temperature of the frog pond.","type":"SUMMARY","metric":[{"label":[{"name":"species","value":"leiopelma-hochstetteri"}],"summary":{"sampleCount":"0","sampleSum":0,"quantile":[{"quantile":0.5,"value":"NaN"},{"quantile":0.9,"value":"NaN"},{"quantile":0.99,"value":"NaN"}]}},{"label":[{"name":"species","value":"lithobates-catesbeianus"}],"summary":{"sampleCount":"1000","sampleSum":31956.100000000017,"quantile":[{"quantile":0.5,"value":32.4},{"quantile":0.9,"value":41.4},{"quantile":0.99,"value":41.9}]}},{"label":[{"name":"species","value":"litoria-caerulea"}],"summary":{"sampleCount":"1000","sampleSum":29969.50000000001,"quantile":[{"quantile":0.5,"value":31.1},{"quantile":0.9,"value":41.3},{"quantile":0.99,"value":41.9}]}}]}
+	// {"name":"pond_temperature_celsius","help":"The temperature of the frog pond.","type":"SUMMARY","metric":[{"label":[{"name":"species","value":"leiopelma-hochstetteri"}],"summary":{"sampleCount":"0","sampleSum":0,"quantile":[{"quantile":0.5,"value":"NaN"},{"quantile":0.9,"value":"NaN"},{"quantile":0.99,"value":"NaN"}],"createdTimestamp":"1970-01-01T00:00:10Z"}},{"label":[{"name":"species","value":"lithobates-catesbeianus"}],"summary":{"sampleCount":"1000","sampleSum":31956.100000000017,"quantile":[{"quantile":0.5,"value":32.4},{"quantile":0.9,"value":41.4},{"quantile":0.99,"value":41.9}],"createdTimestamp":"1970-01-01T00:00:10Z"}},{"label":[{"name":"species","value":"litoria-caerulea"}],"summary":{"sampleCount":"1000","sampleSum":29969.50000000001,"quantile":[{"quantile":0.5,"value":31.1},{"quantile":0.9,"value":41.3},{"quantile":0.99,"value":41.9}],"createdTimestamp":"1970-01-01T00:00:10Z"}}]}
 }
 
 func ExampleNewConstSummary() {
@@ -389,7 +399,7 @@ func ExampleNewConstSummary() {
 	// internally).
 	metric := &dto.Metric{}
 	s.Write(metric)
-	printlnNormalized(metric)
+	fmt.Println(toNormalizedJSON(metric))
 
 	// Output:
 	// {"label":[{"name":"code","value":"200"},{"name":"method","value":"get"},{"name":"owner","value":"example"}],"summary":{"sampleCount":"4711","sampleSum":403.34,"quantile":[{"quantile":0.5,"value":42.3},{"quantile":0.9,"value":323.3}]}}
@@ -412,13 +422,11 @@ func ExampleHistogram() {
 	// internally).
 	metric := &dto.Metric{}
 	temps.Write(metric)
-	// We remove CreatedTimestamp just to make sure the assert below works.
-	metric.Histogram.CreatedTimestamp = nil
 
-	printlnNormalized(metric)
+	fmt.Println(toNormalizedJSON(sanitizeMetric(metric)))
 
 	// Output:
-	// {"histogram":{"sampleCount":"1000","sampleSum":29969.50000000001,"bucket":[{"cumulativeCount":"192","upperBound":20},{"cumulativeCount":"366","upperBound":25},{"cumulativeCount":"501","upperBound":30},{"cumulativeCount":"638","upperBound":35},{"cumulativeCount":"816","upperBound":40}]}}
+	// {"histogram":{"sampleCount":"1000","sampleSum":29969.50000000001,"bucket":[{"cumulativeCount":"192","upperBound":20},{"cumulativeCount":"366","upperBound":25},{"cumulativeCount":"501","upperBound":30},{"cumulativeCount":"638","upperBound":35},{"cumulativeCount":"816","upperBound":40}],"createdTimestamp":"1970-01-01T00:00:10Z"}}
 }
 
 func ExampleNewConstHistogram() {
@@ -442,7 +450,7 @@ func ExampleNewConstHistogram() {
 	// internally).
 	metric := &dto.Metric{}
 	h.Write(metric)
-	printlnNormalized(metric)
+	fmt.Println(toNormalizedJSON(metric))
 
 	// Output:
 	// {"label":[{"name":"code","value":"200"},{"name":"method","value":"get"},{"name":"owner","value":"example"}],"histogram":{"sampleCount":"4711","sampleSum":403.34,"bucket":[{"cumulativeCount":"121","upperBound":25},{"cumulativeCount":"2403","upperBound":50},{"cumulativeCount":"3221","upperBound":100},{"cumulativeCount":"4233","upperBound":200}]}}
@@ -480,7 +488,7 @@ func ExampleNewConstHistogram_WithExemplar() {
 	// internally).
 	metric := &dto.Metric{}
 	h.Write(metric)
-	printlnNormalized(metric)
+	fmt.Println(toNormalizedJSON(metric))
 
 	// Output:
 	// {"label":[{"name":"code","value":"200"},{"name":"method","value":"get"},{"name":"owner","value":"example"}],"histogram":{"sampleCount":"4711","sampleSum":403.34,"bucket":[{"cumulativeCount":"121","upperBound":25,"exemplar":{"label":[{"name":"testName","value":"testVal"}],"value":24,"timestamp":"2006-01-02T15:04:05Z"}},{"cumulativeCount":"2403","upperBound":50,"exemplar":{"label":[{"name":"testName","value":"testVal"}],"value":42,"timestamp":"2006-01-02T15:04:05Z"}},{"cumulativeCount":"3221","upperBound":100,"exemplar":{"label":[{"name":"testName","value":"testVal"}],"value":89,"timestamp":"2006-01-02T15:04:05Z"}},{"cumulativeCount":"4233","upperBound":200,"exemplar":{"label":[{"name":"testName","value":"testVal"}],"value":157,"timestamp":"2006-01-02T15:04:05Z"}}]}}
@@ -642,7 +650,7 @@ func ExampleNewMetricWithTimestamp() {
 	// internally).
 	metric := &dto.Metric{}
 	s.Write(metric)
-	printlnNormalized(metric)
+	fmt.Println(toNormalizedJSON(metric))
 
 	// Output:
 	// {"gauge":{"value":298.15},"timestampMs":"1257894000012"}

prometheus/expvar_collector_test.go

@@ -81,7 +81,7 @@ func ExampleNewExpvarCollector() {
 		if !strings.Contains(m.Desc().String(), "expvar_memstats") {
 			metric.Reset()
 			m.Write(&metric)
-			metricStrings = append(metricStrings, protoToNormalizedJSON(&metric))
+			metricStrings = append(metricStrings, toNormalizedJSON(&metric))
 		}
 	}
 	sort.Strings(metricStrings)

prometheus/histogram.go

@@ -473,7 +473,8 @@ type HistogramOpts struct {
 	NativeHistogramMinResetDuration time.Duration
 	NativeHistogramMaxZeroThreshold float64
 
-	now func() time.Time // For testing, all constructors put time.Now() here.
+	// now is for testing purposes, by default it's time.Now.
+	now func() time.Time
 }
 
 // HistogramVecOpts bundles the options to create a HistogramVec metric.
@@ -522,6 +523,10 @@ func newHistogram(desc *Desc, opts HistogramOpts, labelValues ...string) Histogr
 		}
 	}
 
+	if opts.now == nil {
+		opts.now = time.Now
+	}
+
 	h := &histogram{
 		desc:                            desc,
 		upperBounds:                     opts.Buckets,
@@ -529,8 +534,8 @@ func newHistogram(desc *Desc, opts HistogramOpts, labelValues ...string) Histogr
 		nativeHistogramMaxBuckets:       opts.NativeHistogramMaxBucketNumber,
 		nativeHistogramMaxZeroThreshold: opts.NativeHistogramMaxZeroThreshold,
 		nativeHistogramMinResetDuration: opts.NativeHistogramMinResetDuration,
-		lastResetTime:                   time.Now(),
+		lastResetTime:                   opts.now(),
-		now:                             time.Now,
+		now:                             opts.now,
 	}
 	if len(h.upperBounds) == 0 && opts.NativeHistogramBucketFactor <= 1 {
 		h.upperBounds = DefBuckets
@@ -571,11 +576,7 @@ func newHistogram(desc *Desc, opts HistogramOpts, labelValues ...string) Histogr
 	atomic.StoreInt32(&h.counts[1].nativeHistogramSchema, h.nativeHistogramSchema)
 	h.exemplars = make([]atomic.Value, len(h.upperBounds)+1)
 
-	if opts.now == nil {
-		opts.now = time.Now
-	}
 	h.init(h) // Init self-collection.
-	h.createdTs = timestamppb.New(opts.now())
 	return h
 }
 
@@ -713,10 +714,11 @@ type histogram struct {
 	nativeHistogramMaxZeroThreshold float64
 	nativeHistogramMaxBuckets       uint32
 	nativeHistogramMinResetDuration time.Duration
-	lastResetTime                   time.Time // Protected by mtx.
+	// lastResetTime is protected by mtx. It is also used as created timestamp.
-	createdTs                       *timestamppb.Timestamp
+	lastResetTime time.Time
 
-	now func() time.Time // For testing, all constructors put time.Now() here.
+	// now is for testing purposes, by default it's time.Now.
+	now func() time.Time
 }
 
 func (h *histogram) Desc() *Desc {
@@ -758,7 +760,7 @@ func (h *histogram) Write(out *dto.Metric) error {
 		Bucket:           make([]*dto.Bucket, len(h.upperBounds)),
 		SampleCount:      proto.Uint64(count),
 		SampleSum:        proto.Float64(math.Float64frombits(atomic.LoadUint64(&coldCounts.sumBits))),
-		CreatedTimestamp: h.createdTs,
+		CreatedTimestamp: timestamppb.New(h.lastResetTime),
 	}
 	out.Histogram = his
 	out.Label = h.labelPairs

prometheus/histogram_test.go

@@ -416,8 +416,8 @@ func TestHistogramExemplar(t *testing.T) {
 		Name:    "test",
 		Help:    "test help",
 		Buckets: []float64{1, 2, 3, 4},
+		now:     func() time.Time { return now },
 	}).(*histogram)
-	histogram.now = func() time.Time { return now }
 
 	ts := timestamppb.New(now)
 	if err := ts.CheckValid(); err != nil {
@@ -470,7 +470,7 @@ func TestHistogramExemplar(t *testing.T) {
 
 func TestNativeHistogram(t *testing.T) {
 	now := time.Now()
-	nowFn := func() time.Time { return now }
+
 	scenarios := []struct {
 		name             string
 		observations     []float64 // With simulated interval of 1m.
@@ -501,7 +501,7 @@ func TestNativeHistogram(t *testing.T) {
 					{CumulativeCount: proto.Uint64(3), UpperBound: proto.Float64(5)},
 					{CumulativeCount: proto.Uint64(3), UpperBound: proto.Float64(10)},
 				},
-				CreatedTimestamp: timestamppb.New(nowFn()),
+				CreatedTimestamp: timestamppb.New(now),
 			},
 		},
 		{
@@ -513,7 +513,7 @@ func TestNativeHistogram(t *testing.T) {
 				Schema:           proto.Int32(3),
 				ZeroThreshold:    proto.Float64(2.938735877055719e-39),
 				ZeroCount:        proto.Uint64(0),
-				CreatedTimestamp: timestamppb.New(nowFn()),
+				CreatedTimestamp: timestamppb.New(now),
 			},
 		},
 		{
@@ -529,7 +529,7 @@ func TestNativeHistogram(t *testing.T) {
 				PositiveSpan: []*dto.BucketSpan{
 					{Offset: proto.Int32(0), Length: proto.Uint32(0)},
 				},
-				CreatedTimestamp: timestamppb.New(nowFn()),
+				CreatedTimestamp: timestamppb.New(now),
 			},
 		},
 		{
@@ -548,7 +548,7 @@ func TestNativeHistogram(t *testing.T) {
 					{Offset: proto.Int32(4), Length: proto.Uint32(1)},
 				},
 				PositiveDelta:    []int64{1, 0, 0},
-				CreatedTimestamp: timestamppb.New(nowFn()),
+				CreatedTimestamp: timestamppb.New(now),
 			},
 		},
 		{
@@ -565,7 +565,7 @@ func TestNativeHistogram(t *testing.T) {
 					{Offset: proto.Int32(0), Length: proto.Uint32(5)},
 				},
 				PositiveDelta:    []int64{1, -1, 2, -2, 2},
-				CreatedTimestamp: timestamppb.New(nowFn()),
+				CreatedTimestamp: timestamppb.New(now),
 			},
 		},
 		{
@@ -589,7 +589,7 @@ func TestNativeHistogram(t *testing.T) {
 					{Offset: proto.Int32(-2), Length: proto.Uint32(6)},
 				},
 				PositiveDelta:    []int64{2, 0, 0, 2, -1, -2},
-				CreatedTimestamp: timestamppb.New(nowFn()),
+				CreatedTimestamp: timestamppb.New(now),
 			},
 		},
 		{
@@ -611,7 +611,7 @@ func TestNativeHistogram(t *testing.T) {
 					{Offset: proto.Int32(-1), Length: proto.Uint32(4)},
 				},
 				PositiveDelta:    []int64{2, 2, 3, -6},
-				CreatedTimestamp: timestamppb.New(nowFn()),
+				CreatedTimestamp: timestamppb.New(now),
 			},
 		},
 		{
@@ -628,7 +628,7 @@ func TestNativeHistogram(t *testing.T) {
 					{Offset: proto.Int32(0), Length: proto.Uint32(5)},
 				},
 				NegativeDelta:    []int64{1, -1, 2, -2, 2},
-				CreatedTimestamp: timestamppb.New(nowFn()),
+				CreatedTimestamp: timestamppb.New(now),
 			},
 		},
 		{
@@ -649,7 +649,7 @@ func TestNativeHistogram(t *testing.T) {
 					{Offset: proto.Int32(0), Length: proto.Uint32(5)},
 				},
 				PositiveDelta:    []int64{1, -1, 2, -2, 2},
-				CreatedTimestamp: timestamppb.New(nowFn()),
+				CreatedTimestamp: timestamppb.New(now),
 			},
 		},
 		{
@@ -671,7 +671,7 @@ func TestNativeHistogram(t *testing.T) {
 					{Offset: proto.Int32(4), Length: proto.Uint32(1)},
 				},
 				PositiveDelta:    []int64{2},
-				CreatedTimestamp: timestamppb.New(nowFn()),
+				CreatedTimestamp: timestamppb.New(now),
 			},
 		},
 		{
@@ -688,7 +688,7 @@ func TestNativeHistogram(t *testing.T) {
 					{Offset: proto.Int32(0), Length: proto.Uint32(5)},
 				},
 				PositiveDelta:    []int64{1, -1, 2, -2, 2},
-				CreatedTimestamp: timestamppb.New(nowFn()),
+				CreatedTimestamp: timestamppb.New(now),
 			},
 		},
 		{
@@ -706,7 +706,7 @@ func TestNativeHistogram(t *testing.T) {
 					{Offset: proto.Int32(4092), Length: proto.Uint32(1)},
 				},
 				PositiveDelta:    []int64{1, -1, 2, -2, 2, -1},
-				CreatedTimestamp: timestamppb.New(nowFn()),
+				CreatedTimestamp: timestamppb.New(now),
 			},
 		},
 		{
@@ -727,7 +727,7 @@ func TestNativeHistogram(t *testing.T) {
 					{Offset: proto.Int32(0), Length: proto.Uint32(5)},
 				},
 				PositiveDelta:    []int64{1, -1, 2, -2, 2},
-				CreatedTimestamp: timestamppb.New(nowFn()),
+				CreatedTimestamp: timestamppb.New(now),
 			},
 		},
 		{
@@ -745,7 +745,7 @@ func TestNativeHistogram(t *testing.T) {
 					{Offset: proto.Int32(0), Length: proto.Uint32(5)},
 				},
 				PositiveDelta:    []int64{1, -1, 2, -2, 2},
-				CreatedTimestamp: timestamppb.New(nowFn()),
+				CreatedTimestamp: timestamppb.New(now),
 			},
 		},
 		{
@@ -763,7 +763,7 @@ func TestNativeHistogram(t *testing.T) {
 					{Offset: proto.Int32(0), Length: proto.Uint32(5)},
 				},
 				PositiveDelta:    []int64{1, 2, -1, -2, 1},
-				CreatedTimestamp: timestamppb.New(nowFn()),
+				CreatedTimestamp: timestamppb.New(now),
 			},
 		},
 		{
@@ -782,7 +782,7 @@ func TestNativeHistogram(t *testing.T) {
 					{Offset: proto.Int32(1), Length: proto.Uint32(7)},
 				},
 				PositiveDelta:    []int64{1, 1, -2, 2, -2, 0, 1},
-				CreatedTimestamp: timestamppb.New(nowFn()),
+				CreatedTimestamp: timestamppb.New(now),
 			},
 		},
 		{
@@ -801,7 +801,7 @@ func TestNativeHistogram(t *testing.T) {
 					{Offset: proto.Int32(2), Length: proto.Uint32(7)},
 				},
 				PositiveDelta:    []int64{2, -2, 2, -2, 0, 1, 0},
-				CreatedTimestamp: timestamppb.New(nowFn()),
+				CreatedTimestamp: timestamppb.New(now),
 			},
 		},
 		{
@@ -821,7 +821,7 @@ func TestNativeHistogram(t *testing.T) {
 					{Offset: proto.Int32(7), Length: proto.Uint32(2)},
 				},
 				PositiveDelta:    []int64{1, 0},
-				CreatedTimestamp: timestamppb.New(nowFn()),
+				CreatedTimestamp: timestamppb.New(now.Add(8 * time.Minute)), // We expect reset to happen after 8 observations.
 			},
 		},
 		{
@@ -839,7 +839,7 @@ func TestNativeHistogram(t *testing.T) {
 					{Offset: proto.Int32(0), Length: proto.Uint32(5)},
 				},
 				NegativeDelta:    []int64{1, -1, 2, -2, 2},
-				CreatedTimestamp: timestamppb.New(nowFn()),
+				CreatedTimestamp: timestamppb.New(now),
 			},
 		},
 		{
@@ -857,7 +857,7 @@ func TestNativeHistogram(t *testing.T) {
 					{Offset: proto.Int32(0), Length: proto.Uint32(5)},
 				},
 				NegativeDelta:    []int64{1, 2, -1, -2, 1},
-				CreatedTimestamp: timestamppb.New(nowFn()),
+				CreatedTimestamp: timestamppb.New(now),
 			},
 		},
 		{
@@ -876,7 +876,7 @@ func TestNativeHistogram(t *testing.T) {
 					{Offset: proto.Int32(1), Length: proto.Uint32(7)},
 				},
 				NegativeDelta:    []int64{1, 1, -2, 2, -2, 0, 1},
-				CreatedTimestamp: timestamppb.New(nowFn()),
+				CreatedTimestamp: timestamppb.New(now),
 			},
 		},
 		{
@@ -895,7 +895,7 @@ func TestNativeHistogram(t *testing.T) {
 					{Offset: proto.Int32(2), Length: proto.Uint32(7)},
 				},
 				NegativeDelta:    []int64{2, -2, 2, -2, 0, 1, 0},
-				CreatedTimestamp: timestamppb.New(nowFn()),
+				CreatedTimestamp: timestamppb.New(now),
 			},
 		},
 		{
@@ -915,7 +915,7 @@ func TestNativeHistogram(t *testing.T) {
 					{Offset: proto.Int32(7), Length: proto.Uint32(2)},
 				},
 				NegativeDelta:    []int64{1, 0},
-				CreatedTimestamp: timestamppb.New(nowFn()),
+				CreatedTimestamp: timestamppb.New(now.Add(8 * time.Minute)), // We expect reset to happen after 8 observations.
 			},
 		},
 		{
@@ -934,7 +934,7 @@ func TestNativeHistogram(t *testing.T) {
 					{Offset: proto.Int32(7), Length: proto.Uint32(2)},
 				},
 				PositiveDelta:    []int64{1, 0},
-				CreatedTimestamp: timestamppb.New(nowFn()),
+				CreatedTimestamp: timestamppb.New(now.Add(10 * time.Minute)), // We expect reset to happen after 9 minutes.
 			},
 		},
 		{
@@ -954,13 +954,15 @@ func TestNativeHistogram(t *testing.T) {
 					{Offset: proto.Int32(7), Length: proto.Uint32(2)},
 				},
 				PositiveDelta:    []int64{1, 0},
-				CreatedTimestamp: timestamppb.New(nowFn()),
+				CreatedTimestamp: timestamppb.New(now.Add(10 * time.Minute)), // We expect reset to happen after 9 minutes.
 			},
 		},
 	}
 
 	for _, s := range scenarios {
 		t.Run(s.name, func(t *testing.T) {
+			ts := now
+
 			his := NewHistogram(HistogramOpts{
 				Name:                            "name",
 				Help:                            "help",
@@ -969,13 +971,10 @@ func TestNativeHistogram(t *testing.T) {
 				NativeHistogramMaxBucketNumber:  s.maxBuckets,
 				NativeHistogramMinResetDuration: s.minResetDuration,
 				NativeHistogramMaxZeroThreshold: s.maxZeroThreshold,
-				now:                             nowFn,
+				now:                             func() time.Time { return ts },
 			})
-			ts := time.Now().Add(30 * time.Second)
+
-			now := func() time.Time {
+			ts = ts.Add(time.Minute)
-				return ts
-			}
-			his.(*histogram).now = now
 			for _, o := range s.observations {
 				his.Observe(o)
 				ts = ts.Add(time.Minute)
@@ -1000,6 +999,8 @@ func TestNativeHistogramConcurrency(t *testing.T) {
 	rand.Seed(42)
 
 	it := func(n uint32) bool {
+		ts := time.Now().Add(30 * time.Second).Unix()
+
 		mutations := int(n%1e4 + 1e4)
 		concLevel := int(n%5 + 1)
 		total := mutations * concLevel
@@ -1016,14 +1017,11 @@ func TestNativeHistogramConcurrency(t *testing.T) {
 			NativeHistogramMaxBucketNumber:  50,
 			NativeHistogramMinResetDuration: time.Hour, // Comment out to test for totals below.
 			NativeHistogramMaxZeroThreshold: 0.001,
+			now: func() time.Time {
+				return time.Unix(atomic.LoadInt64(&ts), 0)
+			},
 		})
 
-		ts := time.Now().Add(30 * time.Second).Unix()
-		now := func() time.Time {
-			return time.Unix(atomic.LoadInt64(&ts), 0)
-		}
-		his.(*histogram).now = now
-
 		allVars := make([]float64, total)
 		var sampleSum float64
 		for i := 0; i < concLevel; i++ {
@@ -1221,3 +1219,41 @@ func TestHistogramVecCreatedTimestamp(t *testing.T) {
 		t.Errorf("expected created timestamp %d, got %d", now.Unix(), metric.Histogram.CreatedTimestamp.AsTime().Unix())
 	}
 }
+
+func TestHistogramVecCreatedTimestampWithDeletes(t *testing.T) {
+	now := time.Now()
+
+	histogramVec := NewHistogramVec(HistogramOpts{
+		Name:    "test",
+		Help:    "test help",
+		Buckets: []float64{1, 2, 3, 4},
+		now:     func() time.Time { return now },
+	}, []string{"label"})
+
+	// First use of "With" should populate CT.
+	histogramVec.WithLabelValues("1")
+	expected := map[string]time.Time{"1": now}
+
+	now = now.Add(1 * time.Hour)
+	expectCTsForMetricVecValues(t, histogramVec.MetricVec, dto.MetricType_HISTOGRAM, expected)
+
+	// Two more labels at different times.
+	histogramVec.WithLabelValues("2")
+	expected["2"] = now
+
+	now = now.Add(1 * time.Hour)
+
+	histogramVec.WithLabelValues("3")
+	expected["3"] = now
+
+	now = now.Add(1 * time.Hour)
+	expectCTsForMetricVecValues(t, histogramVec.MetricVec, dto.MetricType_HISTOGRAM, expected)
+
+	// Recreate metric instance should reset created timestamp to now.
+	histogramVec.DeleteLabelValues("1")
+	histogramVec.WithLabelValues("1")
+	expected["1"] = now
+
+	now = now.Add(1 * time.Hour)
+	expectCTsForMetricVecValues(t, histogramVec.MetricVec, dto.MetricType_HISTOGRAM, expected)
+}

prometheus/metric.go

@@ -93,7 +93,8 @@ type Opts struct {
 	// https://prometheus.io/docs/instrumenting/writing_exporters/#target-labels-not-static-scraped-labels
 	ConstLabels Labels
 
-	now func() time.Time // For testing, all constructors put time.Now() here.
+	// now is for testing purposes, by default it's time.Now.
+	now func() time.Time
 }
 
 // BuildFQName joins the given three name components by "_". Empty name

prometheus/summary.go

@@ -147,7 +147,8 @@ type SummaryOpts struct {
 	// "github.com/bmizerany/perks/quantile").
 	BufCap uint32
 
-	now func() time.Time // For testing, all constructors put time.Now() here.
+	// now is for testing purposes, by default it's time.Now.
+	now func() time.Time
 }
 
 // SummaryVecOpts bundles the options to create a SummaryVec metric.
@@ -252,7 +253,7 @@ func newSummary(desc *Desc, opts SummaryOpts, labelValues ...string) Summary {
 		coldBuf:        make([]float64, 0, opts.BufCap),
 		streamDuration: opts.MaxAge / time.Duration(opts.AgeBuckets),
 	}
-	s.headStreamExpTime = time.Now().Add(s.streamDuration)
+	s.headStreamExpTime = opts.now().Add(s.streamDuration)
 	s.hotBufExpTime = s.headStreamExpTime
 
 	for i := uint32(0); i < opts.AgeBuckets; i++ {

prometheus/summary_test.go

@@ -26,10 +26,13 @@ import (
 )
 
 func TestSummaryWithDefaultObjectives(t *testing.T) {
+	now := time.Now()
+
 	reg := NewRegistry()
 	summaryWithDefaultObjectives := NewSummary(SummaryOpts{
 		Name: "default_objectives",
 		Help: "Test help.",
+		now:  func() time.Time { return now },
 	})
 	if err := reg.Register(summaryWithDefaultObjectives); err != nil {
 		t.Error(err)
@@ -42,6 +45,10 @@ func TestSummaryWithDefaultObjectives(t *testing.T) {
 	if len(m.GetSummary().Quantile) != 0 {
 		t.Error("expected no objectives in summary")
 	}
+
+	if !m.Summary.CreatedTimestamp.AsTime().Equal(now) {
+		t.Errorf("expected created timestamp %s, got %s", now, m.Summary.CreatedTimestamp.AsTime())
+	}
 }
 
 func TestSummaryWithoutObjectives(t *testing.T) {
@@ -421,77 +428,49 @@ func getBounds(vars []float64, q, ε float64) (min, max float64) {
 	return
 }
 
-func TestSummaryCreatedTimestamp(t *testing.T) {
+func TestSummaryVecCreatedTimestampWithDeletes(t *testing.T) {
-	testCases := []struct {
+	for _, tcase := range []struct {
 		desc       string
 		objectives map[float64]float64
 	}{
-		{
+		{desc: "summary with objectives", objectives: map[float64]float64{1.0: 1.0}},
-			desc: "summary with objectives",
+		{desc: "no objectives summary", objectives: nil},
-			objectives: map[float64]float64{
+	} {
-				1.0: 1.0,
+		now := time.Now()
-			},
+		t.Run(tcase.desc, func(t *testing.T) {
-		},
-		{
-			desc:       "no objectives summary",
-			objectives: nil,
-		},
-	}
-	now := time.Now()
-	for _, test := range testCases {
-		test := test
-		t.Run(test.desc, func(t *testing.T) {
-			summary := NewSummary(SummaryOpts{
-				Name:       "test",
-				Help:       "test help",
-				Objectives: test.objectives,
-				now:        func() time.Time { return now },
-			})
-
-			var metric dto.Metric
-			summary.Write(&metric)
-
-			if metric.Summary.CreatedTimestamp.AsTime().Unix() != now.Unix() {
-				t.Errorf("expected created timestamp %d, got %d", now.Unix(), metric.Summary.CreatedTimestamp.AsTime().Unix())
-			}
-		})
-	}
-}
-
-func TestSummaryVecCreatedTimestamp(t *testing.T) {
-	testCases := []struct {
-		desc       string
-		objectives map[float64]float64
-	}{
-		{
-			desc: "summary with objectives",
-			objectives: map[float64]float64{
-				1.0: 1.0,
-			},
-		},
-		{
-			desc:       "no objectives summary",
-			objectives: nil,
-		},
-	}
-	now := time.Now()
-	for _, test := range testCases {
-		test := test
-		t.Run(test.desc, func(t *testing.T) {
 			summaryVec := NewSummaryVec(SummaryOpts{
 				Name:       "test",
 				Help:       "test help",
-				Objectives: test.objectives,
+				Objectives: tcase.objectives,
 				now:        func() time.Time { return now },
-			},
+			}, []string{"label"})
-				[]string{"label"})
-			summary := summaryVec.WithLabelValues("value").(Summary)
-			var metric dto.Metric
-			summary.Write(&metric)
 
-			if metric.Summary.CreatedTimestamp.AsTime().Unix() != now.Unix() {
+			// First use of "With" should populate CT.
-				t.Errorf("expected created timestamp %d, got %d", now.Unix(), metric.Summary.CreatedTimestamp.AsTime().Unix())
+			summaryVec.WithLabelValues("1")
-			}
+			expected := map[string]time.Time{"1": now}
+
+			now = now.Add(1 * time.Hour)
+			expectCTsForMetricVecValues(t, summaryVec.MetricVec, dto.MetricType_SUMMARY, expected)
+
+			// Two more labels at different times.
+			summaryVec.WithLabelValues("2")
+			expected["2"] = now
+
+			now = now.Add(1 * time.Hour)
+
+			summaryVec.WithLabelValues("3")
+			expected["3"] = now
+
+			now = now.Add(1 * time.Hour)
+			expectCTsForMetricVecValues(t, summaryVec.MetricVec, dto.MetricType_SUMMARY, expected)
+
+			// Recreate metric instance should reset created timestamp to now.
+			summaryVec.DeleteLabelValues("1")
+			summaryVec.WithLabelValues("1")
+			expected["1"] = now
+
+			now = now.Add(1 * time.Hour)
+			expectCTsForMetricVecValues(t, summaryVec.MetricVec, dto.MetricType_SUMMARY, expected)
 		})
 	}
 }

prometheus/utils_test.go

@@ -15,21 +15,42 @@ package prometheus_test
 import (
 	"bytes"
 	"encoding/json"
-	"fmt"
+	"time"
 
+	dto "github.com/prometheus/client_model/go"
 	"google.golang.org/protobuf/encoding/protojson"
 	"google.golang.org/protobuf/proto"
+	"google.golang.org/protobuf/types/known/timestamppb"
 )
 
-// printlnNormalized is a helper function to compare proto messages in json format.
+// sanitizeMetric injects expected fake created timestamp value "1970-01-01T00:00:10Z",
-// Without removing brittle, we can't assert that two proto messages in json/text format are equal.
+// so we can compare it in examples. It modifies metric in-place, the returned pointer
-// Read more in https://github.com/golang/protobuf/issues/1121
+// is for convenience.
-func printlnNormalized(m proto.Message) {
+func sanitizeMetric(metric *dto.Metric) *dto.Metric {
-	fmt.Println(protoToNormalizedJSON(m))
+	if metric.Counter != nil && metric.Counter.CreatedTimestamp != nil {
+		metric.Counter.CreatedTimestamp = timestamppb.New(time.Unix(10, 0))
+	}
+	if metric.Summary != nil && metric.Summary.CreatedTimestamp != nil {
+		metric.Summary.CreatedTimestamp = timestamppb.New(time.Unix(10, 0))
+	}
+	if metric.Histogram != nil && metric.Histogram.CreatedTimestamp != nil {
+		metric.Histogram.CreatedTimestamp = timestamppb.New(time.Unix(10, 0))
+	}
+	return metric
 }
 
-// protoToNormalizedJSON works as printlnNormalized, but returns the string instead of printing.
+// sanitizeMetricFamily is like sanitizeMetric, but for multiple metrics.
-func protoToNormalizedJSON(m proto.Message) string {
+func sanitizeMetricFamily(f *dto.MetricFamily) *dto.MetricFamily {
+	for _, m := range f.Metric {
+		sanitizeMetric(m)
+	}
+	return f
+}
+
+// toNormalizedJSON removes fake random space from proto JSON original marshaller.
+// It is required, so we can compare proto messages in json format.
+// Read more in https://github.com/golang/protobuf/issues/1121
+func toNormalizedJSON(m proto.Message) string {
 	mAsJSON, err := protojson.Marshal(m)
 	if err != nil {
 		panic(err)

prometheus/value.go

@@ -144,11 +144,11 @@ func NewConstMetricWithCreatedTimestamp(desc *Desc, valueType ValueType, value f
 	case CounterValue:
 		break
 	default:
-		return nil, errors.New("Created timestamps are only supported for counters")
+		return nil, errors.New("created timestamps are only supported for counters")
 	}
 
 	metric := &dto.Metric{}
-	if err := populateMetric(valueType, value, MakeLabelPairs(desc, labelValues), nil, metric, &ct); err != nil {
+	if err := populateMetric(valueType, value, MakeLabelPairs(desc, labelValues), nil, metric, timestamppb.New(ct)); err != nil {
 		return nil, err
 	}
 
@@ -191,15 +191,11 @@ func populateMetric(
 	labelPairs []*dto.LabelPair,
 	e *dto.Exemplar,
 	m *dto.Metric,
-	createdTimestamp *time.Time,
+	ct *timestamppb.Timestamp,
 ) error {
 	m.Label = labelPairs
 	switch t {
 	case CounterValue:
-		var ct *timestamppb.Timestamp
-		if createdTimestamp != nil {
-			ct = timestamppb.New(*createdTimestamp)
-		}
 		m.Counter = &dto.Counter{Value: proto.Float64(v), Exemplar: e, CreatedTimestamp: ct}
 	case GaugeValue:
 		m.Gauge = &dto.Gauge{Value: proto.Float64(v)}

prometheus/value_test.go

@@ -61,7 +61,8 @@ func TestNewConstMetricInvalidLabelValues(t *testing.T) {
 
 func TestNewConstMetricWithCreatedTimestamp(t *testing.T) {
 	now := time.Now()
-	testCases := []struct {
+
+	for _, tcase := range []struct {
 		desc             string
 		metricType       ValueType
 		createdTimestamp time.Time
@@ -82,30 +83,27 @@ func TestNewConstMetricWithCreatedTimestamp(t *testing.T) {
 			expecErr:         false,
 			expectedCt:       timestamppb.New(now),
 		},
-	}
+	} {
-
+		t.Run(tcase.desc, func(t *testing.T) {
-	for _, test := range testCases {
-		test := test
-		t.Run(test.desc, func(t *testing.T) {
 			metricDesc := NewDesc(
 				"sample_value",
 				"sample value",
 				nil,
 				nil,
 			)
-			m, err := NewConstMetricWithCreatedTimestamp(metricDesc, test.metricType, float64(1), test.createdTimestamp)
+			m, err := NewConstMetricWithCreatedTimestamp(metricDesc, tcase.metricType, float64(1), tcase.createdTimestamp)
-			if test.expecErr && err == nil {
+			if tcase.expecErr && err == nil {
-				t.Errorf("Expected error is test %s, got no err", test.desc)
+				t.Errorf("Expected error is test %s, got no err", tcase.desc)
 			}
-			if !test.expecErr && err != nil {
+			if !tcase.expecErr && err != nil {
-				t.Errorf("Didn't expect error in test %s, got %s", test.desc, err.Error())
+				t.Errorf("Didn't expect error in test %s, got %s", tcase.desc, err.Error())
 			}
 
-			if test.expectedCt != nil {
+			if tcase.expectedCt != nil {
 				var metric dto.Metric
 				m.Write(&metric)
-				if metric.Counter.CreatedTimestamp.AsTime() != test.expectedCt.AsTime() {
+				if metric.Counter.CreatedTimestamp.AsTime() != tcase.expectedCt.AsTime() {
-					t.Errorf("Expected timestamp %v, got %v", test.expectedCt, &metric.Counter.CreatedTimestamp)
+					t.Errorf("Expected timestamp %v, got %v", tcase.expectedCt, &metric.Counter.CreatedTimestamp)
 				}
 			}
 		})