Add tests for examplars

Signed-off-by: beorn7 <beorn@grafana.com>

prometheus/counter.go

@@ -70,7 +70,7 @@ func NewCounter(opts CounterOpts) Counter {
 		nil,
 		opts.ConstLabels,
 	)
-	result := &counter{desc: desc, labelPairs: desc.constLabelPairs}
+	result := &counter{desc: desc, labelPairs: desc.constLabelPairs, now: time.Now}
 	result.init(result) // Init self-collection.
 	return result
 }
@@ -88,6 +88,8 @@ type counter struct {
 
 	labelPairs []*dto.LabelPair
 	exemplar   atomic.Value // Containing nil or a *dto.Exemplar.
+
+	now func() time.Time // To mock out time.Now() for testing.
 }
 
 func (c *counter) Desc() *Desc {
@@ -140,7 +142,7 @@ func (c *counter) updateExemplar(v float64, l Labels) {
 	if l == nil {
 		return
 	}
-	e, err := newExemplar(v, time.Now(), l)
+	e, err := newExemplar(v, c.now(), l)
 	if err != nil {
 		panic(err)
 	}

prometheus/counter_test.go

@@ -17,6 +17,10 @@ import (
 	"fmt"
 	"math"
 	"testing"
+	"time"
+
+	"github.com/golang/protobuf/proto"
+	"github.com/golang/protobuf/ptypes"
 
 	dto "github.com/prometheus/client_model/go"
 )
@@ -210,3 +214,61 @@ func TestCounterAddSmall(t *testing.T) {
 		t.Errorf("expected %q, got %q", expected, got)
 	}
 }
+
+func TestCounterExemplar(t *testing.T) {
+	now := time.Now()
+
+	counter := NewCounter(CounterOpts{
+		Name: "test",
+		Help: "test help",
+	}).(*counter)
+	counter.now = func() time.Time { return now }
+
+	ts, err := ptypes.TimestampProto(now)
+	if err != nil {
+		t.Fatal(err)
+	}
+	expectedExemplar := &dto.Exemplar{
+		Label: []*dto.LabelPair{
+			&dto.LabelPair{Name: proto.String("foo"), Value: proto.String("bar")},
+		},
+		Value:     proto.Float64(42),
+		Timestamp: ts,
+	}
+
+	counter.AddWithExemplar(42, Labels{"foo": "bar"})
+	if expected, got := expectedExemplar.String(), counter.exemplar.Load().(*dto.Exemplar).String(); expected != got {
+		t.Errorf("expected exemplar %s, got %s.", expected, got)
+	}
+
+	addExemplarWithInvalidLabel := func() (err error) {
+		defer func() {
+			if e := recover(); e != nil {
+				err = e.(error)
+			}
+		}()
+		// Should panic because of invalid label name.
+		counter.AddWithExemplar(42, Labels{":o)": "smile"})
+		return nil
+	}
+	if addExemplarWithInvalidLabel() == nil {
+		t.Error("adding exemplar with invalid label succeeded")
+	}
+
+	addExemplarWithOversizedLabels := func() (err error) {
+		defer func() {
+			if e := recover(); e != nil {
+				err = e.(error)
+			}
+		}()
+		// Should panic because of 65 runes.
+		counter.AddWithExemplar(42, Labels{
+			"abcdefghijklmnopqrstuvwxyz": "26+16 characters",
+			"x1234567":                   "8+15 characters",
+		})
+		return nil
+	}
+	if addExemplarWithOversizedLabels() == nil {
+		t.Error("adding exemplar with oversized labels succeeded")
+	}
+}

prometheus/histogram.go

@@ -198,6 +198,7 @@ func newHistogram(desc *Desc, opts HistogramOpts, labelValues ...string) Histogr
 		upperBounds: opts.Buckets,
 		labelPairs:  makeLabelPairs(desc, labelValues),
 		counts:      [2]*histogramCounts{{}, {}},
+		now:         time.Now,
 	}
 	for i, upperBound := range h.upperBounds {
 		if i < len(h.upperBounds)-1 {
@@ -266,6 +267,8 @@ type histogram struct {
 	upperBounds []float64
 	labelPairs  []*dto.LabelPair
 	exemplars   []atomic.Value // One more than buckets (to include +Inf), each a *dto.Exemplar.
+
+	now func() time.Time // To mock out time.Now() for testing.
 }
 
 func (h *histogram) Desc() *Desc {
@@ -397,7 +400,7 @@ func (h *histogram) updateExemplar(v float64, bucket int, l Labels) {
 	if l == nil {
 		return
 	}
-	e, err := newExemplar(v, time.Now(), l)
+	e, err := newExemplar(v, h.now(), l)
 	if err != nil {
 		panic(err)
 	}

prometheus/histogram_test.go

@@ -22,6 +22,10 @@ import (
 	"sync"
 	"testing"
 	"testing/quick"
+	"time"
+
+	"github.com/golang/protobuf/proto"
+	"github.com/golang/protobuf/ptypes"
 
 	dto "github.com/prometheus/client_model/go"
 )
@@ -182,7 +186,11 @@ func TestHistogramConcurrency(t *testing.T) {
 			go func(vals []float64) {
 				start.Wait()
 				for _, v := range vals {
+					if n%2 == 0 {
 						sum.Observe(v)
+					} else {
+						sum.ObserveWithExemplar(v, Labels{"foo": "bar"})
+					}
 				}
 				end.Done()
 			}(vals)
@@ -201,9 +209,13 @@ func TestHistogramConcurrency(t *testing.T) {
 		}
 
 		wantCounts := getCumulativeCounts(allVars)
+		wantBuckets := len(testBuckets)
+		if !math.IsInf(m.Histogram.Bucket[len(m.Histogram.Bucket)-1].GetUpperBound(), +1) {
+			wantBuckets--
+		}
 
-		if got, want := len(m.Histogram.Bucket), len(testBuckets)-1; got != want {
-			t.Errorf("got %d buckets in protobuf, want %d", got, want)
+		if got := len(m.Histogram.Bucket); got != wantBuckets {
+			t.Errorf("got %d buckets in protobuf, want %d", got, wantBuckets)
 		}
 		for i, wantBound := range testBuckets {
 			if i == len(testBuckets)-1 {
@@ -384,3 +396,62 @@ func TestHistogramAtomicObserve(t *testing.T) {
 		runtime.Gosched()
 	}
 }
+
+func TestHistogramExemplar(t *testing.T) {
+	now := time.Now()
+
+	histogram := NewHistogram(HistogramOpts{
+		Name:    "test",
+		Help:    "test help",
+		Buckets: []float64{1, 2, 3, 4},
+	}).(*histogram)
+	histogram.now = func() time.Time { return now }
+
+	ts, err := ptypes.TimestampProto(now)
+	if err != nil {
+		t.Fatal(err)
+	}
+	expectedExemplars := []*dto.Exemplar{
+		nil,
+		&dto.Exemplar{
+			Label: []*dto.LabelPair{
+				&dto.LabelPair{Name: proto.String("id"), Value: proto.String("2")},
+			},
+			Value:     proto.Float64(1.6),
+			Timestamp: ts,
+		},
+		nil,
+		&dto.Exemplar{
+			Label: []*dto.LabelPair{
+				&dto.LabelPair{Name: proto.String("id"), Value: proto.String("3")},
+			},
+			Value:     proto.Float64(4),
+			Timestamp: ts,
+		},
+		&dto.Exemplar{
+			Label: []*dto.LabelPair{
+				&dto.LabelPair{Name: proto.String("id"), Value: proto.String("4")},
+			},
+			Value:     proto.Float64(4.5),
+			Timestamp: ts,
+		},
+	}
+
+	histogram.ObserveWithExemplar(1.5, Labels{"id": "1"})
+	histogram.ObserveWithExemplar(1.6, Labels{"id": "2"}) // To replace exemplar in bucket 0.
+	histogram.ObserveWithExemplar(4, Labels{"id": "3"})
+	histogram.ObserveWithExemplar(4.5, Labels{"id": "4"}) // Should go to +Inf bucket.
+
+	for i, ex := range histogram.exemplars {
+		var got, expected string
+		if val := ex.Load(); val != nil {
+			got = val.(*dto.Exemplar).String()
+		}
+		if expectedExemplars[i] != nil {
+			expected = expectedExemplars[i].String()
+		}
+		if got != expected {
+			t.Errorf("expected exemplar %s, got %s.", expected, got)
+		}
+	}
+}