Function TestHistogramExemplar

prometheus/histogram_test.go:413–470

(t *testing.T)

}

func TestHistogramExemplar(t *testing.T) {
	now := time.Now()

	histogram := NewHistogram(HistogramOpts{
		Name:    "test",
		Help:    "test help",
		Buckets: []float64{1, 2, 3, 4},
		now:     func() time.Time { return now },
	}).(*histogram)

	ts := timestamppb.New(now)
	if err := ts.CheckValid(); err != nil {
		t.Fatal(err)
	}
	expectedExemplars := []*dto.Exemplar{
		nil,
		{
			Label: []*dto.LabelPair{
				{Name: proto.String("id"), Value: proto.String("2")},
			},
			Value:     proto.Float64(1.6),
			Timestamp: ts,
		},
		nil,
		{
			Label: []*dto.LabelPair{
				{Name: proto.String("id"), Value: proto.String("3")},
			},
			Value:     proto.Float64(4),
			Timestamp: ts,
		},
		{
			Label: []*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)
		}
	}
}