Moved to google.golang.org/genproto/googleapis/api/annotations

Fixes #52

vendor/github.com/go-kit/kit/metrics/teststat/teststat.go

@@ -0,0 +1,114 @@
+// Package teststat provides helpers for testing metrics backends.
+package teststat
+
+import (
+	"errors"
+	"fmt"
+	"math"
+	"math/rand"
+	"strings"
+
+	"github.com/go-kit/kit/metrics"
+)
+
+// TestCounter puts some deltas through the counter, and then calls the value
+// func to check that the counter has the correct final value.
+func TestCounter(counter metrics.Counter, value func() float64) error {
+	a := rand.Perm(100)
+	n := rand.Intn(len(a))
+
+	var want float64
+	for i := 0; i < n; i++ {
+		f := float64(a[i])
+		counter.Add(f)
+		want += f
+	}
+
+	if have := value(); want != have {
+		return fmt.Errorf("want %f, have %f", want, have)
+	}
+
+	return nil
+}
+
+// TestGauge puts some values through the gauge, and then calls the value func
+// to check that the gauge has the correct final value.
+func TestGauge(gauge metrics.Gauge, value func() float64) error {
+	a := rand.Perm(100)
+	n := rand.Intn(len(a))
+
+	var want float64
+	for i := 0; i < n; i++ {
+		f := float64(a[i])
+		gauge.Set(f)
+		want = f
+	}
+
+	for i := 0; i < n; i++ {
+		f := float64(a[i])
+		gauge.Add(f)
+		want += f
+	}
+
+	if have := value(); want != have {
+		return fmt.Errorf("want %f, have %f", want, have)
+	}
+
+	return nil
+}
+
+// TestHistogram puts some observations through the histogram, and then calls
+// the quantiles func to checks that the histogram has computed the correct
+// quantiles within some tolerance
+func TestHistogram(histogram metrics.Histogram, quantiles func() (p50, p90, p95, p99 float64), tolerance float64) error {
+	PopulateNormalHistogram(histogram, rand.Int())
+
+	want50, want90, want95, want99 := normalQuantiles()
+	have50, have90, have95, have99 := quantiles()
+
+	var errs []string
+	if want, have := want50, have50; !cmp(want, have, tolerance) {
+		errs = append(errs, fmt.Sprintf("p50: want %f, have %f", want, have))
+	}
+	if want, have := want90, have90; !cmp(want, have, tolerance) {
+		errs = append(errs, fmt.Sprintf("p90: want %f, have %f", want, have))
+	}
+	if want, have := want95, have95; !cmp(want, have, tolerance) {
+		errs = append(errs, fmt.Sprintf("p95: want %f, have %f", want, have))
+	}
+	if want, have := want99, have99; !cmp(want, have, tolerance) {
+		errs = append(errs, fmt.Sprintf("p99: want %f, have %f", want, have))
+	}
+	if len(errs) > 0 {
+		return errors.New(strings.Join(errs, "; "))
+	}
+
+	return nil
+}
+
+var (
+	// Count is the number of observations.
+	Count = 12345
+
+	// Mean is the center of the normal distribution of observations.
+	Mean = 500
+
+	// Stdev of the normal distribution of observations.
+	Stdev = 25
+)
+
+// ExpectedObservationsLessThan returns the number of observations that should
+// have a value less than or equal to the given value, given a normal
+// distribution of observations described by Count, Mean, and Stdev.
+func ExpectedObservationsLessThan(bucket int64) int64 {
+	// https://code.google.com/p/gostat/source/browse/stat/normal.go
+	cdf := ((1.0 / 2.0) * (1 + math.Erf((float64(bucket)-float64(Mean))/(float64(Stdev)*math.Sqrt2))))
+	return int64(cdf * float64(Count))
+}
+
+func cmp(want, have, tol float64) bool {
+	if (math.Abs(want-have) / want) > tol {
+		return false
+	}
+	return true
+}