package prometheus_test
import (
"io/ioutil"
"math"
"math/rand"
"net/http"
"net/http/httptest"
"regexp"
"strconv"
"strings"
"testing"
stdprometheus "github.com/prometheus/client_golang/prometheus"
"github.com/peterbourgon/gokit/metrics"
"github.com/peterbourgon/gokit/metrics/prometheus"
)
func TestPrometheusLabelBehavior(t *testing.T) {
c := prometheus.NewCounter("test", "prometheus_label_behavior", "foobar", "Abc def.", []string{"used_key", "unused_key"})
c.With(metrics.Field{Key: "used_key", Value: "declared"}).Add(1)
c.Add(1)
if want, have := strings.Join([]string{
`# HELP test_prometheus_label_behavior_foobar Abc def.`,
`# TYPE test_prometheus_label_behavior_foobar counter`,
`test_prometheus_label_behavior_foobar{unused_key="unknown",used_key="declared"} 1`,
`test_prometheus_label_behavior_foobar{unused_key="unknown",used_key="unknown"} 1`,
}, "\n"), scrapePrometheus(t); !strings.Contains(have, want) {
t.Errorf("metric stanza not found or incorrect\n%s", have)
}
}
func TestPrometheusCounter(t *testing.T) {
c := prometheus.NewCounter("test", "prometheus_counter", "foobar", "Lorem ipsum.", []string{})
c.Add(1)
c.Add(2)
if want, have := strings.Join([]string{
`# HELP test_prometheus_counter_foobar Lorem ipsum.`,
`# TYPE test_prometheus_counter_foobar counter`,
`test_prometheus_counter_foobar 3`,
}, "\n"), scrapePrometheus(t); !strings.Contains(have, want) {
t.Errorf("metric stanza not found or incorrect\n%s", have)
}
c.Add(3)
c.Add(4)
if want, have := strings.Join([]string{
`# HELP test_prometheus_counter_foobar Lorem ipsum.`,
`# TYPE test_prometheus_counter_foobar counter`,
`test_prometheus_counter_foobar 10`,
}, "\n"), scrapePrometheus(t); !strings.Contains(have, want) {
t.Errorf("metric stanza not found or incorrect\n%s", have)
}
}
func TestPrometheusGauge(t *testing.T) {
c := prometheus.NewGauge("test", "prometheus_gauge", "foobar", "Dolor sit.", []string{})
c.Set(42)
if want, have := strings.Join([]string{
`# HELP test_prometheus_gauge_foobar Dolor sit.`,
`# TYPE test_prometheus_gauge_foobar gauge`,
`test_prometheus_gauge_foobar 42`,
}, "\n"), scrapePrometheus(t); !strings.Contains(have, want) {
t.Errorf("metric stanza not found or incorrect\n%s", have)
}
c.Add(-43)
if want, have := strings.Join([]string{
`# HELP test_prometheus_gauge_foobar Dolor sit.`,
`# TYPE test_prometheus_gauge_foobar gauge`,
`test_prometheus_gauge_foobar -1`,
}, "\n"), scrapePrometheus(t); !strings.Contains(have, want) {
t.Errorf("metric stanza not found or incorrect\n%s", have)
}
}
func TestPrometheusHistogram(t *testing.T) {
h := prometheus.NewHistogram("test", "prometheus_histogram", "foobar", "Qwerty asdf.", []string{})
const mean, stdev int64 = 50, 10
populateNormalHistogram(t, h, 34, mean, stdev)
assertNormalHistogram(t, "test_prometheus_histogram_foobar", mean, stdev)
}
func populateNormalHistogram(t *testing.T, h metrics.Histogram, seed int64, mean, stdev int64) {
rand.Seed(seed)
for i := 0; i < 1234; i++ {
sample := int64(rand.NormFloat64()*float64(stdev) + float64(mean))
h.Observe(sample)
}
}
func assertNormalHistogram(t *testing.T, metricName string, mean, stdev int64) {
scrape := scrapePrometheus(t)
const tolerance int = 5 // Prometheus approximates higher quantiles badly -_-;
for quantileInt, quantileStr := range map[int]string{50: "0.5", 90: "0.9", 99: "0.99"} {
want := normalValueAtQuantile(mean, stdev, quantileInt)
have := getPrometheusQuantile(t, scrape, metricName, quantileStr)
if int(math.Abs(float64(want)-float64(have))) > tolerance {
t.Errorf("%q: want %d, have %d", quantileStr, want, have)
}
}
}
// https://en.wikipedia.org/wiki/Normal_distribution#Quantile_function
func normalValueAtQuantile(mean, stdev int64, quantile int) int64 {
return int64(float64(mean) + float64(stdev)*math.Sqrt2*erfinv(2*(float64(quantile)/100)-1))
}
// https://stackoverflow.com/questions/5971830/need-code-for-inverse-error-function
func erfinv(y float64) float64 {
if y < -1.0 || y > 1.0 {
panic("invalid input")
}
var (
a = [4]float64{0.886226899, -1.645349621, 0.914624893, -0.140543331}
b = [4]float64{-2.118377725, 1.442710462, -0.329097515, 0.012229801}
c = [4]float64{-1.970840454, -1.624906493, 3.429567803, 1.641345311}
d = [2]float64{3.543889200, 1.637067800}
)
const y0 = 0.7
var x, z float64
if math.Abs(y) == 1.0 {
x = -y * math.Log(0.0)
} else if y < -y0 {
z = math.Sqrt(-math.Log((1.0 + y) / 2.0))
x = -(((c[3]*z+c[2])*z+c[1])*z + c[0]) / ((d[1]*z+d[0])*z + 1.0)
} else {
if y < y0 {
z = y * y
x = y * (((a[3]*z+a[2])*z+a[1])*z + a[0]) / ((((b[3]*z+b[3])*z+b[1])*z+b[0])*z + 1.0)
} else {
z = math.Sqrt(-math.Log((1.0 - y) / 2.0))
x = (((c[3]*z+c[2])*z+c[1])*z + c[0]) / ((d[1]*z+d[0])*z + 1.0)
}
x = x - (math.Erf(x)-y)/(2.0/math.SqrtPi*math.Exp(-x*x))
x = x - (math.Erf(x)-y)/(2.0/math.SqrtPi*math.Exp(-x*x))
}
return x
}
func scrapePrometheus(t *testing.T) string {
server := httptest.NewServer(stdprometheus.UninstrumentedHandler())
defer server.Close()
resp, err := http.Get(server.URL)
if err != nil {
t.Fatal(err)
}
defer resp.Body.Close()
buf, err := ioutil.ReadAll(resp.Body)
if err != nil {
t.Fatal(err)
}
return strings.TrimSpace(string(buf))
}
func getPrometheusQuantile(t *testing.T, scrape, name, quantileStr string) int {
matches := regexp.MustCompile(name+`{quantile="`+quantileStr+`"} ([0-9]+)`).FindAllStringSubmatch(scrape, -1)
if len(matches) < 1 {
t.Fatalf("%q: quantile %q not found in scrape", name, quantileStr)
}
if len(matches[0]) < 2 {
t.Fatalf("%q: quantile %q not found in scrape", name, quantileStr)
}
i, err := strconv.Atoi(matches[0][1])
if err != nil {
t.Fatal(err)
}
return i
}