github.com/prometheus/common v0.55.0

Clean-room public code sample — generation instructions

Write a brand-new, minimal, self-contained code sample in this clean-room directory.
Do not copy, paraphrase, or reference any existing project source. Work only from this spec.

A csx.json manifest scaffold already exists. Do not recreate it from memory. Preserve its case.goal, packages and symbols; fill its empty case.contract with exact assertions and correct its environment, commands and verifierAdapter for the files you generate.

Goal: verify pkg:golang/github.com/prometheus/common@v0.55.0
Kind: HOW

Use EXACTLY these public packages and versions:
  - pkg:golang/github.com/prometheus/common@v0.55.0

Rules:
  - One focused purpose; the smallest project that proves the goal.
  - Include a contract test (test/contract.*) that runs OFFLINE and exits 0 exactly when the goal behavior works.
  - Pin every dependency with a lockfile so resolution is reproducible.
  - No secrets, credentials, or tokens. No real URLs (only example.com or localhost). No absolute paths.
  - No personal names, emails, company names, or project identifiers of any kind.
  - No binaries and no generated output (node_modules, dist, target, venv, .git, .env).
  - Keep it under 200 files and 256KB packed.

{"case":{"caseId":"case:sha256:f0fd27c36274dc21e1646a2d72c439ce7acd820ee3276c6a71283af7a595f5ec","contract":["model.ParseDuration parses compound Prometheus duration strings into model.Duration and rejects invalid duration syntax","model.IsValidMetricName and model.LabelName.IsValid validate Prometheus metric and label naming rules","model.Metric.Fingerprint and FastFingerprint compute deterministic hashes and format LabelSet string representations independent of map insertion order","expfmt.TextParser.TextToMetricFamilies and expfmt.ExtractSamples parse Prometheus text exposition into a model.Vector with labels, values, and timestamps","expfmt.MetricFamilyToText serializes a MetricFamily back into Prometheus text format"],"goal":"verify pkg:golang/github.com/prometheus/common@v0.55.0","kind":"HOW","packages":["pkg:golang/github.com/prometheus/common@v0.55.0"],"schemaVersion":1},"contractCommand":["go","run","./test"],"environment":{"arch":"x64","distro":"ubuntu","ecosystem":"golang","libc":"glibc","libcVersion":"2.39","os":"linux","osVersionBucket":"24","packageManager":"go","schemaVersion":1},"license":"MIT-0","packages":["pkg:golang/github.com/prometheus/common@v0.55.0"],"schemaVersion":1,"subject":"pkg:golang/github.com/prometheus/common@v0.55.0","verifierAdapter":"golang@1"}

module sample

go 1.22

require github.com/prometheus/common v0.55.0

require (
	github.com/munnerz/goautoneg v0.0.0-20191010083416-a7dc8b61c822 // indirect
	github.com/prometheus/client_model v0.6.1 // indirect
	google.golang.org/protobuf v1.34.2 // indirect
)

github.com/google/go-cmp v0.6.0 h1:ofyhxvXcZhMsU5ulbFiLKl/XBFqE1GSq7atu8tAmTRI=
github.com/google/go-cmp v0.6.0/go.mod h1:17dUlkBOakJ0+DkrSSNjCkIjxS6bF9zb3elmeNGIjoY=
github.com/munnerz/goautoneg v0.0.0-20191010083416-a7dc8b61c822 h1:C3w9PqII01/Oq1c1nUAm88MOHcQC9l5mIlSMApZMrHA=
github.com/munnerz/goautoneg v0.0.0-20191010083416-a7dc8b61c822/go.mod h1:+n7T8mK8HuQTcFwEeznm/DIxMOiR9yIdICNftLE1DvQ=
github.com/prometheus/client_model v0.6.1 h1:ZKSh/rekM+n3CeS952MLRAdFwIKqeY8b62p8ais2e9E=
github.com/prometheus/client_model v0.6.1/go.mod h1:OrxVMOVHjw3lKMa8+x6HeMGkHMQyHDk9E3jmP2AmGiY=
github.com/prometheus/common v0.55.0 h1:KEi6DK7lXW/m7Ig5i47x0vRzuBsHuvJdi5ee6Y3G1dc=
github.com/prometheus/common v0.55.0/go.mod h1:2SECS4xJG1kd8XF9IcM1gMX6510RAEL65zxzNImwdc8=
google.golang.org/protobuf v1.34.2 h1:6xV6lTsCfpGD21XK49h7MhtcApnLqkfYgPcdHftf6hg=
google.golang.org/protobuf v1.34.2/go.mod h1:qYOHts0dSfpeUzUFpOMr/WGzszTmLH+DiWniOlNbLDw=

{
  "schemaVersion": 1,
  "goal": "verify pkg:golang/github.com/prometheus/common@v0.55.0",
  "kind": "HOW",
  "packages": [
    "pkg:golang/github.com/prometheus/common@v0.55.0"
  ]
}

package main

import (
	"fmt"
	"os"
	"strings"
	"time"

	"github.com/prometheus/common/expfmt"
	"github.com/prometheus/common/model"
)

func fail(msg string) {
	fmt.Fprintln(os.Stderr, "FAIL:", msg)
	os.Exit(1)
}

func main() {
	// 1. model.ParseDuration parses compound Prometheus duration strings into model.Duration
	d, err := model.ParseDuration("1h30m")
	if err != nil {
		fail(fmt.Sprintf("ParseDuration failed: %v", err))
	}
	if time.Duration(d) != 90*time.Minute || d.String() != "1h30m" {
		fail(fmt.Sprintf("unexpected duration: %v (%s)", time.Duration(d), d.String()))
	}
	if _, err := model.ParseDuration("invalid"); err == nil {
		fail("expected error for invalid duration string")
	}

	// 2. model.IsValidMetricName and model.LabelName.IsValid validate Prometheus metric and label names
	if !model.IsValidMetricName("http_requests_total:rate5m") {
		fail("expected valid metric name")
	}
	if model.IsValidMetricName("9invalid_metric") {
		fail("expected invalid metric name starting with digit")
	}
	if !model.LabelName("status_code").IsValid() {
		fail("expected valid label name")
	}
	if model.LabelName("status-code").IsValid() {
		fail("expected invalid label name containing hyphen")
	}

	// 3. model.Metric.Fingerprint and FastFingerprint compute deterministic hashes and format as LabelSet strings
	m1 := model.Metric{
		model.MetricNameLabel: "http_requests_total",
		"method":              "GET",
		"code":                "200",
	}
	m2 := model.Metric{
		"code":                "200",
		"method":              "GET",
		model.MetricNameLabel: "http_requests_total",
	}
	if m1.Fingerprint() != m2.Fingerprint() || m1.FastFingerprint() != m2.FastFingerprint() {
		fail("expected identical fingerprints for equal metrics regardless of construction order")
	}
	if m1.String() != `http_requests_total{code="200", method="GET"}` {
		fail(fmt.Sprintf("unexpected metric string: %s", m1.String()))
	}

	// 4. expfmt.TextParser.TextToMetricFamilies and expfmt.ExtractSamples parse text exposition into a model.Vector
	exposition := `# HELP http_requests_total Total HTTP requests.
# TYPE http_requests_total counter
http_requests_total{method="GET",code="200"} 42 1700000000000
http_requests_total{method="POST",code="201"} 7 1700000005000
`
	var parser expfmt.TextParser
	fams, err := parser.TextToMetricFamilies(strings.NewReader(exposition))
	if err != nil {
		fail(fmt.Sprintf("TextToMetricFamilies failed: %v", err))
	}
	fam, ok := fams["http_requests_total"]
	if !ok || len(fam.GetMetric()) != 2 {
		fail("expected http_requests_total family with 2 metrics")
	}

	vec, err := expfmt.ExtractSamples(&expfmt.DecodeOptions{Timestamp: model.Time(1700000000000)}, fam)
	if err != nil {
		fail(fmt.Sprintf("ExtractSamples failed: %v", err))
	}
	if len(vec) != 2 {
		fail(fmt.Sprintf("expected 2 extracted samples, got %d", len(vec)))
	}

	var gotGet, gotPost bool
	for _, s := range vec {
		switch string(s.Metric["method"]) {
		case "GET":
			gotGet = s.Value == 42 && s.Timestamp == model.Time(1700000000000)
		case "POST":
			gotPost = s.Value == 7 && s.Timestamp == model.Time(1700000005000)
		}
	}
	if !gotGet || !gotPost {
		fail(fmt.Sprintf("unexpected sample values in vector: %+v", vec))
	}

	// 5. expfmt.MetricFamilyToText serializes a MetricFamily back into Prometheus text format
	var buf strings.Builder
	written, err := expfmt.MetricFamilyToText(&buf, fam)
	if err != nil || written == 0 {
		fail(fmt.Sprintf("MetricFamilyToText failed: written=%d err=%v", written, err))
	}
	out := buf.String()
	if !strings.Contains(out, "# TYPE http_requests_total counter") || !strings.Contains(out, `http_requests_total{method="GET",code="200"} 42 1700000000000`) {
		fail(fmt.Sprintf("unexpected serialized text output: %s", out))
	}
}