github.com/prometheus/client_model v0.6.1: go.LabelPair

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 github.com/prometheus/client_model/go.LabelPair in pkg:golang/github.com/prometheus/client_model@v0.6.1
Kind: HOW

Use EXACTLY these public packages and versions:
  - pkg:golang/github.com/prometheus/client_model@v0.6.1
Demonstrate these symbols/APIs:
  - github.com/prometheus/client_model/go.LabelPair
Constraints:
  - executionContext: node
Required runtime conditions:
  - ecosystem: npm
  - language: javascript
  - moduleSystem: cjs
  - packageManager: npm@10.9.8
  - runtime: node@22.23.2

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:fd6b8bcbac3ef75514f2a37fc9e509d11a71ef907cf5d9a922eee62a65fbffa3","contract":["dto.LabelPair.GetName and dto.LabelPair.GetValue return empty strings on a nil or empty LabelPair, and return configured string values when set.","dto.LabelPair can be instantiated with name and value pointers, serialized and deserialized via google.golang.org/protobuf/proto preserving label fields.","dto.LabelPair.Reset clears all fields of the LabelPair struct.","dto.LabelPair can be used in Prometheus metrics label collections."],"goal":"verify github.com/prometheus/client_model/go.LabelPair in pkg:golang/github.com/prometheus/client_model@v0.6.1","kind":"HOW","packages":["pkg:golang/github.com/prometheus/client_model@v0.6.1"],"schemaVersion":1,"symbols":["github.com/prometheus/client_model/go.LabelPair"]},"contractCommand":["go","test","./..."],"environment":{"arch":"x64","distro":"ubuntu","ecosystem":"golang","executionContext":"go","language":"go","libc":"glibc","libcVersion":"2.39","os":"linux","osVersionBucket":"24","packageManager":"go","runtime":"go","schemaVersion":1},"license":"MIT-0","packages":["pkg:golang/github.com/prometheus/client_model@v0.6.1"],"schemaVersion":1,"subject":"pkg:golang/github.com/prometheus/client_model@v0.6.1","symbols":["github.com/prometheus/client_model/go.LabelPair"],"verifierAdapter":"golang@1"}

module example.com/labelpair

go 1.26.6

require (
	github.com/prometheus/client_model v0.6.1
	google.golang.org/protobuf v1.34.2
)

github.com/google/go-cmp v0.5.5 h1:Khx7svrCpmxxtHBq5j2mp/xVjsi8hQMfNLvJFAlrGgU=
github.com/google/go-cmp v0.5.5/go.mod h1:v8dTdLbMG2kIc/vJvl+f65V22dbkXbowE6jgT/gNBxE=
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=
golang.org/x/xerrors v0.0.0-20191204190536-9bdfabe68543 h1:E7g+9GITq07hpfrRu66IVDexMakfv52eLZ2CXBWiKr4=
golang.org/x/xerrors v0.0.0-20191204190536-9bdfabe68543/go.mod h1:I/5z698sn9Ka8TeJc9MKroUUfqBBauWjQqLJ2OPfmY0=
google.golang.org/protobuf v1.34.2 h1:6xV6lTsCfpGD21XK49h7MhtcApnLqkfYgPcdHftf6hg=
google.golang.org/protobuf v1.34.2/go.mod h1:qYOHts0dSfpeUzUFpOMr/WGzszTmLH+DiWniOlNbLDw=

package main

import (
	"fmt"

	dto "github.com/prometheus/client_model/go"
	"google.golang.org/protobuf/proto"
)

func main() {
	lp := &dto.LabelPair{
		Name:  proto.String("environment"),
		Value: proto.String("production"),
	}

	fmt.Printf("Label: %s=%s\n", lp.GetName(), lp.GetValue())

	data, err := proto.Marshal(lp)
	if err != nil {
		panic(err)
	}

	decoded := &dto.LabelPair{}
	if err := proto.Unmarshal(data, decoded); err != nil {
		panic(err)
	}

	fmt.Printf("Decoded: %s=%s\n", decoded.GetName(), decoded.GetValue())
	lp.Reset()
	fmt.Printf("After Reset: %s=%s\n", lp.GetName(), lp.GetValue())
}

{
  "schemaVersion": 1,
  "goal": "verify github.com/prometheus/client_model/go.LabelPair in pkg:golang/github.com/prometheus/client_model@v0.6.1",
  "kind": "HOW",
  "packages": [
    "pkg:golang/github.com/prometheus/client_model@v0.6.1"
  ],
  "symbols": [
    "github.com/prometheus/client_model/go.LabelPair"
  ],
  "constraints": {
    "executionContext": "node"
  },
  "runtimeConditions": {
    "ecosystem": "npm",
    "language": "javascript",
    "moduleSystem": "cjs",
    "packageManager": "npm@10.9.8",
    "runtime": "node@22.23.2"
  }
}

package test

import (
	"testing"

	dto "github.com/prometheus/client_model/go"
	"google.golang.org/protobuf/proto"
)

func TestLabelPairGetters(t *testing.T) {
	// Nil LabelPair safe getters
	var nilLP *dto.LabelPair
	if got := nilLP.GetName(); got != "" {
		t.Errorf("nilLP.GetName() = %q, want \"\"", got)
	}
	if got := nilLP.GetValue(); got != "" {
		t.Errorf("nilLP.GetValue() = %q, want \"\"", got)
	}

	// Empty LabelPair safe getters
	emptyLP := &dto.LabelPair{}
	if got := emptyLP.GetName(); got != "" {
		t.Errorf("emptyLP.GetName() = %q, want \"\"", got)
	}
	if got := emptyLP.GetValue(); got != "" {
		t.Errorf("emptyLP.GetValue() = %q, want \"\"", got)
	}

	// Configured LabelPair getters
	name := "service_name"
	val := "order_processor"
	lp := &dto.LabelPair{
		Name:  proto.String(name),
		Value: proto.String(val),
	}
	if got := lp.GetName(); got != name {
		t.Errorf("lp.GetName() = %q, want %q", got, name)
	}
	if got := lp.GetValue(); got != val {
		t.Errorf("lp.GetValue() = %q, want %q", got, val)
	}
}

func TestLabelPairProtobufSerialization(t *testing.T) {
	name := "http_method"
	val := "POST"
	original := &dto.LabelPair{
		Name:  proto.String(name),
		Value: proto.String(val),
	}

	data, err := proto.Marshal(original)
	if err != nil {
		t.Fatalf("proto.Marshal failed: %v", err)
	}

	decoded := &dto.LabelPair{}
	if err := proto.Unmarshal(data, decoded); err != nil {
		t.Fatalf("proto.Unmarshal failed: %v", err)
	}

	if decoded.GetName() != name {
		t.Errorf("decoded.GetName() = %q, want %q", decoded.GetName(), name)
	}
	if decoded.GetValue() != val {
		t.Errorf("decoded.GetValue() = %q, want %q", decoded.GetValue(), val)
	}
	if !proto.Equal(original, decoded) {
		t.Error("proto.Equal(original, decoded) = false, want true")
	}
}

func TestLabelPairReset(t *testing.T) {
	lp := &dto.LabelPair{
		Name:  proto.String("region"),
		Value: proto.String("us-west-2"),
	}

	lp.Reset()

	if got := lp.GetName(); got != "" {
		t.Errorf("after Reset(), lp.GetName() = %q, want \"\"", got)
	}
	if got := lp.GetValue(); got != "" {
		t.Errorf("after Reset(), lp.GetValue() = %q, want \"\"", got)
	}
}

func TestLabelPairInMetric(t *testing.T) {
	metric := &dto.Metric{
		Label: []*dto.LabelPair{
			{
				Name:  proto.String("instance"),
				Value: proto.String("web-01"),
			},
			{
				Name:  proto.String("job"),
				Value: proto.String("api"),
			},
		},
		Counter: &dto.Counter{
			Value: proto.Float64(128.0),
		},
	}

	labels := metric.GetLabel()
	if len(labels) != 2 {
		t.Fatalf("len(metric.GetLabel()) = %d, want 2", len(labels))
	}
	if labels[0].GetName() != "instance" || labels[0].GetValue() != "web-01" {
		t.Errorf("label[0] = %s=%s, want instance=web-01", labels[0].GetName(), labels[0].GetValue())
	}
	if labels[1].GetName() != "job" || labels[1].GetValue() != "api" {
		t.Errorf("label[1] = %s=%s, want job=api", labels[1].GetName(), labels[1].GetValue())
	}
}