github.com/prometheus/client_model v0.0.0-20190812154241-14fe0d1b01d4: go.MetricFamily

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.MetricFamily in pkg:golang/github.com/prometheus/client_model@v0.0.0-20190812154241-14fe0d1b01d4
Kind: HOW

Use EXACTLY these public packages and versions:
  - pkg:golang/github.com/prometheus/client_model@v0.0.0-20190812154241-14fe0d1b01d4
Demonstrate these symbols/APIs:
  - github.com/prometheus/client_model/go.MetricFamily

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.

package sample

import (
	"testing"

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

func TestMetricFamilyGettersAndNilSafety(t *testing.T) {
	var nilMF *dto.MetricFamily

	// Assert safe nil receiver access returns default zero values
	if nilMF.GetName() != "" {
		t.Errorf("expected empty string for nil GetName, got %q", nilMF.GetName())
	}
	if nilMF.GetHelp() != "" {
		t.Errorf("expected empty string for nil GetHelp, got %q", nilMF.GetHelp())
	}
	if nilMF.GetType() != dto.MetricType_COUNTER {
		t.Errorf("expected default MetricType_COUNTER for nil GetType, got %v", nilMF.GetType())
	}
	if nilMF.GetMetric() != nil {
		t.Errorf("expected nil slice for nil GetMetric, got %v", nilMF.GetMetric())
	}

	// Assert unpopulated struct returns default zero values
	emptyMF := &dto.MetricFamily{}
	if emptyMF.GetName() != "" {
		t.Errorf("expected empty string for empty GetName, got %q", emptyMF.GetName())
	}
	if emptyMF.GetHelp() != "" {
		t.Errorf("expected empty string for empty GetHelp, got %q", emptyMF.GetHelp())
	}
	if emptyMF.GetType() != dto.MetricType_COUNTER {
		t.Errorf("expected default MetricType_COUNTER for empty GetType, got %v", emptyMF.GetType())
	}
	if emptyMF.GetMetric() != nil {
		t.Errorf("expected nil slice for empty GetMetric, got %v", emptyMF.GetMetric())
	}

	// Assert populated struct getters return assigned values
	name := "http_requests_total"
	help := "Total number of HTTP requests processed"
	mf := &dto.MetricFamily{
		Name: proto.String(name),
		Help: proto.String(help),
		Type: dto.MetricType_COUNTER.Enum(),
	}

	if mf.GetName() != name {
		t.Errorf("expected GetName() = %q, got %q", name, mf.GetName())
	}
	if mf.GetHelp() != help {
		t.Errorf("expected GetHelp() = %q, got %q", help, mf.GetHelp())
	}
	if mf.GetType() != dto.MetricType_COUNTER {
		t.Errorf("expected GetType() = %v, got %v", dto.MetricType_COUNTER, mf.GetType())
	}
}

func TestBuildCounterMetricFamily(t *testing.T) {
	labels := map[string]string{
		"method": "GET",
		"status": "200",
	}
	mf := BuildCounterMetricFamily(
		"http_requests_total",
		"Total number of HTTP requests processed",
		labels,
		1024.0,
	)

	if mf.GetName() != "http_requests_total" {
		t.Fatalf("expected name http_requests_total, got %s", mf.GetName())
	}
	if mf.GetHelp() != "Total number of HTTP requests processed" {
		t.Fatalf("expected help match, got %s", mf.GetHelp())
	}
	if mf.GetType() != dto.MetricType_COUNTER {
		t.Fatalf("expected type COUNTER, got %v", mf.GetType())
	}
	if len(mf.GetMetric()) != 1 {
		t.Fatalf("expected 1 metric, got %d", len(mf.GetMetric()))
	}

	m := mf.GetMetric()[0]
	if m.GetCounter() == nil {
		t.Fatalf("expected counter to be present")
	}
	if m.GetCounter().GetValue() != 1024.0 {
		t.Fatalf("expected counter value 1024.0, got %f", m.GetCounter().GetValue())
	}
	if len(m.GetLabel()) != 2 {
		t.Fatalf("expected 2 labels, got %d", len(m.GetLabel()))
	}
	if m.GetLabel()[0].GetName() != "method" || m.GetLabel()[0].GetValue() != "GET" {
		t.Errorf("unexpected first label: %v", m.GetLabel()[0])
	}
	if m.GetLabel()[1].GetName() != "status" || m.GetLabel()[1].GetValue() != "200" {
		t.Errorf("unexpected second label: %v", m.GetLabel()[1])
	}
}

func TestBuildGaugeMetricFamily(t *testing.T) {
	labels := map[string]string{
		"instance": "localhost:9090",
	}
	mf := BuildGaugeMetricFamily(
		"memory_usage_bytes",
		"Current memory usage in bytes",
		labels,
		67108864.0,
	)

	if mf.GetName() != "memory_usage_bytes" {
		t.Fatalf("expected name memory_usage_bytes, got %s", mf.GetName())
	}
	if mf.GetHelp() != "Current memory usage in bytes" {
		t.Fatalf("expected help match, got %s", mf.GetHelp())
	}
	if mf.GetType() != dto.MetricType_GAUGE {
		t.Fatalf("expected type GAUGE, got %v", mf.GetType())
	}
	if len(mf.GetMetric()) != 1 {
		t.Fatalf("expected 1 metric, got %d", len(mf.GetMetric()))
	}

	m := mf.GetMetric()[0]
	if m.GetGauge() == nil {
		t.Fatalf("expected gauge to be present")
	}
	if m.GetGauge().GetValue() != 67108864.0 {
		t.Fatalf("expected gauge value 67108864.0, got %f", m.GetGauge().GetValue())
	}
}

func TestMetricFamilyProtobufRoundTrip(t *testing.T) {
	originalCounter := BuildCounterMetricFamily(
		"rpc_requests_total",
		"Total RPC requests",
		map[string]string{"service": "auth"},
		42.0,
	)

	deserCounter, err := RoundTripMetricFamily(originalCounter)
	if err != nil {
		t.Fatalf("RoundTripMetricFamily counter failed: %v", err)
	}
	if !proto.Equal(originalCounter, deserCounter) {
		t.Fatalf("deserialized counter MetricFamily is not proto.Equal to original")
	}

	originalGauge := BuildGaugeMetricFamily(
		"active_connections",
		"Active network connections",
		map[string]string{"proto": "tcp"},
		128.0,
	)

	deserGauge, err := RoundTripMetricFamily(originalGauge)
	if err != nil {
		t.Fatalf("RoundTripMetricFamily gauge failed: %v", err)
	}
	if !proto.Equal(originalGauge, deserGauge) {
		t.Fatalf("deserialized gauge MetricFamily is not proto.Equal to original")
	}
}

{"case":{"caseId":"case:sha256:822bc1ac50ab7de389377165dad3878a91ceb0dcf1c11a1f525d251511241e59","contract":["MetricFamily initializes and organizes Prometheus metric data including Name, Help, MetricType, and Metric collections.","MetricFamily getter methods GetName, GetHelp, GetType, and GetMetric safely access protobuf fields with default zero-value fallbacks when receiver or fields are nil.","MetricFamily structures containing Counter and Gauge metrics with LabelPairs round-trip losslessly through protobuf serialization and deserialization."],"goal":"verify github.com/prometheus/client_model/go.MetricFamily in pkg:golang/github.com/prometheus/client_model@v0.0.0-20190812154241-14fe0d1b01d4","kind":"HOW","packages":["pkg:golang/github.com/prometheus/client_model@v0.0.0-20190812154241-14fe0d1b01d4"],"schemaVersion":1,"symbols":["github.com/prometheus/client_model/go.MetricFamily"]},"contractCommand":["go","test","./..."],"environment":{"arch":"x64","distro":"ubuntu","ecosystem":"golang","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@v0.0.0-20190812154241-14fe0d1b01d4"],"schemaVersion":1,"subject":"pkg:golang/github.com/prometheus/client_model@v0.0.0-20190812154241-14fe0d1b01d4","symbols":["github.com/prometheus/client_model/go.MetricFamily"],"verifierAdapter":"golang@1"}

module example.com/metricfamilysample

go 1.22.0

require (
	github.com/golang/protobuf v1.5.4
	github.com/prometheus/client_model v0.0.0-20190812154241-14fe0d1b01d4
)

require google.golang.org/protobuf v1.33.0 // indirect

github.com/golang/protobuf v1.2.0/go.mod h1:6lQm79b+lXiMfvg/cZm0SGofjICqVBUtrP5yJMmIC1U=
github.com/golang/protobuf v1.5.4 h1:i7eJL8qZTpSEXOPTxNKhASYpMn+8e5Q6AdndVa1dWek=
github.com/golang/protobuf v1.5.4/go.mod h1:lnTiLA8Wa4RWRcIUkrtSVa5nRhsEGBg48fD6rSs7xps=
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 v0.0.0-20190812154241-14fe0d1b01d4 h1:gQz4mCbXsO+nc9n1hCxHcGA3Zx3Eo+UHZoInFGUIXNM=
github.com/prometheus/client_model v0.0.0-20190812154241-14fe0d1b01d4/go.mod h1:xMI15A0UPsDsEKsMN9yxemIoYk6Tm2C1GtYGdfGttqA=
golang.org/x/sync v0.0.0-20181108010431-42b317875d0f/go.mod h1:RxMgew5VJxzue5/jJTE5uejpjVlOe/izrB70Jof72aM=
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 v1.33.0 h1:uNO2rsAINq/JlFpSdYEKIZ0uKD/R9cpdv0T+yoGwGmI=
google.golang.org/protobuf v1.33.0/go.mod h1:c6P6GXX6sHbq/GpV6MGZEdwhWPcYBgnhAHhKbcUYpos=

package sample

import (
	"sort"

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

// BuildCounterMetricFamily constructs a MetricFamily for counter metrics.
func BuildCounterMetricFamily(name, help string, labels map[string]string, value float64) *dto.MetricFamily {
	labelPairs := buildSortedLabelPairs(labels)

	metric := &dto.Metric{
		Label: labelPairs,
		Counter: &dto.Counter{
			Value: proto.Float64(value),
		},
	}

	return &dto.MetricFamily{
		Name:   proto.String(name),
		Help:   proto.String(help),
		Type:   dto.MetricType_COUNTER.Enum(),
		Metric: []*dto.Metric{metric},
	}
}

// BuildGaugeMetricFamily constructs a MetricFamily for gauge metrics.
func BuildGaugeMetricFamily(name, help string, labels map[string]string, value float64) *dto.MetricFamily {
	labelPairs := buildSortedLabelPairs(labels)

	metric := &dto.Metric{
		Label: labelPairs,
		Gauge: &dto.Gauge{
			Value: proto.Float64(value),
		},
	}

	return &dto.MetricFamily{
		Name:   proto.String(name),
		Help:   proto.String(help),
		Type:   dto.MetricType_GAUGE.Enum(),
		Metric: []*dto.Metric{metric},
	}
}

// RoundTripMetricFamily marshals and unmarshals a MetricFamily using protobuf.
func RoundTripMetricFamily(mf *dto.MetricFamily) (*dto.MetricFamily, error) {
	data, err := proto.Marshal(mf)
	if err != nil {
		return nil, err
	}
	out := &dto.MetricFamily{}
	if err := proto.Unmarshal(data, out); err != nil {
		return nil, err
	}
	return out, nil
}

func buildSortedLabelPairs(labels map[string]string) []*dto.LabelPair {
	if len(labels) == 0 {
		return nil
	}
	keys := make([]string, 0, len(labels))
	for k := range labels {
		keys = append(keys, k)
	}
	sort.Strings(keys)

	pairs := make([]*dto.LabelPair, 0, len(keys))
	for _, k := range keys {
		pairs = append(pairs, &dto.LabelPair{
			Name:  proto.String(k),
			Value: proto.String(labels[k]),
		})
	}
	return pairs
}

{
  "schemaVersion": 1,
  "goal": "verify github.com/prometheus/client_model/go.MetricFamily in pkg:golang/github.com/prometheus/client_model@v0.0.0-20190812154241-14fe0d1b01d4",
  "kind": "HOW",
  "packages": [
    "pkg:golang/github.com/prometheus/client_model@v0.0.0-20190812154241-14fe0d1b01d4"
  ],
  "symbols": [
    "github.com/prometheus/client_model/go.MetricFamily"
  ]
}