github.com/prometheus/client_model v0.2.0: go.MetricType_COUNTER

# prometheus client_model MetricType_COUNTER Verification Notes

## Search Results
An initial search via `search_known_solution` for `pkg:golang/github.com/prometheus/client_model@v0.2.0` with `github.com/prometheus/client_model/go.MetricType_COUNTER` was conducted.

## Pinned Version
- Package: `github.com/prometheus/client_model`
- Release: `v0.2.0` (in `go.mod` / `go.sum`)

## Observed Behavior
1. **MetricType_COUNTER Enum Constant**:
   - `dto.MetricType_COUNTER` is a typed constant of enum type `dto.MetricType` equal to `0`.
   - `dto.MetricType_COUNTER.String()` returns `"COUNTER"`.
   - `dto.MetricType_COUNTER.Enum()` returns `*dto.MetricType`.
   - `dto.MetricType_name` and `dto.MetricType_value` map between string representation and int32 representation.
2. **MetricFamily Integration & Protobuf Serialization**:
   - `dto.MetricFamily` configured with `Type: dto.MetricType_COUNTER.Enum()` contains metrics with `Counter` definitions and roundtrips through protobuf serialization without data loss.
3. **JSON Unmarshaling**:
   - `dto.MetricType` unmarshals both string `"COUNTER"` and integer `0` to `dto.MetricType_COUNTER`.

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.MetricType_COUNTER in pkg:golang/github.com/prometheus/client_model@v0.2.0
Kind: HOW

Use EXACTLY these public packages and versions:
  - pkg:golang/github.com/prometheus/client_model@v0.2.0
Demonstrate these symbols/APIs:
  - github.com/prometheus/client_model/go.MetricType_COUNTER
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.

package clientmodelcounter_test

import (
	"encoding/json"
	"testing"

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

func TestMetricTypeCounterConstantAndProperties(t *testing.T) {
	// Verify MetricType_COUNTER enum value
	if dto.MetricType_COUNTER != 0 {
		t.Fatalf("expected MetricType_COUNTER == 0, got %d", dto.MetricType_COUNTER)
	}

	// Verify String() method returns "COUNTER"
	if str := dto.MetricType_COUNTER.String(); str != "COUNTER" {
		t.Fatalf("expected MetricType_COUNTER.String() == %q, got %q", "COUNTER", str)
	}

	// Verify Enum() returns pointer to MetricType_COUNTER
	enumPtr := dto.MetricType_COUNTER.Enum()
	if enumPtr == nil || *enumPtr != dto.MetricType_COUNTER {
		t.Fatalf("expected Enum() to return pointer to MetricType_COUNTER, got %v", enumPtr)
	}

	// Verify name and value mappings
	if name, ok := dto.MetricType_name[int32(dto.MetricType_COUNTER)]; !ok || name != "COUNTER" {
		t.Fatalf("expected MetricType_name mapping to COUNTER, got %q (ok=%v)", name, ok)
	}
	if val, ok := dto.MetricType_value["COUNTER"]; !ok || val != int32(dto.MetricType_COUNTER) {
		t.Fatalf("expected MetricType_value mapping for COUNTER to 0, got %d (ok=%v)", val, ok)
	}
}

func TestMetricFamilyWithCounter(t *testing.T) {
	metricName := "http_requests_total"
	metricHelp := "Total number of HTTP requests processed"
	counterValue := 1024.0
	labelName := "method"
	labelValue := "GET"

	family := &dto.MetricFamily{
		Name: &metricName,
		Help: &metricHelp,
		Type: dto.MetricType_COUNTER.Enum(),
		Metric: []*dto.Metric{
			{
				Label: []*dto.LabelPair{
					{
						Name:  &labelName,
						Value: &labelValue,
					},
				},
				Counter: &dto.Counter{
					Value: &counterValue,
				},
			},
		},
	}

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

	metrics := family.GetMetric()
	if len(metrics) != 1 {
		t.Fatalf("expected 1 metric in family, got %d", len(metrics))
	}
	if metrics[0].GetCounter() == nil {
		t.Fatal("expected counter in metric to be non-nil")
	}
	if metrics[0].GetCounter().GetValue() != counterValue {
		t.Errorf("expected counter value %f, got %f", counterValue, metrics[0].GetCounter().GetValue())
	}

	// Protobuf serialization roundtrip
	data, err := proto.Marshal(family)
	if err != nil {
		t.Fatalf("failed to marshal MetricFamily: %v", err)
	}

	var decoded dto.MetricFamily
	if err := proto.Unmarshal(data, &decoded); err != nil {
		t.Fatalf("failed to unmarshal MetricFamily: %v", err)
	}
	if decoded.GetType() != dto.MetricType_COUNTER {
		t.Fatalf("expected unmarshaled type %v, got %v", dto.MetricType_COUNTER, decoded.GetType())
	}
	if len(decoded.GetMetric()) != 1 || decoded.GetMetric()[0].GetCounter().GetValue() != counterValue {
		t.Fatalf("unmarshaled counter metric does not match original")
	}
}

func TestMetricTypeJSONUnmarshal(t *testing.T) {
	var mt dto.MetricType
	if err := json.Unmarshal([]byte(`"COUNTER"`), &mt); err != nil {
		t.Fatalf("failed to unmarshal JSON \"COUNTER\": %v", err)
	}
	if mt != dto.MetricType_COUNTER {
		t.Fatalf("expected unmarshaled JSON to be MetricType_COUNTER, got %v", mt)
	}

	if err := json.Unmarshal([]byte(`0`), &mt); err != nil {
		t.Fatalf("failed to unmarshal numeric JSON 0: %v", err)
	}
	if mt != dto.MetricType_COUNTER {
		t.Fatalf("expected unmarshaled numeric 0 to be MetricType_COUNTER, got %v", mt)
	}
}

{"case":{"caseId":"case:sha256:e759102d05d81cecaf31fac0baea3fc0093e0c8440b34dd62787418afaf47695","contract":["dto.MetricType_COUNTER is an enum constant of type dto.MetricType with value 0 representing Prometheus counter metrics.","dto.MetricType_COUNTER has String representation 'COUNTER', Enum helper returning *MetricType, and maps in MetricType_name and MetricType_value.","dto.MetricFamily configured with Type MetricType_COUNTER.Enum() stores counter metric values and roundtrips through protobuf marshal and unmarshal.","dto.MetricType unmarshals JSON string 'COUNTER' and numeric 0 to MetricType_COUNTER."],"goal":"verify github.com/prometheus/client_model/go.MetricType_COUNTER in pkg:golang/github.com/prometheus/client_model@v0.2.0","kind":"HOW","packages":["pkg:golang/github.com/prometheus/client_model@v0.2.0"],"schemaVersion":1,"symbols":["github.com/prometheus/client_model/go.MetricType_COUNTER"]},"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@v0.2.0"],"schemaVersion":1,"subject":"pkg:golang/github.com/prometheus/client_model@v0.2.0","symbols":["github.com/prometheus/client_model/go.MetricType_COUNTER"],"verifierAdapter":"golang@1"}

module example.com/clientmodelcounter

go 1.22

require (
	github.com/golang/protobuf v1.5.0
	github.com/prometheus/client_model v0.2.0
)

require google.golang.org/protobuf v1.26.0-rc.1 // indirect

github.com/golang/protobuf v1.2.0/go.mod h1:6lQm79b+lXiMfvg/cZm0SGofjICqVBUtrP5yJMmIC1U=
github.com/golang/protobuf v1.5.0 h1:LUVKkCeviFUMKqHa4tXIIij/lbhnMbP7Fn5wKdKkRh4=
github.com/golang/protobuf v1.5.0/go.mod h1:FsONVRAS9T7sI+LIUmWTfcYkHO4aIWwzhcaSAoJOfIk=
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 v0.2.0 h1:uq5h0d+GuxiXLJLNABMgp2qUWDPiLvgCzz2dUR+/W/M=
github.com/prometheus/client_model v0.2.0/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 v1.26.0-rc.1 h1:7QnIQpGRHE5RnLKnESfDoxm2dTapTZua5a0kS0A+VXQ=
google.golang.org/protobuf v1.26.0-rc.1/go.mod h1:jlhhOSvTdKEhbULTjvd4ARK9grFBp09yW+WbY/TyQbw=

{
  "schemaVersion": 1,
  "goal": "verify github.com/prometheus/client_model/go.MetricType_COUNTER in pkg:golang/github.com/prometheus/client_model@v0.2.0",
  "kind": "HOW",
  "packages": [
    "pkg:golang/github.com/prometheus/client_model@v0.2.0"
  ],
  "symbols": [
    "github.com/prometheus/client_model/go.MetricType_COUNTER"
  ],
  "constraints": {
    "executionContext": "node"
  },
  "runtimeConditions": {
    "ecosystem": "npm",
    "language": "javascript",
    "moduleSystem": "cjs",
    "packageManager": "npm@10.9.8",
    "runtime": "node@22.23.2"
  }
}