go.opentelemetry.io/otel/sdk/metric v1.37.0: ErrReaderNotRegistered

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 go.opentelemetry.io/otel/sdk/metric.ErrReaderNotRegistered in pkg:golang/go.opentelemetry.io/otel/sdk/metric@v1.37.0
Kind: HOW

Use EXACTLY these public packages and versions:
  - pkg:golang/go.opentelemetry.io/otel/sdk/metric@v1.37.0
Demonstrate these symbols/APIs:
  - go.opentelemetry.io/otel/sdk/metric.ErrReaderNotRegistered

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:sha256:4ad6e46eb7ff9f8eefd1ada5d412fc3701ada1cb6dd3f8bad79aa4516bed8956","contract":["ErrReaderNotRegistered is defined as a sentinel error with message 'reader is not registered'","ManualReader.Collect returns ErrReaderNotRegistered before registration with MeterProvider","errors.Is matches the error returned by unregistered Collect against ErrReaderNotRegistered","Registering the reader with MeterProvider allows Collect to succeed without ErrReaderNotRegistered"],"goal":"verify go.opentelemetry.io/otel/sdk/metric.ErrReaderNotRegistered in pkg:golang/go.opentelemetry.io/otel/sdk/metric@v1.37.0","kind":"HOW","packages":["pkg:golang/go.opentelemetry.io/otel/sdk/metric@v1.37.0"],"schemaVersion":1,"symbols":["go.opentelemetry.io/otel/sdk/metric.ErrReaderNotRegistered"]},"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/go.opentelemetry.io/otel/sdk/metric@v1.37.0"],"schemaVersion":1,"subject":"pkg:golang/go.opentelemetry.io/otel/sdk/metric@v1.37.0","symbols":["go.opentelemetry.io/otel/sdk/metric.ErrReaderNotRegistered"],"verifierAdapter":"golang@1"}

module sample

go 1.23.0

require go.opentelemetry.io/otel/sdk/metric v1.37.0

require (
	github.com/go-logr/logr v1.4.3 // indirect
	github.com/go-logr/stdr v1.2.2 // indirect
	github.com/google/uuid v1.6.0 // indirect
	go.opentelemetry.io/auto/sdk v1.1.0 // indirect
	go.opentelemetry.io/otel v1.37.0 // indirect
	go.opentelemetry.io/otel/metric v1.37.0 // indirect
	go.opentelemetry.io/otel/sdk v1.37.0 // indirect
	go.opentelemetry.io/otel/trace v1.37.0 // indirect
	golang.org/x/sys v0.33.0 // indirect
)

github.com/davecgh/go-spew v1.1.1 h1:vj9j/u1bqnvCEfJOwUhtlOARqs3+rkHYY13jYWTU97c=
github.com/davecgh/go-spew v1.1.1/go.mod h1:J7Y8YcW2NihsgmVo/mv3lAwl/skON4iLHjSsI+c5H38=
github.com/go-logr/logr v1.2.2/go.mod h1:jdQByPbusPIv2/zmleS9BjJVeZ6kBagPoEUsqbVz/1A=
github.com/go-logr/logr v1.4.3 h1:CjnDlHq8ikf6E492q6eKboGOC0T8CDaOvkHCIg8idEI=
github.com/go-logr/logr v1.4.3/go.mod h1:9T104GzyrTigFIr8wt5mBrctHMim0Nb2HLGrmQ40KvY=
github.com/go-logr/stdr v1.2.2 h1:hSWxHoqTgW2S2qGc0LTAI563KZ5YKYRhT3MFKZMbjag=
github.com/go-logr/stdr v1.2.2/go.mod h1:mMo/vtBO5dYbehREoey6XUKy/eSumjCCveDpRre4VKE=
github.com/google/go-cmp v0.7.0 h1:wk8382ETsv4JYUZwIsn6YpYiWiBsYLSJiTsyBybVuN8=
github.com/google/go-cmp v0.7.0/go.mod h1:pXiqmnSA92OHEEa9HXL2W4E7lf9JzCmGVUdgjX3N/iU=
github.com/google/uuid v1.6.0 h1:NIvaJDMOsjHA8n1jAhLSgzrAzy1Hgr+hNrb57e+94F0=
github.com/google/uuid v1.6.0/go.mod h1:TIyPZe4MgqvfeYDBFedMoGGpEw/LqOeaOT+nhxU+yHo=
github.com/pmezard/go-difflib v1.0.0 h1:4DBwDE0NGyQoBHbLQYPwSUPoCMWR5BEzIk/f1lZbAQM=
github.com/pmezard/go-difflib v1.0.0/go.mod h1:iKH77koFhYxTK1pcRnkKkqfTogsbg7gZNVY4sRDYZ/4=
github.com/stretchr/testify v1.10.0 h1:Xv5erBjTwe/5IxqUQTdXv5kgmIvbHo3QQyRwhJsOfJA=
github.com/stretchr/testify v1.10.0/go.mod h1:r2ic/lqez/lEtzL7wO/rwa5dbSLXVDPFyf8C91i36aY=
go.opentelemetry.io/auto/sdk v1.1.0 h1:cH53jehLUN6UFLY71z+NDOiNJqDdPRaXzTel0sJySYA=
go.opentelemetry.io/auto/sdk v1.1.0/go.mod h1:3wSPjt5PWp2RhlCcmmOial7AvC4DQqZb7a7wCow3W8A=
go.opentelemetry.io/otel v1.37.0 h1:9zhNfelUvx0KBfu/gb+ZgeAfAgtWrfHJZcAqFC228wQ=
go.opentelemetry.io/otel v1.37.0/go.mod h1:ehE/umFRLnuLa/vSccNq9oS1ErUlkkK71gMcN34UG8I=
go.opentelemetry.io/otel/metric v1.37.0 h1:mvwbQS5m0tbmqML4NqK+e3aDiO02vsf/WgbsdpcPoZE=
go.opentelemetry.io/otel/metric v1.37.0/go.mod h1:04wGrZurHYKOc+RKeye86GwKiTb9FKm1WHtO+4EVr2E=
go.opentelemetry.io/otel/sdk v1.37.0 h1:ItB0QUqnjesGRvNcmAcU0LyvkVyGJ2xftD29bWdDvKI=
go.opentelemetry.io/otel/sdk v1.37.0/go.mod h1:VredYzxUvuo2q3WRcDnKDjbdvmO0sCzOvVAiY+yUkAg=
go.opentelemetry.io/otel/sdk/metric v1.37.0 h1:90lI228XrB9jCMuSdA0673aubgRobVZFhbjxHHspCPc=
go.opentelemetry.io/otel/sdk/metric v1.37.0/go.mod h1:cNen4ZWfiD37l5NhS+Keb5RXVWZWpRE+9WyVCpbo5ps=
go.opentelemetry.io/otel/trace v1.37.0 h1:HLdcFNbRQBE2imdSEgm/kwqmQj1Or1l/7bW6mxVK7z4=
go.opentelemetry.io/otel/trace v1.37.0/go.mod h1:TlgrlQ+PtQO5XFerSPUYG0JSgGyryXewPGyayAWSBS0=
golang.org/x/sys v0.33.0 h1:q3i8TbbEz+JRD9ywIRlyRAQbM0qF7hu24q3teo2hbuw=
golang.org/x/sys v0.33.0/go.mod h1:BJP2sWEmIv4KK5OTEluFJCKSidICx8ciO85XgH3Ak8k=
gopkg.in/yaml.v3 v3.0.1 h1:fxVm/GzAzEWqLHuvctI91KS9hhNmmWOoWu0XTYJS7CA=
gopkg.in/yaml.v3 v3.0.1/go.mod h1:K4uyk7z7BCEPqu6E+C64Yfv1cQ7kz7rIZviUmN+EgEM=

package sample

import (
	"context"
	"errors"

	"go.opentelemetry.io/otel/sdk/metric"
	"go.opentelemetry.io/otel/sdk/metric/metricdata"
)

// CollectUnregistered attempts to collect metrics from a ManualReader before registration.
// It returns ErrReaderNotRegistered if the reader has not been registered with a MeterProvider.
func CollectUnregistered(ctx context.Context, reader *metric.ManualReader) error {
	var rm metricdata.ResourceMetrics
	return reader.Collect(ctx, &rm)
}

// IsErrReaderNotRegistered checks whether the provided error is ErrReaderNotRegistered.
func IsErrReaderNotRegistered(err error) bool {
	return errors.Is(err, metric.ErrReaderNotRegistered)
}

// RegisterAndCollect registers the ManualReader with a MeterProvider and performs a collection.
func RegisterAndCollect(ctx context.Context, reader *metric.ManualReader) error {
	mp := metric.NewMeterProvider(metric.WithReader(reader))
	defer func() {
		_ = mp.Shutdown(ctx)
	}()

	var rm metricdata.ResourceMetrics
	return reader.Collect(ctx, &rm)
}

{
  "schemaVersion": 1,
  "goal": "verify go.opentelemetry.io/otel/sdk/metric.ErrReaderNotRegistered in pkg:golang/go.opentelemetry.io/otel/sdk/metric@v1.37.0",
  "kind": "HOW",
  "packages": [
    "pkg:golang/go.opentelemetry.io/otel/sdk/metric@v1.37.0"
  ],
  "symbols": [
    "go.opentelemetry.io/otel/sdk/metric.ErrReaderNotRegistered"
  ]
}

package main

import (
	"context"
	"errors"
	"fmt"
	"os"

	"go.opentelemetry.io/otel/sdk/metric"
	"sample"
)

func main() {
	ctx := context.Background()

	// 1. Verify ErrReaderNotRegistered sentinel error value and message
	if metric.ErrReaderNotRegistered == nil {
		fmt.Fprintln(os.Stderr, "FAIL: ErrReaderNotRegistered is nil")
		os.Exit(1)
	}
	if metric.ErrReaderNotRegistered.Error() != "reader is not registered" {
		fmt.Fprintf(os.Stderr, "FAIL: expected 'reader is not registered', got %q\n", metric.ErrReaderNotRegistered.Error())
		os.Exit(1)
	}

	// 2. Unregistered ManualReader returns ErrReaderNotRegistered on Collect
	unregisteredReader := metric.NewManualReader()
	err := sample.CollectUnregistered(ctx, unregisteredReader)
	if err == nil {
		fmt.Fprintln(os.Stderr, "FAIL: expected error on unregistered Collect, got nil")
		os.Exit(1)
	}
	if !sample.IsErrReaderNotRegistered(err) {
		fmt.Fprintf(os.Stderr, "FAIL: expected ErrReaderNotRegistered, got %v\n", err)
		os.Exit(1)
	}

	// 3. errors.Is correctly matches ErrReaderNotRegistered
	if !errors.Is(err, metric.ErrReaderNotRegistered) {
		fmt.Fprintf(os.Stderr, "FAIL: errors.Is did not match ErrReaderNotRegistered\n")
		os.Exit(1)
	}

	// 4. Registering with MeterProvider resolves ErrReaderNotRegistered on subsequent Collect
	registeredReader := metric.NewManualReader()
	if err := sample.RegisterAndCollect(ctx, registeredReader); err != nil {
		fmt.Fprintf(os.Stderr, "FAIL: RegisterAndCollect returned unexpected error: %v\n", err)
		os.Exit(1)
	}

	fmt.Println("PASS: ErrReaderNotRegistered verified")
}