go.uber.org/goleak v1.2.0: IgnoreTopFunction

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.uber.org/goleak.IgnoreTopFunction in pkg:golang/go.uber.org/goleak@v1.2.0
Kind: HOW

Use EXACTLY these public packages and versions:
  - pkg:golang/go.uber.org/goleak@v1.2.0
Demonstrate these symbols/APIs:
  - go.uber.org/goleak.IgnoreTopFunction

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:sha256:6545917b5b81712ff327827ac7e11cc12e8a673414643566ab37146dc1136589","contract":["IgnoreTopFunction creates an Option that filters goroutines matching the specified top function name.","goleak.Find detects an unignored background goroutine and returns a non-nil error.","goleak.Find returns nil when a background goroutine matches the IgnoreTopFunction filter.","IgnoreTopFunction does not filter goroutines with non-matching top function names.","Multiple IgnoreTopFunction options can be combined to ignore multiple background goroutines simultaneously."],"goal":"verify go.uber.org/goleak.IgnoreTopFunction in pkg:golang/go.uber.org/goleak@v1.2.0","kind":"HOW","packages":["pkg:golang/go.uber.org/goleak@v1.2.0"],"schemaVersion":1,"symbols":["go.uber.org/goleak.IgnoreTopFunction"]},"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.uber.org/goleak@v1.2.0"],"schemaVersion":1,"subject":"pkg:golang/go.uber.org/goleak@v1.2.0","symbols":["go.uber.org/goleak.IgnoreTopFunction"],"verifierAdapter":"golang@1"}

module example.com/ignoretopfunction

go 1.26.6

require go.uber.org/goleak v1.2.0

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/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 v1.8.0 h1:pSgiaMZlXftHpm5L7V1+rVB+AZJydKsMxsQBIJw4PKk=
github.com/stretchr/testify v1.8.0/go.mod h1:yNjHg4UonilssWZ8iaSj1OCr/vHnekPRkoO+kdMU+MU=
go.uber.org/goleak v1.2.0 h1:xqgm/S+aQvhWFTtR0XK3Jvg7z8kGV8P4X14IzwN3Eqk=
go.uber.org/goleak v1.2.0/go.mod h1:XJYK+MuIchqpmGmUSAzotztawfKvYLUIgg7guXrwVUo=
golang.org/x/lint v0.0.0-20190930215403-16217165b5de h1:5hukYrvBGR8/eNkX5mdUezrA6JiaEZDtJb9Ei+1LlBs=
golang.org/x/lint v0.0.0-20190930215403-16217165b5de/go.mod h1:6SW0HCj/g11FgYtHlgUYUwCkIfeOF89ocIRzGO/8vkc=
golang.org/x/tools v0.1.5 h1:ouewzE6p+/VEB31YYnTbEJdi8pFqKp4P4n85vwo3DHA=
golang.org/x/tools v0.1.5/go.mod h1:o0xws9oXOQQZyjljx8fwUC0k7L1pTE6eaCbjGeHmOkk=
gopkg.in/yaml.v3 v3.0.1 h1:fxVm/GzAzEWqLHuvctI91KS9hhNmmWOoWu0XTYJS7CA=
gopkg.in/yaml.v3 v3.0.1/go.mod h1:K4uyk7z7BCEPqu6E+C64Yfv1cQ7kz7rIZviUmN+EgEM=

package main

import (
	"fmt"

	"go.uber.org/goleak"
)

// backgroundWorker represents an intentional background goroutine.
func backgroundWorker(started chan struct{}, stop chan struct{}) {
	close(started)
	<-stop
}

func main() {
	started := make(chan struct{})
	stop := make(chan struct{})

	// Start a background worker goroutine.
	go backgroundWorker(started, stop)
	<-started

	// 1. Without options, goleak.Find detects the background worker as an unexpected goroutine.
	if err := goleak.Find(); err != nil {
		fmt.Println("Detected unignored background goroutine as expected.")
	}

	// 2. IgnoreTopFunction ignores goroutines whose top stack frame matches the given function name.
	if err := goleak.Find(goleak.IgnoreTopFunction("main.backgroundWorker")); err == nil {
		fmt.Println("goleak.Find returned nil when backgroundWorker was ignored via IgnoreTopFunction.")
	}

	// 3. Clean up the worker goroutine and verify all goroutines are gone.
	close(stop)
	if err := goleak.Find(); err == nil {
		fmt.Println("All goroutines cleaned up successfully.")
	}
}

{
  "schemaVersion": 1,
  "goal": "verify go.uber.org/goleak.IgnoreTopFunction in pkg:golang/go.uber.org/goleak@v1.2.0",
  "kind": "HOW",
  "packages": [
    "pkg:golang/go.uber.org/goleak@v1.2.0"
  ],
  "symbols": [
    "go.uber.org/goleak.IgnoreTopFunction"
  ]
}

package main

import (
	"fmt"
	"os"

	"go.uber.org/goleak"
)

func workerAlpha(started chan struct{}, stop chan struct{}) {
	close(started)
	<-stop
}

func workerBeta(started chan struct{}, stop chan struct{}) {
	close(started)
	<-stop
}

func main() {
	// Assertion 1: IgnoreTopFunction creates an Option that filters goroutines matching the specified top function name.
	opt := goleak.IgnoreTopFunction("main.workerAlpha")
	if opt == nil {
		fmt.Fprintf(os.Stderr, "FAIL assertion 1: expected non-nil Option from IgnoreTopFunction\n")
		os.Exit(1)
	}

	stopA := make(chan struct{})
	startedA := make(chan struct{})
	go workerAlpha(startedA, stopA)
	<-startedA

	// Assertion 2: goleak.Find detects an unignored background goroutine and returns a non-nil error.
	if err := goleak.Find(); err == nil {
		fmt.Fprintf(os.Stderr, "FAIL assertion 2: expected error for unignored background goroutine, got nil\n")
		close(stopA)
		os.Exit(1)
	}

	// Assertion 3: goleak.Find returns nil when a background goroutine matches the IgnoreTopFunction filter.
	if err := goleak.Find(goleak.IgnoreTopFunction("main.workerAlpha")); err != nil {
		fmt.Fprintf(os.Stderr, "FAIL assertion 3: expected nil when background goroutine is ignored, got %v\n", err)
		close(stopA)
		os.Exit(1)
	}

	// Assertion 4: IgnoreTopFunction does not filter goroutines with non-matching top function names.
	if err := goleak.Find(goleak.IgnoreTopFunction("main.nonExistentWorker")); err == nil {
		fmt.Fprintf(os.Stderr, "FAIL assertion 4: expected error when filtering by non-matching function, got nil\n")
		close(stopA)
		os.Exit(1)
	}

	// Assertion 5: Multiple IgnoreTopFunction options can be combined to ignore multiple background goroutines simultaneously.
	stopB := make(chan struct{})
	startedB := make(chan struct{})
	go workerBeta(startedB, stopB)
	<-startedB

	if err := goleak.Find(goleak.IgnoreTopFunction("main.workerAlpha")); err == nil {
		fmt.Fprintf(os.Stderr, "FAIL assertion 5: expected error when only workerAlpha is ignored, got nil\n")
		close(stopA)
		close(stopB)
		os.Exit(1)
	}

	if err := goleak.Find(goleak.IgnoreTopFunction("main.workerBeta")); err == nil {
		fmt.Fprintf(os.Stderr, "FAIL assertion 5: expected error when only workerBeta is ignored, got nil\n")
		close(stopA)
		close(stopB)
		os.Exit(1)
	}

	if err := goleak.Find(goleak.IgnoreTopFunction("main.workerAlpha"), goleak.IgnoreTopFunction("main.workerBeta")); err != nil {
		fmt.Fprintf(os.Stderr, "FAIL assertion 5: expected nil when both workers are ignored, got %v\n", err)
		close(stopA)
		close(stopB)
		os.Exit(1)
	}

	close(stopA)
	close(stopB)

	if err := goleak.Find(); err != nil {
		fmt.Fprintf(os.Stderr, "FAIL: expected clean state after closing stop channels, got %v\n", err)
		os.Exit(1)
	}

	fmt.Println("All contract assertions verified successfully.")
}