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

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.TestingT 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.TestingT

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:sha256:618740292874685f96bbe286ab46ee44c289216c2f0de4bbe6652a6a9aeef0f7","contract":["custom Recorder satisfies goleak.TestingT interface","goleak.VerifyNone does not report error to TestingT when no goroutines leak","goleak.VerifyNone reports error to TestingT when an unexpected goroutine leaks"],"goal":"verify go.uber.org/goleak.TestingT 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.TestingT"]},"contractCommand":["go","run","./test"],"environment":{"arch":"x64","distro":"ubuntu","ecosystem":"golang","language":"go","libc":"glibc","libcVersion":"2.39","os":"linux","osVersionBucket":"24","packageManager":"go","packageManagerVersion":"1.26.6","runtime":"go","runtimeVersion":"1.26.6","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.TestingT"],"verifierAdapter":"golang@1"}

module example.com/goleak-testingt-sample

go 1.22.0

require go.uber.org/goleak v1.2.0

go.uber.org/goleak v1.2.0 h1:xqgm/S+aQvhWFTtR0XK3Jvg7z8kGV8P4X14IzwN3Eqk=
go.uber.org/goleak v1.2.0/go.mod h1:XJYK+MuIchqpmGmUSAzotztawfKvYLUIgg7guXrwVUo=

package sample

import (
	"fmt"
	"strings"

	"go.uber.org/goleak"
)

// Recorder implements goleak.TestingT to record leak errors.
type Recorder struct {
	errors []string
}

// Ensure Recorder implements goleak.TestingT.
var _ goleak.TestingT = (*Recorder)(nil)

// Error records error messages passed by goleak.
func (r *Recorder) Error(args ...interface{}) {
	var parts []string
	for _, a := range args {
		parts = append(parts, fmt.Sprint(a))
	}
	r.errors = append(r.errors, strings.Join(parts, " "))
}

// Errors returns all recorded error messages.
func (r *Recorder) Errors() []string {
	return r.errors
}

// HasErrors returns true if any errors were recorded.
func (r *Recorder) HasErrors() bool {
	return len(r.errors) > 0
}

// CheckLeaks runs goleak.VerifyNone using the provided goleak.TestingT implementation.
func CheckLeaks(t goleak.TestingT, options ...goleak.Option) {
	goleak.VerifyNone(t, options...)
}

{
  "schemaVersion": 1,
  "goal": "verify go.uber.org/goleak.TestingT 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.TestingT"
  ]
}

package main

import (
	"fmt"
	"os"
	"strings"
	"sync"
	"time"

	sample "example.com/goleak-testingt-sample"
	"go.uber.org/goleak"
)

func runWorker(stop <-chan struct{}, ready *sync.WaitGroup) {
	ready.Done()
	<-stop
}

func main() {
	// Assertion 1: custom Recorder satisfies goleak.TestingT interface
	var t goleak.TestingT = &sample.Recorder{}
	if t == nil {
		fmt.Fprintf(os.Stderr, "FAIL: expected non-nil TestingT implementation\n")
		os.Exit(1)
	}

	// Assertion 2: goleak.VerifyNone does not report error to TestingT when no goroutines leak
	recClean := &sample.Recorder{}
	stopClean := make(chan struct{})
	doneClean := make(chan struct{})
	go func() {
		defer close(doneClean)
		<-stopClean
	}()
	close(stopClean)
	<-doneClean

	sample.CheckLeaks(recClean)
	if recClean.HasErrors() {
		fmt.Fprintf(os.Stderr, "FAIL: expected no errors when no goroutine leaks, got: %v\n", recClean.Errors())
		os.Exit(1)
	}

	// Assertion 3: goleak.VerifyNone reports error to TestingT when an unexpected goroutine leaks
	recLeak := &sample.Recorder{}
	stopLeak := make(chan struct{})
	var wg sync.WaitGroup
	wg.Add(1)
	go runWorker(stopLeak, &wg)
	wg.Wait()

	sample.CheckLeaks(recLeak)
	if !recLeak.HasErrors() {
		fmt.Fprintf(os.Stderr, "FAIL: expected error reported to TestingT when goroutine leaks, got none\n")
		os.Exit(1)
	}
	if !strings.Contains(recLeak.Errors()[0], "found unexpected goroutines") {
		fmt.Fprintf(os.Stderr, "FAIL: expected leak error message, got: %s\n", recLeak.Errors()[0])
		os.Exit(1)
	}
	close(stopLeak)

	time.Sleep(50 * time.Millisecond)

	fmt.Println("PASS: verify go.uber.org/goleak.TestingT contract passed")
}