github.com/davecgh/go-spew v1.1.1: spew.Sdump

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 spew.Sdump in pkg:golang/github.com/davecgh/go-spew@v1.1.1
Kind: HOW

Use EXACTLY these public packages and versions:
  - pkg:golang/github.com/davecgh/go-spew@v1.1.1
Demonstrate these symbols/APIs:
  - spew.Sdump
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.

{"case":{"caseId":"case:sha256:d3f854a5cf48b13e1f33bef23dce2980773d5a1ec567fb6b48e343d535973aa4","contract":["spew.Sdump formats basic types, structs, slices, and maps into detailed string representations","spew.Sdump includes type names and pointer addresses in dump output","spew.Sdump handles circular references without infinite recursion"],"goal":"verify spew.Sdump in pkg:golang/github.com/davecgh/go-spew@v1.1.1","kind":"HOW","packages":["pkg:golang/github.com/davecgh/go-spew@v1.1.1"],"schemaVersion":1,"symbols":["spew.Sdump"]},"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/github.com/davecgh/go-spew@v1.1.1"],"schemaVersion":1,"subject":"pkg:golang/github.com/davecgh/go-spew@v1.1.1","symbols":["spew.Sdump"],"verifierAdapter":"golang@1"}

module sample

go 1.21

require github.com/davecgh/go-spew v1.1.1

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=

{
  "schemaVersion": 1,
  "goal": "verify spew.Sdump in pkg:golang/github.com/davecgh/go-spew@v1.1.1",
  "kind": "HOW",
  "packages": [
    "pkg:golang/github.com/davecgh/go-spew@v1.1.1"
  ],
  "symbols": [
    "spew.Sdump"
  ],
  "constraints": {
    "executionContext": "node"
  },
  "runtimeConditions": {
    "ecosystem": "npm",
    "language": "javascript",
    "moduleSystem": "cjs",
    "packageManager": "npm@10.9.8",
    "runtime": "node@22.23.2"
  }
}

package main

import (
	"fmt"
	"os"
	"strings"

	"github.com/davecgh/go-spew/spew"
)

type CustomItem struct {
	ID    int
	Title string
}

type Node struct {
	Value int
	Next  *Node
}

func main() {
	if err := runTests(); err != nil {
		fmt.Fprintf(os.Stderr, "Contract test failed: %v\n", err)
		os.Exit(1)
	}
	fmt.Println("All contract tests passed.")
}

func runTests() error {
	// 1. Basic formatting of struct, slice, and map
	item := CustomItem{ID: 42, Title: "example"}
	dump := spew.Sdump(item)
	if !strings.Contains(dump, "main.CustomItem") || !strings.Contains(dump, "ID: (int) 42") || !strings.Contains(dump, `Title: (string) (len=7) "example"`) {
		return fmt.Errorf("unexpected struct dump format: %s", dump)
	}

	dataMap := map[string][]int{
		"primes": {2, 3, 5},
	}
	mapDump := spew.Sdump(dataMap)
	if !strings.Contains(mapDump, "map[string][]int") || !strings.Contains(mapDump, "primes") || !strings.Contains(mapDump, "(int) 2") {
		return fmt.Errorf("unexpected map dump format: %s", mapDump)
	}

	// 2. Circular reference handling
	n1 := &Node{Value: 1}
	n2 := &Node{Value: 2}
	n1.Next = n2
	n2.Next = n1

	circularDump := spew.Sdump(n1)
	if !strings.Contains(circularDump, "<already shown>") {
		return fmt.Errorf("circular reference dump missing <already shown>: %s", circularDump)
	}

	return nil
}