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

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 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

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:cc1e99cc1eaf2da0abdd4620d7ac46c76edb430e437ac3760828fb4a834d469d","contract":["spew.Sdump formats primitives, structs, and nested pointers with full type information and field names","spew.ConfigState with DisablePointerAddresses omits pointer memory addresses from dump output","spew.ConfigState with SortKeys produces deterministic sorted output for map entries","spew.ConfigState with MaxDepth limits traversal depth of nested structures and emits max depth reached","spew.Fdump writes formatted deep dumps directly to an io.Writer","spew.Sprintf formats structs using spew-specific verbs such as %#+v with type annotations"],"goal":"verify 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},"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","verifierAdapter":"golang@1"}

module sample-go-spew

go 1.22

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 pkg:golang/github.com/davecgh/go-spew@v1.1.1",
  "kind": "HOW",
  "packages": [
    "pkg:golang/github.com/davecgh/go-spew@v1.1.1"
  ]
}

package main

import (
	"bytes"
	"fmt"
	"os"
	"strings"

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

type SampleItem struct {
	Name  string
	Count int
}

type LinkedNode struct {
	Value string
	Next  *LinkedNode
}

func main() {
	// 1. spew.Sdump formats primitives, structs, and nested pointers with full type information and field names
	{
		item := SampleItem{Name: "widget", Count: 10}
		dump := spew.Sdump(item)
		if !strings.Contains(dump, "(main.SampleItem)") {
			fmt.Fprintf(os.Stderr, "Contract 1 failed: missing type name: %s\n", dump)
			os.Exit(1)
		}
		if !strings.Contains(dump, "Name: (string) (len=6) \"widget\"") {
			fmt.Fprintf(os.Stderr, "Contract 1 failed: missing Name field: %s\n", dump)
			os.Exit(1)
		}
		if !strings.Contains(dump, "Count: (int) 10") {
			fmt.Fprintf(os.Stderr, "Contract 1 failed: missing Count field: %s\n", dump)
			os.Exit(1)
		}
	}

	// 2. spew.ConfigState with DisablePointerAddresses omits pointer memory addresses from dump output
	{
		num := 100
		ptr := &num
		cs := spew.ConfigState{
			DisablePointerAddresses: true,
			Indent:                  " ",
		}
		dump := cs.Sdump(ptr)
		if !strings.Contains(dump, "(*int)(100)") {
			fmt.Fprintf(os.Stderr, "Contract 2 failed: expected (*int)(100), got: %s\n", dump)
			os.Exit(1)
		}
		if strings.Contains(dump, "0x") {
			fmt.Fprintf(os.Stderr, "Contract 2 failed: dump contains pointer address: %s\n", dump)
			os.Exit(1)
		}
	}

	// 3. spew.ConfigState with SortKeys produces deterministic sorted output for map entries
	{
		data := map[string]int{
			"delta": 4,
			"alpha": 1,
			"gamma": 3,
			"beta":  2,
		}
		cs := spew.ConfigState{
			SortKeys: true,
			Indent:   " ",
		}
		dump := cs.Sdump(data)
		posA := strings.Index(dump, "(string) (len=5) \"alpha\"")
		posB := strings.Index(dump, "(string) (len=4) \"beta\"")
		posD := strings.Index(dump, "(string) (len=5) \"delta\"")
		posG := strings.Index(dump, "(string) (len=5) \"gamma\"")
		if posA == -1 || posB == -1 || posD == -1 || posG == -1 {
			fmt.Fprintf(os.Stderr, "Contract 3 failed: missing map keys: %s\n", dump)
			os.Exit(1)
		}
		if !(posA < posB && posB < posD && posD < posG) {
			fmt.Fprintf(os.Stderr, "Contract 3 failed: map keys are not sorted: %s\n", dump)
			os.Exit(1)
		}
	}

	// 4. spew.ConfigState with MaxDepth limits traversal depth of nested structures and emits max depth reached
	{
		n1 := &LinkedNode{Value: "first"}
		n2 := &LinkedNode{Value: "second"}
		n3 := &LinkedNode{Value: "third"}
		n1.Next = n2
		n2.Next = n3

		cs := spew.ConfigState{
			MaxDepth:                2,
			DisablePointerAddresses: true,
			Indent:                  " ",
		}
		dump := cs.Sdump(n1)
		if !strings.Contains(dump, "<max depth reached>") {
			fmt.Fprintf(os.Stderr, "Contract 4 failed: expected <max depth reached>: %s\n", dump)
			os.Exit(1)
		}
		if strings.Contains(dump, "third") {
			fmt.Fprintf(os.Stderr, "Contract 4 failed: depth limit exceeded, contains third: %s\n", dump)
			os.Exit(1)
		}
	}

	// 5. spew.Fdump writes formatted deep dumps directly to an io.Writer
	{
		var buf bytes.Buffer
		item := SampleItem{Name: "gadget", Count: 5}
		spew.Fdump(&buf, item)
		out := buf.String()
		if !strings.Contains(out, "(main.SampleItem)") || !strings.Contains(out, "gadget") {
			fmt.Fprintf(os.Stderr, "Contract 5 failed: Fdump output unexpected: %s\n", out)
			os.Exit(1)
		}
	}

	// 6. spew.Sprintf formats structs using spew-specific verbs such as %#+v with type annotations
	{
		item := SampleItem{Name: "device", Count: 7}
		formatted := spew.Sprintf("%#+v", item)
		if !strings.Contains(formatted, "(main.SampleItem)") || !strings.Contains(formatted, "device") {
			fmt.Fprintf(os.Stderr, "Contract 6 failed: Sprintf %#+v output unexpected: %s\n", formatted)
			os.Exit(1)
		}
	}

	fmt.Println("All contract assertions passed.")
}