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

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.ConfigState 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.ConfigState
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:sha256:1b0106172bc43f49ce01e6b113e3fcf1759bddc74cbb5ef4ccd4e7955fd1cc4e","contract":["ConfigState.Sdump formats data structures with custom Indent, DisablePointerAddresses, and DisableCapacities settings","ConfigState.Sprintf formats values with spew syntax like %#v","ConfigState.Fdump writes formatted struct dumps directly to an io.Writer"],"goal":"verify spew.ConfigState 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.ConfigState"]},"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.ConfigState"],"verifierAdapter":"golang@1"}

module example.com/sample

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=

package main

import (
	"fmt"

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

type User struct {
	ID   int
	Name string
	Tags []string
}

func main() {
	cs := spew.ConfigState{
		Indent:                  "  ",
		DisablePointerAddresses: true,
		DisableCapacities:       true,
		SortKeys:                true,
	}

	user := User{
		ID:   42,
		Name: "Alice",
		Tags: []string{"admin", "user"},
	}

	dump := cs.Sdump(user)
	fmt.Print(dump)
}

{
  "schemaVersion": 1,
  "goal": "verify spew.ConfigState 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.ConfigState"
  ],
  "constraints": {
    "executionContext": "node"
  },
  "runtimeConditions": {
    "ecosystem": "npm",
    "language": "javascript",
    "moduleSystem": "cjs",
    "packageManager": "npm@10.9.8",
    "runtime": "node@22.23.2"
  }
}

package main

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

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

type Item struct {
	ID    int
	Name  string
	Attrs map[string]string
}

func main() {
	// Assertion 1: ConfigState.Sdump formats data structures with custom Indent and DisablePointerAddresses settings
	cs := spew.ConfigState{
		Indent:                  "  ",
		DisablePointerAddresses: true,
		DisableCapacities:       true,
		SortKeys:                true,
	}

	item := &Item{
		ID:   101,
		Name: "Widget",
		Attrs: map[string]string{
			"color": "blue",
		},
	}

	dump := cs.Sdump(item)
	if !strings.Contains(dump, "(*main.Item)") {
		fmt.Fprintf(os.Stderr, "assertion 1 failed: expected (*main.Item) in dump, got: %s\n", dump)
		os.Exit(1)
	}
	if !strings.Contains(dump, "ID: (int) 101") {
		fmt.Fprintf(os.Stderr, "assertion 1 failed: expected 'ID: (int) 101' in dump, got: %s\n", dump)
		os.Exit(1)
	}
	if !strings.Contains(dump, "Name: (string) (len=6) \"Widget\"") {
		fmt.Fprintf(os.Stderr, "assertion 1 failed: expected string length in dump, got: %s\n", dump)
		os.Exit(1)
	}

	// Assertion 2: ConfigState.Sprintf formats values with spew syntax like %#v
	formatted := cs.Sprintf("%#v", item)
	if !strings.Contains(formatted, "ID:(int)101") || !strings.Contains(formatted, "Name:(string)Widget") {
		fmt.Fprintf(os.Stderr, "assertion 2 failed: unexpected Sprintf output: %s\n", formatted)
		os.Exit(1)
	}

	// Assertion 3: ConfigState.Fdump writes formatted struct dumps directly to an io.Writer
	var buf bytes.Buffer
	cs.Fdump(&buf, item)
	fdumpOutput := buf.String()
	if fdumpOutput != dump {
		fmt.Fprintf(os.Stderr, "assertion 3 failed: Fdump output does not match Sdump output\ngot:\n%s\nexpected:\n%s\n", fdumpOutput, dump)
		os.Exit(1)
	}

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