golang.org/x/net v0.47.0: atom.Span

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 golang.org/x/net/html/atom.Span in pkg:golang/golang.org/x/net@v0.47.0
Kind: HOW

Use EXACTLY these public packages and versions:
  - pkg:golang/golang.org/x/net@v0.47.0
Demonstrate these symbols/APIs:
  - golang.org/x/net/html/atom.Span

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:a120097ef18aa2e68e9097baecad49d7cdeaf256ac65d9052ff5762cde090f9a","contract":["atom.Span constant is non-zero and atom.Span.String returns \"span\"","atom.Lookup on byte slice \"span\" returns atom.Span while case-mismatched or unknown input returns 0","atom.String on byte slice \"span\" returns identical string value \"span\""],"goal":"verify golang.org/x/net/html/atom.Span in pkg:golang/golang.org/x/net@v0.47.0","kind":"HOW","packages":["pkg:golang/golang.org/x/net@v0.47.0"],"schemaVersion":1,"symbols":["golang.org/x/net/html/atom.Span"]},"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/golang.org/x/net@v0.47.0"],"schemaVersion":1,"subject":"pkg:golang/golang.org/x/net@v0.47.0","symbols":["golang.org/x/net/html/atom.Span"],"verifierAdapter":"golang@1"}

module example.com/sample

go 1.26.6

require golang.org/x/net v0.47.0

golang.org/x/net v0.47.0 h1:Mx+4dIFzqraBXUugkia1OOvlD6LemFo1ALMHjrXDOhY=
golang.org/x/net v0.47.0/go.mod h1:/jNxtkgq5yWUGYkaZGqo27cfGZ1c5Nen03aYrrKpVRU=

package main

import (
	"fmt"

	"golang.org/x/net/html/atom"
)

func main() {
	spanAtom := atom.Span
	fmt.Printf("Atom: %d, String: %s\n", spanAtom, spanAtom.String())

	lookedUp := atom.Lookup([]byte("span"))
	fmt.Printf("Lookup 'span': %d (matches atom.Span: %t)\n", lookedUp, lookedUp == spanAtom)
}

{
  "schemaVersion": 1,
  "goal": "verify golang.org/x/net/html/atom.Span in pkg:golang/golang.org/x/net@v0.47.0",
  "kind": "HOW",
  "packages": [
    "pkg:golang/golang.org/x/net@v0.47.0"
  ],
  "symbols": [
    "golang.org/x/net/html/atom.Span"
  ]
}

package main

import (
	"fmt"
	"os"

	"golang.org/x/net/html/atom"
)

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

func runContractTests() error {
	// 1. atom.Span constant is non-zero and atom.Span.String returns "span"
	if atom.Span == 0 {
		return fmt.Errorf("expected atom.Span != 0, got 0")
	}
	if got := atom.Span.String(); got != "span" {
		return fmt.Errorf("expected atom.Span.String() == %q, got %q", "span", got)
	}

	// 2. atom.Lookup on byte slice "span" returns atom.Span while case-mismatched or unknown input returns 0
	if lookedUp := atom.Lookup([]byte("span")); lookedUp != atom.Span {
		return fmt.Errorf("expected atom.Lookup([]byte(\"span\")) == atom.Span (%d), got %d", atom.Span, lookedUp)
	}
	if upper := atom.Lookup([]byte("SPAN")); upper != 0 {
		return fmt.Errorf("expected atom.Lookup([]byte(\"SPAN\")) == 0, got %d", upper)
	}
	if unknown := atom.Lookup([]byte("unknown_tag_xyz")); unknown != 0 {
		return fmt.Errorf("expected atom.Lookup(unknown) == 0, got %d", unknown)
	}

	// 3. atom.String on byte slice "span" returns identical string value "span"
	if s := atom.String([]byte("span")); s != "span" {
		return fmt.Errorf("expected atom.String([]byte(\"span\")) == %q, got %q", "span", s)
	}

	return nil
}