golang.org/x/net v0.0.0-20210525063256-abc453219eb5: atom.Nav

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.Nav in pkg:golang/golang.org/x/net@v0.0.0-20210525063256-abc453219eb5
Kind: HOW

Use EXACTLY these public packages and versions:
  - pkg:golang/golang.org/x/net@v0.0.0-20210525063256-abc453219eb5
Demonstrate these symbols/APIs:
  - golang.org/x/net/html/atom.Nav

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:sha256:2457feb815b5a1ffedadd09d359a126ffee5d4b9e505b46b2bca1e50f4e04eba","contract":["atom.Nav is a non-zero Atom constant whose String() method returns \"nav\"","atom.Lookup([]byte(\"nav\")) resolves to atom.Nav and atom.String([]byte(\"nav\")) returns \"nav\"","Parsing a \u003cnav\u003e HTML element assigns atom.Nav to the parsed Node.DataAtom field"],"goal":"verify golang.org/x/net/html/atom.Nav in pkg:golang/golang.org/x/net@v0.0.0-20210525063256-abc453219eb5","kind":"HOW","packages":["pkg:golang/golang.org/x/net@v0.0.0-20210525063256-abc453219eb5"],"schemaVersion":1,"symbols":["golang.org/x/net/html/atom.Nav"]},"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@v0.0.0-20210525063256-abc453219eb5"],"schemaVersion":1,"subject":"pkg:golang/golang.org/x/net@v0.0.0-20210525063256-abc453219eb5","symbols":["golang.org/x/net/html/atom.Nav"],"verifierAdapter":"golang@1"}

module example.com/sample

go 1.26

require golang.org/x/net v0.0.0-20210525063256-abc453219eb5

golang.org/x/net v0.0.0-20210525063256-abc453219eb5 h1:wjuX4b5yYQnEQHzd+CBcrcC6OVR2J1CN6mUy0oSxIPo=
golang.org/x/net v0.0.0-20210525063256-abc453219eb5/go.mod h1:9nx3DQGgdP8bBQD5qxJ1jj9UTztislL4KSBs9R2vV5Y=

package main

import (
	"fmt"

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

func main() {
	tag := atom.Nav
	fmt.Printf("atom.Nav = %#x (%q)\n", uint32(tag), tag.String())
	fmt.Printf("atom.Lookup(\"nav\") == atom.Nav: %v\n", atom.Lookup([]byte("nav")) == atom.Nav)
}

{
  "schemaVersion": 1,
  "goal": "verify golang.org/x/net/html/atom.Nav in pkg:golang/golang.org/x/net@v0.0.0-20210525063256-abc453219eb5",
  "kind": "HOW",
  "packages": [
    "pkg:golang/golang.org/x/net@v0.0.0-20210525063256-abc453219eb5"
  ],
  "symbols": [
    "golang.org/x/net/html/atom.Nav"
  ]
}

package main

import (
	"fmt"
	"os"
	"strings"

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

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

func verifyAtomNav() error {
	// 1. atom.Nav is a non-zero Atom constant whose String() method returns "nav"
	if atom.Nav == 0 {
		return fmt.Errorf("atom.Nav is 0, want non-zero Atom")
	}
	if got := atom.Nav.String(); got != "nav" {
		return fmt.Errorf("atom.Nav.String() = %q, want \"nav\"", got)
	}

	// 2. atom.Lookup([]byte("nav")) resolves to atom.Nav and atom.String([]byte("nav")) returns "nav"
	if got := atom.Lookup([]byte("nav")); got != atom.Nav {
		return fmt.Errorf("atom.Lookup(\"nav\") = %v, want atom.Nav (%v)", got, atom.Nav)
	}
	if got := atom.String([]byte("nav")); got != atom.Nav.String() {
		return fmt.Errorf("atom.String(\"nav\") = %q, want %q", got, atom.Nav.String())
	}

	// 3. Parsing a <nav> HTML element assigns atom.Nav to the parsed Node.DataAtom field
	doc, err := html.Parse(strings.NewReader("<nav><a href=\"https://example.com\">Home</a></nav>"))
	if err != nil {
		return fmt.Errorf("html.Parse failed: %w", err)
	}
	var foundNav bool
	var walk func(*html.Node)
	walk = func(n *html.Node) {
		if n.Type == html.ElementNode && n.DataAtom == atom.Nav && n.Data == "nav" {
			foundNav = true
		}
		for c := n.FirstChild; c != nil; c = c.NextSibling {
			walk(c)
		}
	}
	walk(doc)
	if !foundNav {
		return fmt.Errorf("expected parsed <nav> element to have DataAtom == atom.Nav")
	}

	return nil
}