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

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.Lookup 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.Lookup

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:sha256:2e4ad9f4bfef9b2b1e6883d27390e3a287b6d52f53a1a12f20a4c7536740b2e5","contract":["atom.Lookup resolves known tag \"div\" to atom.Div","atom.Lookup resolves known tag \"a\" to atom.A","atom.Lookup returns 0 for non-existent tag","atom.Lookup is case-sensitive and returns 0 for uppercase names","sample.LookupTagString resolves tag string \"span\" to atom.Span","sample.IsValidAtom returns true for valid atoms and false for unknown tags"],"goal":"verify golang.org/x/net/html/atom.Lookup 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.Lookup"]},"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.Lookup"],"verifierAdapter":"golang@1"}

module 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 sample

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

// LookupTag returns the atom.Atom corresponding to the provided byte slice.
func LookupTag(b []byte) atom.Atom {
	return atom.Lookup(b)
}

// LookupTagString returns the atom.Atom corresponding to the provided tag string.
func LookupTagString(s string) atom.Atom {
	return atom.Lookup([]byte(s))
}

// IsValidAtom reports whether the given byte slice maps to a known atom.
func IsValidAtom(b []byte) bool {
	return atom.Lookup(b) != 0
}

{
  "schemaVersion": 1,
  "goal": "verify golang.org/x/net/html/atom.Lookup 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.Lookup"
  ]
}

package main

import (
	"fmt"
	"os"

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

func main() {
	// Assertion 1: atom.Lookup resolves known tag "div" to atom.Div
	if got := atom.Lookup([]byte("div")); got != atom.Div {
		fmt.Fprintf(os.Stderr, "expected atom.Lookup(\"div\") == atom.Div, got %v\n", got)
		os.Exit(1)
	}

	// Assertion 2: atom.Lookup resolves known tag "a" to atom.A
	if got := atom.Lookup([]byte("a")); got != atom.A {
		fmt.Fprintf(os.Stderr, "expected atom.Lookup(\"a\") == atom.A, got %v\n", got)
		os.Exit(1)
	}

	// Assertion 3: atom.Lookup returns 0 for non-existent tag
	if got := atom.Lookup([]byte("not-an-html-atom")); got != 0 {
		fmt.Fprintf(os.Stderr, "expected atom.Lookup(\"not-an-html-atom\") == 0, got %v\n", got)
		os.Exit(1)
	}

	// Assertion 4: atom.Lookup is case-sensitive and returns 0 for uppercase names
	if got := atom.Lookup([]byte("DIV")); got != 0 {
		fmt.Fprintf(os.Stderr, "expected atom.Lookup(\"DIV\") == 0, got %v\n", got)
		os.Exit(1)
	}

	// Assertion 5: sample.LookupTagString resolves tag string "span" to atom.Span
	if got := sample.LookupTagString("span"); got != atom.Span {
		fmt.Fprintf(os.Stderr, "expected sample.LookupTagString(\"span\") == atom.Span, got %v\n", got)
		os.Exit(1)
	}

	// Assertion 6: sample.IsValidAtom returns true for valid atoms and false for unknown tags
	if !sample.IsValidAtom([]byte("body")) {
		fmt.Fprintf(os.Stderr, "expected sample.IsValidAtom(\"body\") to be true\n")
		os.Exit(1)
	}
	if sample.IsValidAtom([]byte("custom-element")) {
		fmt.Fprintf(os.Stderr, "expected sample.IsValidAtom(\"custom-element\") to be false\n")
		os.Exit(1)
	}

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