golang.org/x/net v0.24.0: html.Node

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.Node in pkg:golang/golang.org/x/net@v0.24.0
Kind: HOW

Use EXACTLY these public packages and versions:
  - pkg:golang/golang.org/x/net@v0.24.0
Demonstrate these symbols/APIs:
  - golang.org/x/net/html.Node

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:f47c18239a26d53f2facf7936fa1eb31d33bb7be9df5459d9b758bcb89f7a413","contract":["html.Node struct fields represent node type, data, and attributes","html.Node.AppendChild attaches child and sets FirstChild, LastChild, and Parent pointers","html.Node.AppendChild maintains sibling chain when appending multiple children","html.Node.InsertBefore inserts new child before reference node and updates sibling links","html.Node.RemoveChild detaches child and unlinks sibling pointers","html.Parse builds a valid DocumentNode tree with root node and child elements","html.Render serializes Node tree to HTML output matching node structure and attributes"],"goal":"verify golang.org/x/net/html.Node in pkg:golang/golang.org/x/net@v0.24.0","kind":"HOW","packages":["pkg:golang/golang.org/x/net@v0.24.0"],"schemaVersion":1,"symbols":["golang.org/x/net/html.Node"]},"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@v0.24.0"],"schemaVersion":1,"subject":"pkg:golang/golang.org/x/net@v0.24.0","symbols":["golang.org/x/net/html.Node"],"verifierAdapter":"golang@1"}

module example.com/sample

go 1.26.6

require golang.org/x/net v0.24.0

golang.org/x/net v0.24.0 h1:1PcaxkF854Fu3+lvBIx5SYn9wRlBzzcnHZSiaFFAb0w=
golang.org/x/net v0.24.0/go.mod h1:2Q7sJY5mzlzWjKtYUEXSlBWCdyaioyXzRB2RtU8KVE8=

package main

import (
	"bytes"
	"fmt"
	"strings"

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

func main() {
	// Construct an HTML node tree manually
	parent := &html.Node{
		Type:     html.ElementNode,
		DataAtom: atom.Div,
		Data:     "div",
		Attr: []html.Attribute{
			{Key: "id", Val: "content"},
			{Key: "class", Val: "container"},
		},
	}

	child := &html.Node{
		Type:     html.ElementNode,
		DataAtom: atom.P,
		Data:     "p",
	}

	text := &html.Node{
		Type: html.TextNode,
		Data: "Hello from html.Node sample!",
	}

	child.AppendChild(text)
	parent.AppendChild(child)

	var buf bytes.Buffer
	if err := html.Render(&buf, parent); err != nil {
		fmt.Printf("Render failed: %v\n", err)
		return
	}
	fmt.Printf("Rendered HTML:\n%s\n", buf.String())

	// Parse HTML snippet and inspect document tree
	raw := `<div class="greeting"><span>Welcome</span></div>`
	doc, err := html.Parse(strings.NewReader(raw))
	if err != nil {
		fmt.Printf("Parse failed: %v\n", err)
		return
	}

	fmt.Printf("Parsed root node type: %v, children: %v\n", doc.Type, doc.FirstChild != nil)
}

{
  "schemaVersion": 1,
  "goal": "verify golang.org/x/net/html.Node in pkg:golang/golang.org/x/net@v0.24.0",
  "kind": "HOW",
  "packages": [
    "pkg:golang/golang.org/x/net@v0.24.0"
  ],
  "symbols": [
    "golang.org/x/net/html.Node"
  ]
}

package main

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

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

func main() {
	// 1. html.Node struct fields represent node type, data, and attributes
	elem := &html.Node{
		Type: html.ElementNode,
		Data: "div",
		Attr: []html.Attribute{
			{Key: "id", Val: "main"},
			{Key: "class", Val: "content"},
		},
	}
	if elem.Type != html.ElementNode || elem.Data != "div" || len(elem.Attr) != 2 {
		fmt.Fprintf(os.Stderr, "Node fields mismatch\n")
		os.Exit(1)
	}
	if elem.Attr[0].Key != "id" || elem.Attr[0].Val != "main" || elem.Attr[1].Key != "class" || elem.Attr[1].Val != "content" {
		fmt.Fprintf(os.Stderr, "Node Attr mismatch\n")
		os.Exit(1)
	}

	// 2. html.Node.AppendChild attaches child and sets FirstChild, LastChild, and Parent pointers
	parent := &html.Node{Type: html.ElementNode, Data: "ul"}
	child1 := &html.Node{Type: html.ElementNode, Data: "li"}
	parent.AppendChild(child1)
	if parent.FirstChild != child1 || parent.LastChild != child1 || child1.Parent != parent {
		fmt.Fprintf(os.Stderr, "AppendChild single child pointers mismatch\n")
		os.Exit(1)
	}
	if child1.PrevSibling != nil || child1.NextSibling != nil {
		fmt.Fprintf(os.Stderr, "Single child should have nil siblings\n")
		os.Exit(1)
	}

	// 3. html.Node.AppendChild maintains sibling chain when appending multiple children
	child2 := &html.Node{Type: html.ElementNode, Data: "li"}
	parent.AppendChild(child2)
	if parent.FirstChild != child1 || parent.LastChild != child2 {
		fmt.Fprintf(os.Stderr, "AppendChild multiple children parent pointers mismatch\n")
		os.Exit(1)
	}
	if child1.NextSibling != child2 || child2.PrevSibling != child1 {
		fmt.Fprintf(os.Stderr, "AppendChild multiple children sibling pointers mismatch\n")
		os.Exit(1)
	}
	if child1.PrevSibling != nil || child2.NextSibling != nil {
		fmt.Fprintf(os.Stderr, "Sibling boundary pointers mismatch\n")
		os.Exit(1)
	}

	// 4. html.Node.InsertBefore inserts new child before reference node and updates sibling links
	childMiddle := &html.Node{Type: html.ElementNode, Data: "li"}
	parent.InsertBefore(childMiddle, child2)
	if child1.NextSibling != childMiddle || childMiddle.PrevSibling != child1 {
		fmt.Fprintf(os.Stderr, "InsertBefore middle prev links mismatch\n")
		os.Exit(1)
	}
	if childMiddle.NextSibling != child2 || child2.PrevSibling != childMiddle {
		fmt.Fprintf(os.Stderr, "InsertBefore middle next links mismatch\n")
		os.Exit(1)
	}
	if childMiddle.Parent != parent {
		fmt.Fprintf(os.Stderr, "InsertBefore parent link mismatch\n")
		os.Exit(1)
	}

	// 5. html.Node.RemoveChild detaches child and unlinks sibling pointers
	parent.RemoveChild(childMiddle)
	if childMiddle.Parent != nil || childMiddle.PrevSibling != nil || childMiddle.NextSibling != nil {
		fmt.Fprintf(os.Stderr, "RemoveChild did not clear detached node pointers\n")
		os.Exit(1)
	}
	if child1.NextSibling != child2 || child2.PrevSibling != child1 {
		fmt.Fprintf(os.Stderr, "RemoveChild did not restore sibling links\n")
		os.Exit(1)
	}

	// 6. html.Parse builds a valid DocumentNode tree with root node and child elements
	rawHTML := `<html><head><title>Test</title></head><body><p>Hello</p></body></html>`
	doc, err := html.Parse(strings.NewReader(rawHTML))
	if err != nil || doc == nil {
		fmt.Fprintf(os.Stderr, "html.Parse failed: %v\n", err)
		os.Exit(1)
	}
	if doc.Type != html.DocumentNode {
		fmt.Fprintf(os.Stderr, "Parsed root is not DocumentNode: got %v\n", doc.Type)
		os.Exit(1)
	}
	if doc.FirstChild == nil || doc.FirstChild.Data != "html" {
		fmt.Fprintf(os.Stderr, "Expected first child to be html node\n")
		os.Exit(1)
	}

	// 7. html.Render serializes Node tree to HTML output matching node structure and attributes
	div := &html.Node{
		Type: html.ElementNode,
		Data: "div",
		Attr: []html.Attribute{
			{Key: "class", Val: "box"},
		},
	}
	span := &html.Node{
		Type: html.ElementNode,
		Data: "span",
	}
	spanText := &html.Node{
		Type: html.TextNode,
		Data: "text",
	}
	span.AppendChild(spanText)
	div.AppendChild(span)

	var buf bytes.Buffer
	if err := html.Render(&buf, div); err != nil {
		fmt.Fprintf(os.Stderr, "html.Render failed: %v\n", err)
		os.Exit(1)
	}
	expected := `<div class="box"><span>text</span></div>`
	if buf.String() != expected {
		fmt.Fprintf(os.Stderr, "Render output mismatch: got %q, want %q\n", buf.String(), expected)
		os.Exit(1)
	}

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