golang.org/x/net v0.23.0: html.Parse, html.Render

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 Parse and Render in pkg:golang/golang.org/x/net@v0.23.0
Kind: HOW

Use EXACTLY these public packages and versions:
  - pkg:golang/golang.org/x/net@v0.23.0
Demonstrate these symbols/APIs:
  - golang.org/x/net/html.Parse
  - golang.org/x/net/html.Render

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:sha256:55b8e44e494e8c45be8b945c30a91fcef83af5711b441d3b5142474e632b5cc0","contract":["html.Parse parses an HTML document into a Node tree with correct hierarchy and attributes","html.Render serializes a Node tree back to valid HTML matching the DOM structure"],"goal":"verify golang.org/x/net/html Parse and Render in pkg:golang/golang.org/x/net@v0.23.0","kind":"HOW","packages":["pkg:golang/golang.org/x/net@v0.23.0"],"schemaVersion":1,"symbols":["golang.org/x/net/html.Parse","golang.org/x/net/html.Render"]},"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@v0.23.0"],"schemaVersion":1,"subject":"pkg:golang/golang.org/x/net@v0.23.0","symbols":["golang.org/x/net/html.Parse","golang.org/x/net/html.Render"],"verifierAdapter":"golang@1"}

module example.com/sample

go 1.23.0

require golang.org/x/net v0.23.0

golang.org/x/net v0.23.0 h1:7EYJ93RZ9vYSZAIb2x3lnuvqO5zneoD6IvWjuhfxjTs=
golang.org/x/net v0.23.0/go.mod h1:JKghWKKOSdJwpW2GEx0Ja7fmaKnMsbu+MWVZTokSYmg=

package main

import (
	"bytes"
	"fmt"
	"log"
	"strings"

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

func main() {
	rawHTML := `<!DOCTYPE html><html><head><title>Sample</title></head><body><div class="content"><p>Hello, CodeSampleX!</p></div></body></html>`

	doc, err := html.Parse(strings.NewReader(rawHTML))
	if err != nil {
		log.Fatalf("failed to parse HTML: %v", err)
	}

	var buf bytes.Buffer
	if err := html.Render(&buf, doc); err != nil {
		log.Fatalf("failed to render HTML: %v", err)
	}

	fmt.Println("Rendered HTML:")
	fmt.Println(buf.String())
}

{
  "schemaVersion": 1,
  "goal": "verify golang.org/x/net/html Parse and Render in pkg:golang/golang.org/x/net@v0.23.0",
  "kind": "HOW",
  "packages": [
    "pkg:golang/golang.org/x/net@v0.23.0"
  ],
  "symbols": [
    "golang.org/x/net/html.Parse",
    "golang.org/x/net/html.Render"
  ]
}

package main

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

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

func main() {
	// Assertion 1: html.Parse parses an HTML document into a Node tree with correct hierarchy and attributes
	{
		inputHTML := `<!DOCTYPE html><html><head><title>Test Title</title></head><body><div id="main" class="container"><p>Hello World</p><a href="https://example.com">Link</a></div></body></html>`
		doc, err := html.Parse(strings.NewReader(inputHTML))
		if err != nil {
			fmt.Fprintf(os.Stderr, "assertion 1 failed: html.Parse error: %v\n", err)
			os.Exit(1)
		}
		if doc.Type != html.DocumentNode {
			fmt.Fprintf(os.Stderr, "assertion 1 failed: expected root DocumentNode, got %v\n", doc.Type)
			os.Exit(1)
		}

		// Find div element and verify its attributes
		var foundDiv *html.Node
		var findDiv func(*html.Node)
		findDiv = func(n *html.Node) {
			if n.Type == html.ElementNode && n.Data == "div" {
				foundDiv = n
				return
			}
			for c := n.FirstChild; c != nil; c = c.NextSibling {
				findDiv(c)
			}
		}
		findDiv(doc)

		if foundDiv == nil {
			fmt.Fprintf(os.Stderr, "assertion 1 failed: div element not found\n")
			os.Exit(1)
		}

		var idVal, classVal string
		for _, attr := range foundDiv.Attr {
			if attr.Key == "id" {
				idVal = attr.Val
			} else if attr.Key == "class" {
				classVal = attr.Val
			}
		}
		if idVal != "main" || classVal != "container" {
			fmt.Fprintf(os.Stderr, "assertion 1 failed: unexpected attributes id=%q class=%q\n", idVal, classVal)
			os.Exit(1)
		}
	}

	// Assertion 2: html.Render serializes a Node tree back to valid HTML matching the DOM structure
	{
		// Create a synthetic node tree
		divNode := &html.Node{
			Type: html.ElementNode,
			Data: "div",
			Attr: []html.Attribute{
				{Key: "id", Val: "rendered-div"},
			},
		}
		spanNode := &html.Node{
			Type: html.ElementNode,
			Data: "span",
		}
		textNode := &html.Node{
			Type: html.TextNode,
			Data: "Rendered Text Content",
		}
		spanNode.AppendChild(textNode)
		divNode.AppendChild(spanNode)

		var buf bytes.Buffer
		err := html.Render(&buf, divNode)
		if err != nil {
			fmt.Fprintf(os.Stderr, "assertion 2 failed: html.Render error: %v\n", err)
			os.Exit(1)
		}

		rendered := buf.String()
		expected := `<div id="rendered-div"><span>Rendered Text Content</span></div>`
		if rendered != expected {
			fmt.Fprintf(os.Stderr, "assertion 2 failed: expected %q, got %q\n", expected, rendered)
			os.Exit(1)
		}
	}

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