golang.org/x/net v0.47.0: 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.Render 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.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:c16e968b55f6ba35c8ab06bcd9e74029841756d7ae9e12645b81a4e2e5798f80","contract":["html.Render serializes a DOM tree into valid HTML matching the element hierarchy and attributes","html.Render escapes special HTML characters in text and attribute values","html.Render formats void elements with self-closing tag syntax","html.Render serializes comment and Doctype nodes with appropriate delimiters"],"goal":"verify golang.org/x/net/html.Render 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.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@v0.47.0"],"schemaVersion":1,"subject":"pkg:golang/golang.org/x/net@v0.47.0","symbols":["golang.org/x/net/html.Render"],"verifierAdapter":"golang@1"}

module sample

go 1.24.0

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 (
	"bytes"
	"fmt"
	"log"

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

func main() {
	doc := &html.Node{
		Type:     html.ElementNode,
		Data:     "div",
		DataAtom: atom.Div,
		Attr: []html.Attribute{
			{Key: "class", Val: "greeting"},
		},
	}
	text := &html.Node{
		Type: html.TextNode,
		Data: "Hello, World!",
	}
	doc.AppendChild(text)

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

	fmt.Println(buf.String())
}

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

package main

import (
	"bytes"
	"fmt"
	"os"

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

func main() {
	// Assertion 1: html.Render serializes a DOM tree into valid HTML matching the element hierarchy and attributes
	{
		div := &html.Node{
			Type:     html.ElementNode,
			Data:     "div",
			DataAtom: atom.Div,
			Attr: []html.Attribute{
				{Key: "id", Val: "content"},
				{Key: "class", Val: "main-box"},
			},
		}
		p := &html.Node{
			Type:     html.ElementNode,
			Data:     "p",
			DataAtom: atom.P,
		}
		text := &html.Node{
			Type: html.TextNode,
			Data: "Hello World",
		}
		p.AppendChild(text)
		div.AppendChild(p)

		var buf bytes.Buffer
		if err := html.Render(&buf, div); err != nil {
			fmt.Fprintf(os.Stderr, "assertion 1 failed: html.Render error: %v\n", err)
			os.Exit(1)
		}
		expected := `<div id="content" class="main-box"><p>Hello World</p></div>`
		if got := buf.String(); got != expected {
			fmt.Fprintf(os.Stderr, "assertion 1 failed: expected %q, got %q\n", expected, got)
			os.Exit(1)
		}
	}

	// Assertion 2: html.Render escapes special HTML characters in text and attribute values
	{
		link := &html.Node{
			Type:     html.ElementNode,
			Data:     "a",
			DataAtom: atom.A,
			Attr: []html.Attribute{
				{Key: "href", Val: "/search?q=a&b=c"},
			},
		}
		text := &html.Node{
			Type: html.TextNode,
			Data: "Tom & Jerry <friends>",
		}
		link.AppendChild(text)

		var buf bytes.Buffer
		if err := html.Render(&buf, link); err != nil {
			fmt.Fprintf(os.Stderr, "assertion 2 failed: html.Render error: %v\n", err)
			os.Exit(1)
		}
		expected := `<a href="/search?q=a&amp;b=c">Tom &amp; Jerry &lt;friends&gt;</a>`
		if got := buf.String(); got != expected {
			fmt.Fprintf(os.Stderr, "assertion 2 failed: expected %q, got %q\n", expected, got)
			os.Exit(1)
		}
	}

	// Assertion 3: html.Render formats void elements with self-closing tag syntax
	{
		img := &html.Node{
			Type:     html.ElementNode,
			Data:     "img",
			DataAtom: atom.Img,
			Attr: []html.Attribute{
				{Key: "src", Val: "image.png"},
				{Key: "alt", Val: "Sample"},
			},
		}

		var buf bytes.Buffer
		if err := html.Render(&buf, img); err != nil {
			fmt.Fprintf(os.Stderr, "assertion 3 failed: html.Render error: %v\n", err)
			os.Exit(1)
		}
		expected := `<img src="image.png" alt="Sample"/>`
		if got := buf.String(); got != expected {
			fmt.Fprintf(os.Stderr, "assertion 3 failed: expected %q, got %q\n", expected, got)
			os.Exit(1)
		}
	}

	// Assertion 4: html.Render serializes comment and Doctype nodes with appropriate delimiters
	{
		doc := &html.Node{
			Type: html.DocumentNode,
		}
		doctype := &html.Node{
			Type: html.DoctypeNode,
			Data: "html",
		}
		comment := &html.Node{
			Type: html.CommentNode,
			Data: " sample comment ",
		}
		doc.AppendChild(doctype)
		doc.AppendChild(comment)

		var buf bytes.Buffer
		if err := html.Render(&buf, doc); err != nil {
			fmt.Fprintf(os.Stderr, "assertion 4 failed: html.Render error: %v\n", err)
			os.Exit(1)
		}
		expected := "<!DOCTYPE html><!-- sample comment -->"
		if got := buf.String(); got != expected {
			fmt.Fprintf(os.Stderr, "assertion 4 failed: expected %q, got %q\n", expected, got)
			os.Exit(1)
		}
	}

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