golang.org/x/net v0.0.0-20180724234803-3673e40ba225: 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@v0.0.0-20180724234803-3673e40ba225
Kind: HOW

Use EXACTLY these public packages and versions:
  - pkg:golang/golang.org/x/net@v0.0.0-20180724234803-3673e40ba225
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:d941d290e17d099daf51c93cccdfc7af57fd529f66e93b4125b425c32a05f3f5","contract":["html.Render serializes nested element nodes and attributes into valid HTML","html.Render escapes special HTML characters in text nodes and attribute values","html.Render formats void elements without closing tags using self-closing syntax","html.Render serializes DoctypeNode and CommentNode alongside elements in a DocumentNode"],"goal":"verify golang.org/x/net/html.Render in pkg:golang/golang.org/x/net@v0.0.0-20180724234803-3673e40ba225","kind":"HOW","packages":["pkg:golang/golang.org/x/net@v0.0.0-20180724234803-3673e40ba225"],"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@v0.0.0-20180724234803-3673e40ba225"],"schemaVersion":1,"subject":"pkg:golang/golang.org/x/net@v0.0.0-20180724234803-3673e40ba225","symbols":["golang.org/x/net/html.Render"],"verifierAdapter":"golang@1"}

module sample

go 1.24.0

require golang.org/x/net v0.0.0-20180724234803-3673e40ba225

golang.org/x/net v0.0.0-20180724234803-3673e40ba225 h1:kNX+jCowfMYzvlSvJu5pQWEmyWFrBXJ3PBy10xKMXK8=
golang.org/x/net v0.0.0-20180724234803-3673e40ba225/go.mod h1:mL1N/T3taQHkDXs73rZJwtUhF3w3ftmwwsq0BUmARs4=

package main

import (
	"bytes"
	"fmt"
	"log"

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

func main() {
	article := &html.Node{
		Type:     html.ElementNode,
		Data:     "article",
		DataAtom: atom.Article,
		Attr: []html.Attribute{
			{Key: "data-role", Val: "card"},
		},
	}
	heading := &html.Node{
		Type:     html.ElementNode,
		Data:     "h1",
		DataAtom: atom.H1,
	}
	heading.AppendChild(&html.Node{
		Type: html.TextNode,
		Data: "Title & Overview",
	})
	article.AppendChild(heading)

	var out bytes.Buffer
	if err := html.Render(&out, article); err != nil {
		log.Fatalf("render failed: %v", err)
	}
	fmt.Println(out.String())
}

{
  "schemaVersion": 1,
  "goal": "verify golang.org/x/net/html.Render in pkg:golang/golang.org/x/net@v0.0.0-20180724234803-3673e40ba225",
  "kind": "HOW",
  "packages": [
    "pkg:golang/golang.org/x/net@v0.0.0-20180724234803-3673e40ba225"
  ],
  "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() {
	// 1. html.Render serializes nested element nodes and attributes into valid HTML
	{
		section := &html.Node{
			Type:     html.ElementNode,
			Data:     "section",
			DataAtom: atom.Section,
			Attr: []html.Attribute{
				{Key: "id", Val: "intro"},
				{Key: "class", Val: "panel"},
			},
		}
		span := &html.Node{
			Type:     html.ElementNode,
			Data:     "span",
			DataAtom: atom.Span,
		}
		span.AppendChild(&html.Node{
			Type: html.TextNode,
			Data: "Status OK",
		})
		section.AppendChild(span)

		var buf bytes.Buffer
		if err := html.Render(&buf, section); err != nil {
			fmt.Fprintf(os.Stderr, "check 1 failed: %v\n", err)
			os.Exit(1)
		}
		want := `<section id="intro" class="panel"><span>Status OK</span></section>`
		if got := buf.String(); got != want {
			fmt.Fprintf(os.Stderr, "check 1 mismatch: got %q, want %q\n", got, want)
			os.Exit(1)
		}
	}

	// 2. html.Render escapes special HTML characters in text nodes and attribute values
	{
		anchor := &html.Node{
			Type:     html.ElementNode,
			Data:     "a",
			DataAtom: atom.A,
			Attr: []html.Attribute{
				{Key: "href", Val: "http://example.com/?x=1&y=2"},
				{Key: "title", Val: `Say "hi"`},
			},
		}
		anchor.AppendChild(&html.Node{
			Type: html.TextNode,
			Data: "A < B & C > D",
		})

		var buf bytes.Buffer
		if err := html.Render(&buf, anchor); err != nil {
			fmt.Fprintf(os.Stderr, "check 2 failed: %v\n", err)
			os.Exit(1)
		}
		want := `<a href="http://example.com/?x=1&amp;y=2" title="Say &#34;hi&#34;">A &lt; B &amp; C &gt; D</a>`
		if got := buf.String(); got != want {
			fmt.Fprintf(os.Stderr, "check 2 mismatch: got %q, want %q\n", got, want)
			os.Exit(1)
		}
	}

	// 3. html.Render formats void elements without closing tags using self-closing syntax
	{
		br := &html.Node{
			Type:     html.ElementNode,
			Data:     "br",
			DataAtom: atom.Br,
		}
		input := &html.Node{
			Type:     html.ElementNode,
			Data:     "input",
			DataAtom: atom.Input,
			Attr: []html.Attribute{
				{Key: "type", Val: "text"},
				{Key: "name", Val: "field"},
			},
		}
		doc := &html.Node{Type: html.DocumentNode}
		doc.AppendChild(br)
		doc.AppendChild(input)

		var buf bytes.Buffer
		if err := html.Render(&buf, doc); err != nil {
			fmt.Fprintf(os.Stderr, "check 3 failed: %v\n", err)
			os.Exit(1)
		}
		want := `<br/><input type="text" name="field"/>`
		if got := buf.String(); got != want {
			fmt.Fprintf(os.Stderr, "check 3 mismatch: got %q, want %q\n", got, want)
			os.Exit(1)
		}
	}

	// 4. html.Render serializes DoctypeNode and CommentNode alongside elements in a DocumentNode
	{
		doc := &html.Node{Type: html.DocumentNode}
		doc.AppendChild(&html.Node{
			Type: html.DoctypeNode,
			Data: "html",
		})
		doc.AppendChild(&html.Node{
			Type: html.CommentNode,
			Data: "note",
		})
		p := &html.Node{
			Type:     html.ElementNode,
			Data:     "p",
			DataAtom: atom.P,
		}
		p.AppendChild(&html.Node{
			Type: html.TextNode,
			Data: "body",
		})
		doc.AppendChild(p)

		var buf bytes.Buffer
		if err := html.Render(&buf, doc); err != nil {
			fmt.Fprintf(os.Stderr, "check 4 failed: %v\n", err)
			os.Exit(1)
		}
		want := `<!DOCTYPE html><!--note--><p>body</p>`
		if got := buf.String(); got != want {
			fmt.Fprintf(os.Stderr, "check 4 mismatch: got %q, want %q\n", got, want)
			os.Exit(1)
		}
	}
}