golang.org/x/net v0.0.0-20210525063256-abc453219eb5: 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@v0.0.0-20210525063256-abc453219eb5
Kind: HOW

Use EXACTLY these public packages and versions:
  - pkg:golang/golang.org/x/net@v0.0.0-20210525063256-abc453219eb5
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:sha256:4d4a518e63feb2e9c08d4ef1117d9323fbb77e631ac2e9bd7ce2209ef00edd41","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@v0.0.0-20210525063256-abc453219eb5","kind":"HOW","packages":["pkg:golang/golang.org/x/net@v0.0.0-20210525063256-abc453219eb5"],"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@v0.0.0-20210525063256-abc453219eb5"],"schemaVersion":1,"subject":"pkg:golang/golang.org/x/net@v0.0.0-20210525063256-abc453219eb5","symbols":["golang.org/x/net/html.Render"],"verifierAdapter":"golang@1"}

module sample

go 1.24.0

require golang.org/x/net v0.0.0-20210525063256-abc453219eb5

golang.org/x/net v0.0.0-20210525063256-abc453219eb5 h1:wjuX4b5yYQnEQHzd+CBcrcC6OVR2J1CN6mUy0oSxIPo=
golang.org/x/net v0.0.0-20210525063256-abc453219eb5/go.mod h1:9nx3DQGgdP8bBQD5qxJ1jj9UTztislL4KSBs9R2vV5Y=

package main

import (
	"bytes"
	"fmt"
	"log"

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

func main() {
	nav := &html.Node{
		Type:     html.ElementNode,
		Data:     "nav",
		DataAtom: atom.Nav,
		Attr: []html.Attribute{
			{Key: "aria-label", Val: "primary"},
		},
	}
	link := &html.Node{
		Type:     html.ElementNode,
		Data:     "a",
		DataAtom: atom.A,
		Attr: []html.Attribute{
			{Key: "href", Val: "https://example.com/docs"},
		},
	}
	link.AppendChild(&html.Node{
		Type: html.TextNode,
		Data: "Docs & Guides",
	})
	nav.AppendChild(link)

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

{
  "schemaVersion": 1,
  "goal": "verify golang.org/x/net/html.Render in pkg:golang/golang.org/x/net@v0.0.0-20210525063256-abc453219eb5",
  "kind": "HOW",
  "packages": [
    "pkg:golang/golang.org/x/net@v0.0.0-20210525063256-abc453219eb5"
  ],
  "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
	{
		div := &html.Node{
			Type:     html.ElementNode,
			Data:     "div",
			DataAtom: atom.Div,
			Attr: []html.Attribute{
				{Key: "id", Val: "box"},
				{Key: "class", Val: "container"},
			},
		}
		em := &html.Node{
			Type:     html.ElementNode,
			Data:     "em",
			DataAtom: atom.Em,
		}
		em.AppendChild(&html.Node{
			Type: html.TextNode,
			Data: "Ready",
		})
		div.AppendChild(em)

		var buf bytes.Buffer
		if err := html.Render(&buf, div); err != nil {
			fmt.Fprintf(os.Stderr, "assertion 1 error: %v\n", err)
			os.Exit(1)
		}
		want := `<div id="box" class="container"><em>Ready</em></div>`
		if got := buf.String(); got != want {
			fmt.Fprintf(os.Stderr, "assertion 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
	{
		span := &html.Node{
			Type:     html.ElementNode,
			Data:     "span",
			DataAtom: atom.Span,
			Attr: []html.Attribute{
				{Key: "data-query", Val: "a=1&b=2"},
				{Key: "title", Val: `quote "here"`},
			},
		}
		span.AppendChild(&html.Node{
			Type: html.TextNode,
			Data: "1 < 2 & 3 > 0",
		})

		var buf bytes.Buffer
		if err := html.Render(&buf, span); err != nil {
			fmt.Fprintf(os.Stderr, "assertion 2 error: %v\n", err)
			os.Exit(1)
		}
		want := `<span data-query="a=1&amp;b=2" title="quote &#34;here&#34;">1 &lt; 2 &amp; 3 &gt; 0</span>`
		if got := buf.String(); got != want {
			fmt.Fprintf(os.Stderr, "assertion 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
	{
		hr := &html.Node{
			Type:     html.ElementNode,
			Data:     "hr",
			DataAtom: atom.Hr,
		}
		img := &html.Node{
			Type:     html.ElementNode,
			Data:     "img",
			DataAtom: atom.Img,
			Attr: []html.Attribute{
				{Key: "src", Val: "https://example.com/icon.png"},
				{Key: "alt", Val: "icon"},
			},
		}
		doc := &html.Node{Type: html.DocumentNode}
		doc.AppendChild(hr)
		doc.AppendChild(img)

		var buf bytes.Buffer
		if err := html.Render(&buf, doc); err != nil {
			fmt.Fprintf(os.Stderr, "assertion 3 error: %v\n", err)
			os.Exit(1)
		}
		want := `<hr/><img src="https://example.com/icon.png" alt="icon"/>`
		if got := buf.String(); got != want {
			fmt.Fprintf(os.Stderr, "assertion 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: "header",
		})
		p := &html.Node{
			Type:     html.ElementNode,
			Data:     "p",
			DataAtom: atom.P,
		}
		p.AppendChild(&html.Node{
			Type: html.TextNode,
			Data: "content",
		})
		doc.AppendChild(p)

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