golang.org/x/net v0.0.0-20191119073136-fc4aabc6c914: html.DoctypeNode

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.DoctypeNode in pkg:golang/golang.org/x/net@v0.0.0-20191119073136-fc4aabc6c914
Kind: HOW

Use EXACTLY these public packages and versions:
  - pkg:golang/golang.org/x/net@v0.0.0-20191119073136-fc4aabc6c914
Demonstrate these symbols/APIs:
  - golang.org/x/net/html.DoctypeNode

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:e8da1a01402022d63ea816b7d6d869d64659661487f55cfc2f71738a515ceda1","contract":["html.DoctypeNode is a distinct html.NodeType constant","html.Parse parses \u003c!DOCTYPE html\u003e into a child node with Type == html.DoctypeNode and Data == \"html\"","html.Parse extracts the system identifier into Attr on an html.DoctypeNode","html.Render serializes an html.DoctypeNode into valid \u003c!DOCTYPE ...\u003e markup"],"goal":"verify golang.org/x/net/html.DoctypeNode in pkg:golang/golang.org/x/net@v0.0.0-20191119073136-fc4aabc6c914","kind":"HOW","packages":["pkg:golang/golang.org/x/net@v0.0.0-20191119073136-fc4aabc6c914"],"schemaVersion":1,"symbols":["golang.org/x/net/html.DoctypeNode"]},"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@v0.0.0-20191119073136-fc4aabc6c914"],"schemaVersion":1,"subject":"pkg:golang/golang.org/x/net@v0.0.0-20191119073136-fc4aabc6c914","symbols":["golang.org/x/net/html.DoctypeNode"],"verifierAdapter":"golang@1"}

package sample

import (
	"bytes"

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

// ExtractDoctype scans direct children of the root node and returns the first html.DoctypeNode.
func ExtractDoctype(root *html.Node) *html.Node {
	if root == nil {
		return nil
	}
	for n := root.FirstChild; n != nil; n = n.NextSibling {
		if n.Type == html.DoctypeNode {
			return n
		}
	}
	return nil
}

// IsDoctypeNode checks whether the provided node is non-nil and has Type html.DoctypeNode.
func IsDoctypeNode(n *html.Node) bool {
	return n != nil && n.Type == html.DoctypeNode
}

// CreateDoctypeNode constructs an html.Node with Type html.DoctypeNode and optional public/system identifiers.
func CreateDoctypeNode(name, publicID, systemID string) *html.Node {
	node := &html.Node{
		Type: html.DoctypeNode,
		Data: name,
	}
	if publicID != "" {
		node.Attr = append(node.Attr, html.Attribute{Key: "public", Val: publicID})
	}
	if systemID != "" {
		node.Attr = append(node.Attr, html.Attribute{Key: "system", Val: systemID})
	}
	return node
}

// FormatDoctype renders an html.Node into its serialized HTML string.
func FormatDoctype(n *html.Node) (string, error) {
	var buf bytes.Buffer
	if err := html.Render(&buf, n); err != nil {
		return "", err
	}
	return buf.String(), nil
}

module sample

go 1.26

require golang.org/x/net v0.0.0-20191119073136-fc4aabc6c914

golang.org/x/crypto v0.0.0-20190308221718-c2843e01d9a2/go.mod h1:djNgcEr1/C05ACkg1iLfiJU5Ep61QUkGW8qpdssI0+w=
golang.org/x/net v0.0.0-20191119073136-fc4aabc6c914 h1:MlY3mEfbnWGmUi4rtHOtNnnnN4UJRGSyLPx+DXA5Sq4=
golang.org/x/net v0.0.0-20191119073136-fc4aabc6c914/go.mod h1:z5CRVTTTmAJ677TzLLGU+0bjPO0LkuOLi4/5GtJWs/s=
golang.org/x/sys v0.0.0-20190215142949-d0b11bdaac8a/go.mod h1:STP8DvDyc/dI5b8T5hshtkjS+E42TnysNCUPdjciGhY=
golang.org/x/text v0.3.0/go.mod h1:NqM8EUOU14njkJ3fqMW+pc6Ldnwhi/IjpwHt7yyuwOQ=

{
  "schemaVersion": 1,
  "goal": "verify golang.org/x/net/html.DoctypeNode in pkg:golang/golang.org/x/net@v0.0.0-20191119073136-fc4aabc6c914",
  "kind": "HOW",
  "packages": [
    "pkg:golang/golang.org/x/net@v0.0.0-20191119073136-fc4aabc6c914"
  ],
  "symbols": [
    "golang.org/x/net/html.DoctypeNode"
  ]
}

package main

import (
	"fmt"
	"os"
	"strings"

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

func main() {
	// 1. Verify html.DoctypeNode is a valid html.NodeType constant and distinct from other node types.
	var dtType html.NodeType = html.DoctypeNode
	if dtType == html.ErrorNode ||
		dtType == html.TextNode ||
		dtType == html.DocumentNode ||
		dtType == html.ElementNode ||
		dtType == html.CommentNode {
		fmt.Fprintf(os.Stderr, "expected html.DoctypeNode to be distinct from other NodeType constants\n")
		os.Exit(1)
	}

	// 2. Verify html.Parse produces an html.DoctypeNode for standard HTML5 DOCTYPE.
	doc, err := html.Parse(strings.NewReader("<!DOCTYPE html><html><head><title>T</title></head><body></body></html>"))
	if err != nil {
		fmt.Fprintf(os.Stderr, "unexpected parse error: %v\n", err)
		os.Exit(1)
	}
	dt := sample.ExtractDoctype(doc)
	if dt == nil {
		fmt.Fprintf(os.Stderr, "expected a DoctypeNode child in parsed document\n")
		os.Exit(1)
	}
	if dt.Type != html.DoctypeNode || !sample.IsDoctypeNode(dt) {
		fmt.Fprintf(os.Stderr, "expected node Type to be html.DoctypeNode, got %v\n", dt.Type)
		os.Exit(1)
	}
	if dt.Data != "html" {
		fmt.Fprintf(os.Stderr, "expected DoctypeNode Data to be 'html', got %q\n", dt.Data)
		os.Exit(1)
	}

	// 3. Verify html.Parse populates public and system attributes on html.DoctypeNode.
	docSys, err := html.Parse(strings.NewReader(`<!DOCTYPE html SYSTEM "about:legacy-compat"><html><body></body></html>`))
	if err != nil {
		fmt.Fprintf(os.Stderr, "unexpected parse error for system doctype: %v\n", err)
		os.Exit(1)
	}
	dtSys := sample.ExtractDoctype(docSys)
	if dtSys == nil || dtSys.Type != html.DoctypeNode {
		fmt.Fprintf(os.Stderr, "expected DoctypeNode for system doctype\n")
		os.Exit(1)
	}
	hasSystemAttr := false
	for _, a := range dtSys.Attr {
		if a.Key == "system" && a.Val == "about:legacy-compat" {
			hasSystemAttr = true
		}
	}
	if !hasSystemAttr {
		fmt.Fprintf(os.Stderr, "expected system attribute 'about:legacy-compat' on DoctypeNode\n")
		os.Exit(1)
	}

	// 4. Verify html.Render serializes a manually constructed html.DoctypeNode accurately.
	node := sample.CreateDoctypeNode("html", "", "")
	rendered, err := sample.FormatDoctype(node)
	if err != nil {
		fmt.Fprintf(os.Stderr, "unexpected render error: %v\n", err)
		os.Exit(1)
	}
	if rendered != "<!DOCTYPE html>" {
		fmt.Fprintf(os.Stderr, "expected '<!DOCTYPE html>', got %q\n", rendered)
		os.Exit(1)
	}

	nodeSys := sample.CreateDoctypeNode("html", "", "about:legacy-compat")
	renderedSys, err := sample.FormatDoctype(nodeSys)
	if err != nil {
		fmt.Fprintf(os.Stderr, "unexpected render error with system ID: %v\n", err)
		os.Exit(1)
	}
	if renderedSys != `<!DOCTYPE html SYSTEM "about:legacy-compat">` {
		fmt.Fprintf(os.Stderr, "expected system doctype output, got %q\n", renderedSys)
		os.Exit(1)
	}

	fmt.Println("contract ok")
}