golang.org/x/net v0.0.0-20200324143707-d3edc9973b7e: html.DocumentNode

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.DocumentNode in pkg:golang/golang.org/x/net@v0.0.0-20200324143707-d3edc9973b7e
Kind: HOW

Use EXACTLY these public packages and versions:
  - pkg:golang/golang.org/x/net@v0.0.0-20200324143707-d3edc9973b7e
Demonstrate these symbols/APIs:
  - golang.org/x/net/html.DocumentNode

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:sha256:10c7e4199c84934427ea88fd75bfc8b0c026448da77d306100eea8dbda504cfb","contract":["html.Parse parses an HTML document and returns a root Node with Type equal to html.DocumentNode","A DocumentNode has a nil Parent and contains top-level DoctypeNode and ElementNode as children","html.Render serializes a tree rooted at a DocumentNode back to HTML"],"goal":"verify golang.org/x/net/html.DocumentNode in pkg:golang/golang.org/x/net@v0.0.0-20200324143707-d3edc9973b7e","kind":"HOW","packages":["pkg:golang/golang.org/x/net@v0.0.0-20200324143707-d3edc9973b7e"],"schemaVersion":1,"symbols":["golang.org/x/net/html.DocumentNode"]},"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@v0.0.0-20200324143707-d3edc9973b7e"],"schemaVersion":1,"subject":"pkg:golang/golang.org/x/net@v0.0.0-20200324143707-d3edc9973b7e","symbols":["golang.org/x/net/html.DocumentNode"],"verifierAdapter":"golang@1"}

module example.com/sample

go 1.21

require golang.org/x/net v0.0.0-20200324143707-d3edc9973b7e

golang.org/x/crypto v0.0.0-20190308221718-c2843e01d9a2/go.mod h1:djNgcEr1/C05ACkg1iLfiJU5Ep61QUkGW8qpdssI0+w=
golang.org/x/net v0.0.0-20200324143707-d3edc9973b7e h1:3G+cUijn7XD+S4eJFddp53Pv7+slrESplyjG25HgL+k=
golang.org/x/net v0.0.0-20200324143707-d3edc9973b7e/go.mod h1:qpuaurCH72eLCgpAm/N6yyVIVM9cpaDIP3A8BGJEC5A=
golang.org/x/sys v0.0.0-20190215142949-d0b11bdaac8a/go.mod h1:STP8DvDyc/dI5b8T5hshtkjS+E42TnysNCUPdjciGhY=
golang.org/x/sys v0.0.0-20200323222414-85ca7c5b95cd/go.mod h1:h1NjWce9XRLGQEsW7wpKNCjG9DtNlClVuFLEZdDNbEs=
golang.org/x/text v0.3.0/go.mod h1:NqM8EUOU14njkJ3fqMW+pc6Ldnwhi/IjpwHt7yyuwOQ=

package main

import (
	"fmt"
	"log"
	"strings"

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

func main() {
	rawHTML := `<!DOCTYPE html><html><head><title>Sample</title></head><body><h1>Document</h1></body></html>`

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

	if doc.Type == html.DocumentNode {
		fmt.Println("Parsed root node is a DocumentNode")
	}

	for child := doc.FirstChild; child != nil; child = child.NextSibling {
		switch child.Type {
		case html.DoctypeNode:
			fmt.Printf("Found Doctype child: %s\n", child.Data)
		case html.ElementNode:
			fmt.Printf("Found Element child: <%s>\n", child.Data)
		}
	}
}

{
  "schemaVersion": 1,
  "goal": "verify golang.org/x/net/html.DocumentNode in pkg:golang/golang.org/x/net@v0.0.0-20200324143707-d3edc9973b7e",
  "kind": "HOW",
  "packages": [
    "pkg:golang/golang.org/x/net@v0.0.0-20200324143707-d3edc9973b7e"
  ],
  "symbols": [
    "golang.org/x/net/html.DocumentNode"
  ]
}

package main

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

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

func main() {
	// Assertion 1: html.Parse parses an HTML document and returns a root Node with Type equal to html.DocumentNode
	rawHTML := `<!DOCTYPE html><html><head><title>Test</title></head><body><p>Hello World</p></body></html>`
	doc, err := html.Parse(strings.NewReader(rawHTML))
	if err != nil {
		fmt.Fprintf(os.Stderr, "assertion 1 failed: html.Parse returned error: %v\n", err)
		os.Exit(1)
	}
	if doc == nil {
		fmt.Fprintf(os.Stderr, "assertion 1 failed: doc is nil\n")
		os.Exit(1)
	}
	if doc.Type != html.DocumentNode {
		fmt.Fprintf(os.Stderr, "assertion 1 failed: expected Type %v (DocumentNode), got %v\n", html.DocumentNode, doc.Type)
		os.Exit(1)
	}
	if doc.Data != "" {
		fmt.Fprintf(os.Stderr, "assertion 1 failed: expected empty Data for DocumentNode, got %q\n", doc.Data)
		os.Exit(1)
	}

	// Assertion 2: A DocumentNode has a nil Parent and contains top-level DoctypeNode and ElementNode as children
	if doc.Parent != nil {
		fmt.Fprintf(os.Stderr, "assertion 2 failed: expected nil Parent for DocumentNode, got %v\n", doc.Parent)
		os.Exit(1)
	}

	doctypeChild := doc.FirstChild
	if doctypeChild == nil || doctypeChild.Type != html.DoctypeNode || doctypeChild.Data != "html" {
		fmt.Fprintf(os.Stderr, "assertion 2 failed: expected first child to be DoctypeNode with Data 'html', got %+v\n", doctypeChild)
		os.Exit(1)
	}
	if doctypeChild.Parent != doc {
		fmt.Fprintf(os.Stderr, "assertion 2 failed: expected doctype child Parent to point to DocumentNode\n")
		os.Exit(1)
	}

	htmlElemChild := doctypeChild.NextSibling
	if htmlElemChild == nil || htmlElemChild.Type != html.ElementNode || htmlElemChild.Data != "html" {
		fmt.Fprintf(os.Stderr, "assertion 2 failed: expected second child to be ElementNode <html>, got %+v\n", htmlElemChild)
		os.Exit(1)
	}
	if htmlElemChild.Parent != doc {
		fmt.Fprintf(os.Stderr, "assertion 2 failed: expected html elem child Parent to point to DocumentNode\n")
		os.Exit(1)
	}

	// Assertion 3: html.Render serializes a tree rooted at a DocumentNode back to HTML
	var buf bytes.Buffer
	if err := html.Render(&buf, doc); err != nil {
		fmt.Fprintf(os.Stderr, "assertion 3 failed: html.Render returned error: %v\n", err)
		os.Exit(1)
	}
	rendered := buf.String()
	expected := `<!DOCTYPE html><html><head><title>Test</title></head><body><p>Hello World</p></body></html>`
	if rendered != expected {
		fmt.Fprintf(os.Stderr, "assertion 3 failed: expected rendered HTML %q, got %q\n", expected, rendered)
		os.Exit(1)
	}

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