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

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.Parse 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.Parse

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:bee71365523c2675f4313516047e3a66bf271e9c7b28470b62d0257bd23cb813","contract":["html.Parse parses an HTML document into a DocumentNode tree with html, head, and body elements","html.Parse preserves element tag names, attributes, and nested text child nodes"],"goal":"verify golang.org/x/net/html.Parse 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.Parse"]},"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.Parse"],"verifierAdapter":"golang@1"}

module example.com/sample

go 1.22

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() {
	markup := `<!DOCTYPE html><html><head><title>Example</title></head><body><section id="main"><p class="lead">Hello HTML</p></section></body></html>`

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

	var walk func(*html.Node)
	walk = func(n *html.Node) {
		if n.Type == html.ElementNode && n.Data == "p" {
			for _, a := range n.Attr {
				if a.Key == "class" {
					fmt.Printf("paragraph class=%s\n", a.Val)
				}
			}
			if n.FirstChild != nil && n.FirstChild.Type == html.TextNode {
				fmt.Printf("paragraph text=%s\n", n.FirstChild.Data)
			}
		}
		for c := n.FirstChild; c != nil; c = c.NextSibling {
			walk(c)
		}
	}

	walk(doc)
}

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

package main

import (
	"fmt"
	"os"
	"strings"

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

func main() {
	markup := `<!DOCTYPE html><html><head><title>Example</title></head><body><section id="main"><p class="lead">Hello HTML</p></section></body></html>`

	// Assertion 1: html.Parse parses an HTML document into a DocumentNode tree with html, head, and body elements
	doc, err := html.Parse(strings.NewReader(markup))
	if err != nil {
		fmt.Fprintf(os.Stderr, "assertion 1 failed: html.Parse error: %v\n", err)
		os.Exit(1)
	}
	if doc == nil || doc.Type != html.DocumentNode {
		fmt.Fprintf(os.Stderr, "assertion 1 failed: expected DocumentNode root\n")
		os.Exit(1)
	}

	var findAtom func(*html.Node, atom.Atom) *html.Node
	findAtom = func(n *html.Node, target atom.Atom) *html.Node {
		if n == nil {
			return nil
		}
		if n.DataAtom == target {
			return n
		}
		for c := n.FirstChild; c != nil; c = c.NextSibling {
			if found := findAtom(c, target); found != nil {
				return found
			}
		}
		return nil
	}

	if findAtom(doc, atom.Html) == nil || findAtom(doc, atom.Head) == nil || findAtom(doc, atom.Body) == nil {
		fmt.Fprintf(os.Stderr, "assertion 1 failed: missing html, head, or body element\n")
		os.Exit(1)
	}

	// Assertion 2: html.Parse preserves element tag names, attributes, and nested text child nodes
	pNode := findAtom(doc, atom.P)
	if pNode == nil || pNode.Type != html.ElementNode || pNode.Data != "p" {
		fmt.Fprintf(os.Stderr, "assertion 2 failed: expected <p> ElementNode\n")
		os.Exit(1)
	}

	var classAttr string
	for _, a := range pNode.Attr {
		if a.Key == "class" {
			classAttr = a.Val
		}
	}
	if classAttr != "lead" {
		fmt.Fprintf(os.Stderr, "assertion 2 failed: expected class='lead', got %q\n", classAttr)
		os.Exit(1)
	}

	if pNode.FirstChild == nil || pNode.FirstChild.Type != html.TextNode || pNode.FirstChild.Data != "Hello HTML" {
		fmt.Fprintf(os.Stderr, "assertion 2 failed: expected text child 'Hello HTML'\n")
		os.Exit(1)
	}

	fmt.Println("Contract passed")
}