golang.org/x/net v0.20.0

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 pkg:golang/golang.org/x/net@v0.20.0
Kind: HOW

Use EXACTLY these public packages and versions:
  - pkg:golang/golang.org/x/net@v0.20.0

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:sha256:6150d3af6e398e40d3041af666a10aecf8e03f579638711b72b1258713b44dd7","contract":["html.Parse parses an HTML document into a Node tree with root Type equal to html.DocumentNode","html.Render serializes a parsed html.Node tree back to HTML matching the original document structure","html.EscapeString escapes special characters like ampersands, angle brackets, and quotes"],"goal":"verify pkg:golang/golang.org/x/net@v0.20.0","kind":"HOW","packages":["pkg:golang/golang.org/x/net@v0.20.0"],"schemaVersion":1},"contractCommand":["go","run","./test"],"environment":{"arch":"x64","distro":"ubuntu","ecosystem":"golang","language":"go","libc":"glibc","libcVersion":"2.39","os":"linux","osVersionBucket":"24","packageManager":"go","packageManagerVersion":"1.26.6","runtime":"go","runtimeVersion":"1.26.6","schemaVersion":1},"license":"MIT-0","packages":["pkg:golang/golang.org/x/net@v0.20.0"],"schemaVersion":1,"subject":"pkg:golang/golang.org/x/net@v0.20.0","verifierAdapter":"golang@1"}

module example.com/sample

go 1.26.0

require golang.org/x/net v0.20.0

golang.org/x/net v0.20.0 h1:aCL9BSgETF1k+blQaYUBx9hJ9LOGP3gAVemcZlf1Kpo=
golang.org/x/net v0.20.0/go.mod h1:z8BVo6PvndSri0LbOE3hAn0apkU+1YvI6E70E9jsnvY=

package main

import (
	"bytes"
	"fmt"
	"log"
	"strings"

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

func main() {
	rawHTML := `<!DOCTYPE html><html><head><title>CodeSampleX Demo</title></head><body><h1>Hello from golang.org/x/net</h1><p>Sample test document.</p></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 document root node successfully")
	}

	var buf bytes.Buffer
	if err := html.Render(&buf, doc); err != nil {
		log.Fatalf("failed to render HTML: %v", err)
	}

	fmt.Printf("Rendered HTML (%d bytes)\n", buf.Len())
}

{
  "schemaVersion": 1,
  "goal": "verify pkg:golang/golang.org/x/net@v0.20.0",
  "kind": "HOW",
  "packages": [
    "pkg:golang/golang.org/x/net@v0.20.0"
  ]
}

package main

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

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

func main() {
	// Assertion 1: html.Parse parses an HTML document into a Node tree with root Type equal to html.DocumentNode
	rawHTML := `<!DOCTYPE html><html><head><title>Test Document</title></head><body><h1>Heading</h1><p>Paragraph content</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)
	}

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

	htmlChild := doctypeChild.NextSibling
	if htmlChild == nil || htmlChild.Type != html.ElementNode || htmlChild.Data != "html" {
		fmt.Fprintf(os.Stderr, "assertion 1 failed: expected second child to be ElementNode with Data 'html'\n")
		os.Exit(1)
	}

	// Assertion 2: html.Render serializes a parsed html.Node tree back to HTML matching the original document structure
	var buf bytes.Buffer
	if err := html.Render(&buf, doc); err != nil {
		fmt.Fprintf(os.Stderr, "assertion 2 failed: html.Render returned error: %v\n", err)
		os.Exit(1)
	}
	rendered := buf.String()
	if rendered != rawHTML {
		fmt.Fprintf(os.Stderr, "assertion 2 failed: expected %q, got %q\n", rawHTML, rendered)
		os.Exit(1)
	}

	// Assertion 3: html.EscapeString escapes special characters like ampersands, angle brackets, and quotes
	plainText := `<script>alert("hello & welcome")</script>`
	escaped := html.EscapeString(plainText)
	expectedEscaped := `&lt;script&gt;alert(&#34;hello &amp; welcome&#34;)&lt;/script&gt;`
	if escaped != expectedEscaped {
		fmt.Fprintf(os.Stderr, "assertion 3 failed: expected %q, got %q\n", expectedEscaped, escaped)
		os.Exit(1)
	}
	unescaped := html.UnescapeString(escaped)
	if unescaped != plainText {
		fmt.Fprintf(os.Stderr, "assertion 3 failed: unescaping did not restore original text: got %q\n", unescaped)
		os.Exit(1)
	}

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