golang.org/x/net v0.0.0-20191119073136-fc4aabc6c914: atom.H1

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/atom.H1 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/atom.H1

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:e5728bc97fc005a5b4d60dba35869759603a2804c87b5f9e7212039add098269","contract":["atom.H1 is a non-zero Atom constant whose String() method returns \"h1\"","atom.Lookup on byte slice \"h1\" returns atom.H1","atom.String on byte slice \"h1\" returns \"h1\"","atom.H1 is distinct from other heading atoms such as atom.H2 and atom.H3","html.Parse on HTML containing \u003ch1\u003e tag yields an ElementNode with DataAtom equal to atom.H1","explicitly created html.Node with DataAtom atom.H1 and Data \"h1\" renders as an \u003ch1\u003e element"],"goal":"verify golang.org/x/net/html/atom.H1 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/atom.H1"]},"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/atom.H1"],"verifierAdapter":"golang@1"}

module sample

go 1.21

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=

package main

import (
	"bytes"
	"fmt"
	"strings"

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

// IsH1Node checks whether n is an HTML <h1> element node.
func IsH1Node(n *html.Node) bool {
	return n != nil && n.Type == html.ElementNode && n.DataAtom == atom.H1
}

// NewH1Node constructs a new <h1> element node with text content.
func NewH1Node(text string) *html.Node {
	el := &html.Node{
		Type:     html.ElementNode,
		DataAtom: atom.H1,
		Data:     atom.H1.String(),
	}
	if text != "" {
		el.AppendChild(&html.Node{
			Type: html.TextNode,
			Data: text,
		})
	}
	return el
}

// FindH1 searches a DOM subtree for the first <h1> element node.
func FindH1(n *html.Node) *html.Node {
	if IsH1Node(n) {
		return n
	}
	for c := n.FirstChild; c != nil; c = c.NextSibling {
		if found := FindH1(c); found != nil {
			return found
		}
	}
	return nil
}

func main() {
	fmt.Printf("atom.H1 value: %d, name: %q\n", atom.H1, atom.H1.String())

	lookedUp := atom.Lookup([]byte("h1"))
	fmt.Printf("Lookup(\"h1\") == atom.H1: %v\n", lookedUp == atom.H1)

	h1 := NewH1Node("Example Heading")
	var buf bytes.Buffer
	if err := html.Render(&buf, h1); err != nil {
		panic(err)
	}
	fmt.Printf("Rendered: %s\n", buf.String())

	doc, err := html.Parse(strings.NewReader("<html><body><h1>Page Title</h1></body></html>"))
	if err != nil {
		panic(err)
	}
	if found := FindH1(doc); found != nil {
		fmt.Printf("Parsed <h1> element DataAtom matches atom.H1: %v\n", found.DataAtom == atom.H1)
	}
}

{
  "schemaVersion": 1,
  "goal": "verify golang.org/x/net/html/atom.H1 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/atom.H1"
  ]
}

package main

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

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

func main() {
	// 1. atom.H1 is a non-zero Atom constant whose String() method returns "h1"
	if atom.H1 == 0 {
		fmt.Fprintf(os.Stderr, "FAIL: expected atom.H1 to be non-zero\n")
		os.Exit(1)
	}
	if atom.H1.String() != "h1" {
		fmt.Fprintf(os.Stderr, "FAIL: expected atom.H1.String() == \"h1\", got %q\n", atom.H1.String())
		os.Exit(1)
	}

	// 2. atom.Lookup on byte slice "h1" returns atom.H1
	if got := atom.Lookup([]byte("h1")); got != atom.H1 {
		fmt.Fprintf(os.Stderr, "FAIL: expected atom.Lookup([]byte(\"h1\")) == atom.H1, got %v\n", got)
		os.Exit(1)
	}

	// 3. atom.String on byte slice "h1" returns "h1"
	if got := atom.String([]byte("h1")); got != "h1" {
		fmt.Fprintf(os.Stderr, "FAIL: expected atom.String([]byte(\"h1\")) == \"h1\", got %q\n", got)
		os.Exit(1)
	}

	// 4. atom.H1 is distinct from other heading atoms such as atom.H2 and atom.H3
	for _, other := range []atom.Atom{atom.H2, atom.H3, atom.H4, atom.H5, atom.H6} {
		if atom.H1 == other {
			fmt.Fprintf(os.Stderr, "FAIL: expected atom.H1 to be distinct from %v\n", other)
			os.Exit(1)
		}
	}

	// 5. html.Parse on HTML containing <h1> tag yields an ElementNode with DataAtom equal to atom.H1
	doc, err := html.Parse(strings.NewReader("<!DOCTYPE html><html><body><h1>Title</h1></body></html>"))
	if err != nil {
		fmt.Fprintf(os.Stderr, "FAIL: html.Parse failed: %v\n", err)
		os.Exit(1)
	}
	var h1Node *html.Node
	var walk func(*html.Node)
	walk = func(n *html.Node) {
		if n.Type == html.ElementNode && n.DataAtom == atom.H1 {
			h1Node = n
			return
		}
		for c := n.FirstChild; c != nil; c = c.NextSibling {
			walk(c)
		}
	}
	walk(doc)
	if h1Node == nil || h1Node.Data != "h1" {
		fmt.Fprintf(os.Stderr, "FAIL: expected parsed ElementNode with DataAtom == atom.H1 and Data == \"h1\"\n")
		os.Exit(1)
	}

	// 6. explicitly created html.Node with DataAtom atom.H1 and Data "h1" renders as an <h1> element
	node := &html.Node{
		Type:     html.ElementNode,
		DataAtom: atom.H1,
		Data:     atom.H1.String(),
	}
	node.AppendChild(&html.Node{
		Type: html.TextNode,
		Data: "Heading Text",
	})
	var buf bytes.Buffer
	if err := html.Render(&buf, node); err != nil {
		fmt.Fprintf(os.Stderr, "FAIL: html.Render failed: %v\n", err)
		os.Exit(1)
	}
	if buf.String() != "<h1>Heading Text</h1>" {
		fmt.Fprintf(os.Stderr, "FAIL: expected rendered \"<h1>Heading Text</h1>\", got %q\n", buf.String())
		os.Exit(1)
	}

	fmt.Println("PASS")
}