golang.org/x/net v0.0.0-20190813141303-74dc4d7220e7: html.NodeType

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.NodeType in pkg:golang/golang.org/x/net@v0.0.0-20190813141303-74dc4d7220e7
Kind: HOW

Use EXACTLY these public packages and versions:
  - pkg:golang/golang.org/x/net@v0.0.0-20190813141303-74dc4d7220e7
Demonstrate these symbols/APIs:
  - golang.org/x/net/html.NodeType

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:da01f1401d314a89efcd8fd4df7cea53945435484ac023bdf58f00a47d9ea03d","contract":["html.NodeType constants identify distinct DOM node kinds including ErrorNode, TextNode, DocumentNode, ElementNode, CommentNode, and DoctypeNode","html.Parse assigns the appropriate html.NodeType to each node in the parsed tree","Manually constructed html.Node instances preserve their html.NodeType across tree attachment"],"goal":"verify golang.org/x/net/html.NodeType in pkg:golang/golang.org/x/net@v0.0.0-20190813141303-74dc4d7220e7","kind":"HOW","packages":["pkg:golang/golang.org/x/net@v0.0.0-20190813141303-74dc4d7220e7"],"schemaVersion":1,"symbols":["golang.org/x/net/html.NodeType"]},"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@v0.0.0-20190813141303-74dc4d7220e7"],"schemaVersion":1,"subject":"pkg:golang/golang.org/x/net@v0.0.0-20190813141303-74dc4d7220e7","symbols":["golang.org/x/net/html.NodeType"],"verifierAdapter":"golang@1"}

module example.com/sample

go 1.24.0

require golang.org/x/net v0.0.0-20190813141303-74dc4d7220e7

golang.org/x/crypto v0.0.0-20190308221718-c2843e01d9a2/go.mod h1:djNgcEr1/C05ACkg1iLfiJU5Ep61QUkGW8qpdssI0+w=
golang.org/x/net v0.0.0-20190813141303-74dc4d7220e7 h1:fHDIZ2oxGnUZRN6WgWFCbYBjH9uqVPRCUVUDhs0wnbA=
golang.org/x/net v0.0.0-20190813141303-74dc4d7220e7/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 (
	"fmt"
	"log"
	"strings"

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

// FormatNodeType maps an html.NodeType to its canonical name.
func FormatNodeType(nt html.NodeType) string {
	switch nt {
	case html.ErrorNode:
		return "ErrorNode"
	case html.TextNode:
		return "TextNode"
	case html.DocumentNode:
		return "DocumentNode"
	case html.ElementNode:
		return "ElementNode"
	case html.CommentNode:
		return "CommentNode"
	case html.DoctypeNode:
		return "DoctypeNode"
	default:
		return fmt.Sprintf("NodeType(%d)", nt)
	}
}

// CountNodeTypes traverses an HTML tree and counts nodes by html.NodeType.
func CountNodeTypes(root *html.Node) map[html.NodeType]int {
	counts := make(map[html.NodeType]int)
	var visit func(*html.Node)
	visit = func(n *html.Node) {
		if n == nil {
			return
		}
		counts[n.Type]++
		for c := n.FirstChild; c != nil; c = c.NextSibling {
			visit(c)
		}
	}
	visit(root)
	return counts
}

func main() {
	src := `<!DOCTYPE html><html><!-- comment --><body><p>Sample</p></body></html>`
	doc, err := html.Parse(strings.NewReader(src))
	if err != nil {
		log.Fatalf("html.Parse failed: %v", err)
	}

	counts := CountNodeTypes(doc)
	fmt.Printf("Root type: %s\n", FormatNodeType(doc.Type))
	for nt, count := range counts {
		fmt.Printf("%s: %d\n", FormatNodeType(nt), count)
	}
}

{
  "schemaVersion": 1,
  "goal": "verify golang.org/x/net/html.NodeType in pkg:golang/golang.org/x/net@v0.0.0-20190813141303-74dc4d7220e7",
  "kind": "HOW",
  "packages": [
    "pkg:golang/golang.org/x/net@v0.0.0-20190813141303-74dc4d7220e7"
  ],
  "symbols": [
    "golang.org/x/net/html.NodeType"
  ]
}

package main

import (
	"fmt"
	"os"
	"strings"

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

func main() {
	// Assertion 1: html.NodeType constants identify distinct DOM node kinds including ErrorNode, TextNode, DocumentNode, ElementNode, CommentNode, and DoctypeNode
	expectedValues := map[html.NodeType]uint32{
		html.ErrorNode:    0,
		html.TextNode:     1,
		html.DocumentNode: 2,
		html.ElementNode:  3,
		html.CommentNode:  4,
		html.DoctypeNode:  5,
	}
	for nt, want := range expectedValues {
		if uint32(nt) != want {
			fmt.Fprintf(os.Stderr, "assertion 1 failed: expected NodeType %d to equal %d, got %d\n", nt, want, uint32(nt))
			os.Exit(1)
		}
	}

	nodeTypes := []html.NodeType{
		html.ErrorNode,
		html.TextNode,
		html.DocumentNode,
		html.ElementNode,
		html.CommentNode,
		html.DoctypeNode,
	}
	seen := make(map[html.NodeType]bool)
	for _, nt := range nodeTypes {
		if seen[nt] {
			fmt.Fprintf(os.Stderr, "assertion 1 failed: duplicate NodeType value %v\n", nt)
			os.Exit(1)
		}
		seen[nt] = true
	}

	// Assertion 2: html.Parse assigns the appropriate html.NodeType to each node in the parsed tree
	markup := `<!DOCTYPE html><html><!-- note --><body><article>Content</article></body></html>`
	doc, err := html.Parse(strings.NewReader(markup))
	if err != nil {
		fmt.Fprintf(os.Stderr, "assertion 2 failed: html.Parse returned error: %v\n", err)
		os.Exit(1)
	}
	if doc.Type != html.DocumentNode {
		fmt.Fprintf(os.Stderr, "assertion 2 failed: expected DocumentNode at root, got %v\n", doc.Type)
		os.Exit(1)
	}

	counts := make(map[html.NodeType]int)
	var walk func(*html.Node)
	walk = func(n *html.Node) {
		if n == nil {
			return
		}
		counts[n.Type]++
		for c := n.FirstChild; c != nil; c = c.NextSibling {
			walk(c)
		}
	}
	walk(doc)

	if counts[html.DocumentNode] != 1 {
		fmt.Fprintf(os.Stderr, "assertion 2 failed: expected 1 DocumentNode, got %d\n", counts[html.DocumentNode])
		os.Exit(1)
	}
	if counts[html.DoctypeNode] != 1 {
		fmt.Fprintf(os.Stderr, "assertion 2 failed: expected 1 DoctypeNode, got %d\n", counts[html.DoctypeNode])
		os.Exit(1)
	}
	if counts[html.CommentNode] != 1 {
		fmt.Fprintf(os.Stderr, "assertion 2 failed: expected 1 CommentNode, got %d\n", counts[html.CommentNode])
		os.Exit(1)
	}
	if counts[html.ElementNode] < 4 {
		fmt.Fprintf(os.Stderr, "assertion 2 failed: expected at least 4 ElementNodes, got %d\n", counts[html.ElementNode])
		os.Exit(1)
	}
	if counts[html.TextNode] != 1 {
		fmt.Fprintf(os.Stderr, "assertion 2 failed: expected 1 TextNode, got %d\n", counts[html.TextNode])
		os.Exit(1)
	}

	// Assertion 3: Manually constructed html.Node instances preserve their html.NodeType across tree attachment
	container := &html.Node{Type: html.ElementNode, Data: "div"}
	comment := &html.Node{Type: html.CommentNode, Data: "meta"}
	text := &html.Node{Type: html.TextNode, Data: "hello"}
	container.AppendChild(comment)
	container.AppendChild(text)

	if container.Type != html.ElementNode ||
		container.FirstChild.Type != html.CommentNode ||
		container.LastChild.Type != html.TextNode {
		fmt.Fprintf(os.Stderr, "assertion 3 failed: unexpected node types after AppendChild\n")
		os.Exit(1)
	}

	fmt.Println("Contract passed.")
}