github.com/russross/blackfriday/v2 v2.1.0

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/github.com/russross/blackfriday/v2@v2.1.0
Kind: HOW

Use EXACTLY these public packages and versions:
  - pkg:golang/github.com/russross/blackfriday/v2@v2.1.0

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:a86fe6b35d1e7ca606b8c37fb2b3fad71404150cf1adbd91d9871f885e711925","contract":["blackfriday.Run converts Markdown input into HTML formatted output for standard headings, paragraphs, bold, and italic text","blackfriday.WithExtensions enables extended markdown features including Strikethrough, Tables, and FencedCode","blackfriday.WithNoExtensions disables default markdown extension processing","blackfriday.NewHTMLRenderer configures custom HTML rendering parameters including HeadingLevelOffset and HeadingIDPrefix with AutoHeadingIDs","blackfriday.SanitizedAnchorName generates lowercase URL-safe slug identifiers from heading text","blackfriday.New constructs a Markdown parser instance and Parse produces an AST document tree with Heading and Document nodes"],"goal":"verify pkg:golang/github.com/russross/blackfriday/v2@v2.1.0","kind":"HOW","packages":["pkg:golang/github.com/russross/blackfriday/v2@v2.1.0"],"schemaVersion":1},"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/github.com/russross/blackfriday/v2@v2.1.0"],"schemaVersion":1,"subject":"pkg:golang/github.com/russross/blackfriday/v2@v2.1.0","verifierAdapter":"golang@1"}

module sample

go 1.26.6

require github.com/russross/blackfriday/v2 v2.1.0

github.com/russross/blackfriday/v2 v2.1.0 h1:JIOH55/0cWyOuilr9/qlrm0BSXldqnqwMsf35Ld67mk=
github.com/russross/blackfriday/v2 v2.1.0/go.mod h1:+Rmxgy9KzJVeS9/2gXHxylqXiyQDYRxCVz55jmeOWTM=

package main

import (
	"fmt"

	"github.com/russross/blackfriday/v2"
)

func main() {
	markdownInput := []byte("# Blackfriday Sample\n\nRender markdown to **HTML** safely.")
	htmlOutput := blackfriday.Run(markdownInput)
	fmt.Printf("Rendered HTML:\n%s\n", string(htmlOutput))

	slug := blackfriday.SanitizedAnchorName("Blackfriday Sample Anchor")
	fmt.Printf("Sanitized Anchor Slug: %s\n", slug)
}

{
  "schemaVersion": 1,
  "goal": "verify pkg:golang/github.com/russross/blackfriday/v2@v2.1.0",
  "kind": "HOW",
  "packages": [
    "pkg:golang/github.com/russross/blackfriday/v2@v2.1.0"
  ]
}

package main

import (
	"fmt"
	"os"
	"strings"

	"github.com/russross/blackfriday/v2"
)

func main() {
	if err := runContract(); err != nil {
		fmt.Fprintf(os.Stderr, "Contract verification failed: %v\n", err)
		os.Exit(1)
	}
	fmt.Println("All contract assertions passed successfully.")
}

func runContract() error {
	// Assertion 1: blackfriday.Run converts Markdown input into HTML formatted output for standard headings, paragraphs, bold, and italic text
	input := []byte("# Main Heading\n\nThis is **bold** text and *italic* text.")
	output := blackfriday.Run(input)
	outputStr := string(output)
	if !strings.Contains(outputStr, "<h1>Main Heading</h1>") {
		return fmt.Errorf("expected <h1> tag, got: %s", outputStr)
	}
	if !strings.Contains(outputStr, "<p>This is <strong>bold</strong> text and <em>italic</em> text.</p>") {
		return fmt.Errorf("expected paragraph with strong and em tags, got: %s", outputStr)
	}

	// Assertion 2: blackfriday.WithExtensions enables extended markdown features including Strikethrough, Tables, and FencedCode
	extMarkdown := []byte("~~deleted text~~\n\n```go\nfmt.Println(\"test\")\n```\n\n| Item | Qty |\n| --- | --- |\n| Apple | 5 |\n")
	extOutput := blackfriday.Run(
		extMarkdown,
		blackfriday.WithExtensions(blackfriday.Strikethrough|blackfriday.FencedCode|blackfriday.Tables),
	)
	extOutputStr := string(extOutput)
	if !strings.Contains(extOutputStr, "<del>deleted text</del>") {
		return fmt.Errorf("expected <del> tag in strikethrough output, got: %s", extOutputStr)
	}
	if !strings.Contains(extOutputStr, "<pre><code class=\"language-go\">") {
		return fmt.Errorf("expected fenced code block output, got: %s", extOutputStr)
	}
	if !strings.Contains(extOutputStr, "<table>") || !strings.Contains(extOutputStr, "<td>Apple</td>") {
		return fmt.Errorf("expected table rendering, got: %s", extOutputStr)
	}

	// Assertion 3: blackfriday.WithNoExtensions disables default markdown extension processing
	noExtInput := []byte("```go\ncode\n```")
	noExtOutput := blackfriday.Run(noExtInput, blackfriday.WithNoExtensions())
	if strings.Contains(string(noExtOutput), "<code class=\"language-go\">") {
		return fmt.Errorf("expected no fenced code block when extensions disabled, got: %s", string(noExtOutput))
	}

	// Assertion 4: blackfriday.NewHTMLRenderer configures custom HTML rendering parameters including HeadingLevelOffset and HeadingIDPrefix with AutoHeadingIDs
	params := blackfriday.HTMLRendererParameters{
		HeadingLevelOffset: 1,
		HeadingIDPrefix:    "section-",
		Flags:              blackfriday.CommonHTMLFlags,
	}
	renderer := blackfriday.NewHTMLRenderer(params)
	customOutput := blackfriday.Run(
		[]byte("# Section Title"),
		blackfriday.WithRenderer(renderer),
		blackfriday.WithExtensions(blackfriday.AutoHeadingIDs),
	)
	customOutputStr := string(customOutput)
	if !strings.Contains(customOutputStr, `<h2 id="section-section-title">Section Title</h2>`) {
		return fmt.Errorf("expected offset heading h2 with id prefix 'section-section-title', got: %s", customOutputStr)
	}

	// Assertion 5: blackfriday.SanitizedAnchorName generates lowercase URL-safe slug identifiers from heading text
	slug1 := blackfriday.SanitizedAnchorName("Getting Started with Blackfriday!")
	if slug1 != "getting-started-with-blackfriday" {
		return fmt.Errorf("SanitizedAnchorName failed: expected 'getting-started-with-blackfriday', got %q", slug1)
	}

	slug2 := blackfriday.SanitizedAnchorName("  Special & Header #42 (Alpha)  ")
	if slug2 != "special-header-42-alpha" {
		return fmt.Errorf("SanitizedAnchorName failed: expected 'special-header-42-alpha', got %q", slug2)
	}

	// Assertion 6: blackfriday.New constructs a Markdown parser instance and Parse produces an AST document tree with Heading and Document nodes
	parser := blackfriday.New(blackfriday.WithExtensions(blackfriday.CommonExtensions | blackfriday.AutoHeadingIDs))
	ast := parser.Parse([]byte("# Document Root Heading\n\nBody paragraph text."))
	if ast == nil || ast.Type != blackfriday.Document {
		return fmt.Errorf("expected Document AST root node, got: %v", ast)
	}
	firstChild := ast.FirstChild
	if firstChild == nil || firstChild.Type != blackfriday.Heading {
		return fmt.Errorf("expected Heading AST first child node, got: %v", firstChild)
	}
	if firstChild.HeadingData.HeadingID != "document-root-heading" {
		return fmt.Errorf("expected HeadingID 'document-root-heading', got %q", firstChild.HeadingData.HeadingID)
	}

	return nil
}