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

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 github.com/russross/blackfriday/v2.CommonExtensions in 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
Demonstrate these symbols/APIs:
  - github.com/russross/blackfriday/v2.CommonExtensions
Constraints:
  - executionContext: node
Required runtime conditions:
  - ecosystem: npm
  - language: javascript
  - moduleSystem: cjs
  - packageManager: npm@10.9.8
  - runtime: node@22.23.2

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:sha256:698e69f67940a4008647470a1420d5cd79ab149f5a19cb96e355012be343e940","contract":["blackfriday.CommonExtensions enables GFM table rendering into table, thead, and tbody elements","blackfriday.CommonExtensions enables fenced code blocks with language CSS classes","blackfriday.CommonExtensions enables strikethrough syntax converted to del tags","blackfriday.CommonExtensions enables autolink conversion of raw URLs into anchor hyperlinks"],"goal":"verify github.com/russross/blackfriday/v2.CommonExtensions in 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,"symbols":["github.com/russross/blackfriday/v2.CommonExtensions"]},"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","symbols":["github.com/russross/blackfriday/v2.CommonExtensions"],"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() {
	markdown := []byte("# Markdown Overview\n\n| Feature | Supported |\n| --- | --- |\n| Tables | Yes |\n| Fenced Code | Yes |\n\n```go\nfunc example() {}\n```\n\nVisit https://example.com or ~~draft~~ final text.")
	html := blackfriday.Run(markdown, blackfriday.WithExtensions(blackfriday.CommonExtensions))
	fmt.Printf("Rendered HTML:\n%s\n", string(html))
}

{
  "schemaVersion": 1,
  "goal": "verify github.com/russross/blackfriday/v2.CommonExtensions in pkg:golang/github.com/russross/blackfriday/v2@v2.1.0",
  "kind": "HOW",
  "packages": [
    "pkg:golang/github.com/russross/blackfriday/v2@v2.1.0"
  ],
  "symbols": [
    "github.com/russross/blackfriday/v2.CommonExtensions"
  ],
  "constraints": {
    "executionContext": "node"
  },
  "runtimeConditions": {
    "ecosystem": "npm",
    "language": "javascript",
    "moduleSystem": "cjs",
    "packageManager": "npm@10.9.8",
    "runtime": "node@22.23.2"
  }
}

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 CommonExtensions contract assertions passed successfully.")
}

func runContract() error {
	// Assertion 1: CommonExtensions enables GFM table rendering into table, thead, and tbody elements
	inputTable := []byte("| Col A | Col B |\n| --- | --- |\n| Val 1 | Val 2 |")
	outputTable := blackfriday.Run(inputTable, blackfriday.WithExtensions(blackfriday.CommonExtensions))
	outTableStr := string(outputTable)
	if !strings.Contains(outTableStr, "<table>") || !strings.Contains(outTableStr, "<th>Col A</th>") || !strings.Contains(outTableStr, "<td>Val 1</td>") {
		return fmt.Errorf("expected HTML table structure in CommonExtensions output, got: %s", outTableStr)
	}

	// Assertion 2: CommonExtensions enables fenced code blocks with language CSS classes
	inputFenced := []byte("```go\nfunc hello() string { return \"world\" }\n```")
	outputFenced := blackfriday.Run(inputFenced, blackfriday.WithExtensions(blackfriday.CommonExtensions))
	outFencedStr := string(outputFenced)
	if !strings.Contains(outFencedStr, `<pre><code class="language-go">`) {
		return fmt.Errorf("expected fenced code block with class 'language-go', got: %s", outFencedStr)
	}

	// Assertion 3: CommonExtensions enables strikethrough syntax converted to del tags
	inputStrike := []byte("This is ~~deprecated~~ modern syntax.")
	outputStrike := blackfriday.Run(inputStrike, blackfriday.WithExtensions(blackfriday.CommonExtensions))
	outStrikeStr := string(outputStrike)
	if !strings.Contains(outStrikeStr, "<del>deprecated</del>") {
		return fmt.Errorf("expected <del> tag for strikethrough, got: %s", outStrikeStr)
	}

	// Assertion 4: CommonExtensions enables autolink conversion of raw URLs into anchor hyperlinks
	inputAutolink := []byte("Check docs at https://example.com/guide for details.")
	outputAutolink := blackfriday.Run(inputAutolink, blackfriday.WithExtensions(blackfriday.CommonExtensions))
	outAutolinkStr := string(outputAutolink)
	if !strings.Contains(outAutolinkStr, `<a href="https://example.com/guide">https://example.com/guide</a>`) {
		return fmt.Errorf("expected autolink anchor tag, got: %s", outAutolinkStr)
	}

	return nil
}