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

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.FencedCode 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.FencedCode

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:sha256:13441d9cfdbdf7a7eb449b78447700f310e41f1739773203b0d85221f436ea04","contract":["blackfriday.FencedCode enables parsing backtick fenced code blocks into pre code HTML elements with language class","blackfriday.FencedCode enables parsing tilde fenced code blocks into pre code HTML elements with language class","blackfriday.New with FencedCode parses fenced code blocks into AST CodeBlock nodes with Info and Literal data","blackfriday.WithNoExtensions renders unextended backticks as inline code paragraph rather than fenced pre code block"],"goal":"verify github.com/russross/blackfriday/v2.FencedCode 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.FencedCode"]},"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.FencedCode"],"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("```go\npackage main\n\nfunc main() {\n\tprintln(\"Hello, world!\")\n}\n```")
	html := blackfriday.Run(markdown, blackfriday.WithExtensions(blackfriday.FencedCode))
	fmt.Printf("Rendered HTML:\n%s\n", string(html))
}

{
  "schemaVersion": 1,
  "goal": "verify github.com/russross/blackfriday/v2.FencedCode 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.FencedCode"
  ]
}

package main

import (
	"bytes"
	"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 FencedCode contract assertions passed successfully.")
}

func runContract() error {
	// Assertion 1: blackfriday.FencedCode enables parsing backtick fenced code blocks into pre code HTML elements with language class
	backtickInput := []byte("```go\nfmt.Println(\"testing\")\n```")
	backtickOutput := blackfriday.Run(backtickInput, blackfriday.WithExtensions(blackfriday.FencedCode))
	expectedBacktick := "<pre><code class=\"language-go\">fmt.Println(&quot;testing&quot;)\n</code></pre>"
	if !strings.Contains(string(backtickOutput), expectedBacktick) {
		return fmt.Errorf("expected %q in FencedCode backtick output, got: %s", expectedBacktick, string(backtickOutput))
	}

	// Assertion 2: blackfriday.FencedCode enables parsing tilde fenced code blocks into pre code HTML elements with language class
	tildeInput := []byte("~~~python\nprint('fenced with tildes')\n~~~")
	tildeOutput := blackfriday.Run(tildeInput, blackfriday.WithExtensions(blackfriday.FencedCode))
	expectedTilde := "<pre><code class=\"language-python\">print('fenced with tildes')\n</code></pre>"
	if !strings.Contains(string(tildeOutput), expectedTilde) {
		return fmt.Errorf("expected %q in FencedCode tilde output, got: %s", expectedTilde, string(tildeOutput))
	}

	// Assertion 3: blackfriday.New with FencedCode parses fenced code blocks into AST CodeBlock nodes with Info and Literal data
	parser := blackfriday.New(blackfriday.WithExtensions(blackfriday.FencedCode))
	ast := parser.Parse([]byte("```json\n{\"status\": \"ok\"}\n```"))
	if ast == nil || ast.Type != blackfriday.Document {
		return fmt.Errorf("expected Document AST root node, got: %v", ast)
	}
	codeBlockNode := ast.FirstChild
	if codeBlockNode == nil || codeBlockNode.Type != blackfriday.CodeBlock {
		return fmt.Errorf("expected CodeBlock AST node, got: %v", codeBlockNode)
	}
	if string(codeBlockNode.CodeBlockData.Info) != "json" {
		return fmt.Errorf("expected CodeBlock info 'json', got %q", string(codeBlockNode.CodeBlockData.Info))
	}
	expectedLiteral := []byte("{\"status\": \"ok\"}\n")
	if !bytes.Equal(codeBlockNode.Literal, expectedLiteral) {
		return fmt.Errorf("expected CodeBlock literal %q, got %q", string(expectedLiteral), string(codeBlockNode.Literal))
	}

	// Assertion 4: blackfriday.WithNoExtensions renders unextended backticks as inline code paragraph rather than fenced pre code block
	noExtOutput := blackfriday.Run(backtickInput, blackfriday.WithNoExtensions())
	if strings.Contains(string(noExtOutput), "<pre><code") {
		return fmt.Errorf("expected no pre/code elements with WithNoExtensions, got: %s", string(noExtOutput))
	}
	expectedInline := "<p><code>go\nfmt.Println(&quot;testing&quot;)\n</code></p>"
	if !strings.Contains(string(noExtOutput), expectedInline) {
		return fmt.Errorf("expected inline code paragraph with WithNoExtensions, got: %s", string(noExtOutput))
	}

	return nil
}