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

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.Run 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.Run

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:sha256:06d273c2122bc4df9162eeb7ce428f69cb217202281445b817c77e32de977c04","contract":["blackfriday.Run converts markdown input bytes into formatted HTML output for headings, paragraphs, and inline formatting","blackfriday.Run with WithExtensions processes enabled markdown extensions such as FencedCode, Tables, and Strikethrough","blackfriday.Run with WithNoExtensions processes markdown input with all extension processing disabled","blackfriday.Run with WithRenderer renders parsed markdown using a custom configured HTMLRenderer","blackfriday.Run returns an empty byte slice when given empty markdown input","blackfriday.Run with WithRefOverride resolves custom markdown link reference overrides"],"goal":"verify github.com/russross/blackfriday/v2.Run 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.Run"]},"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.Run"],"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("# Hello Blackfriday\n\nRender **Markdown** into *HTML* with `blackfriday.Run`.")
	html := blackfriday.Run(markdown)
	fmt.Printf("Rendered HTML:\n%s\n", string(html))
}

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

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 blackfriday.Run contract assertions passed successfully.")
}

func runContract() error {
	// Assertion 1: blackfriday.Run converts markdown input bytes into formatted HTML output for headings, paragraphs, and inline formatting
	input := []byte("# Hello World\n\nThis is **bold** and *italic* text.")
	output := blackfriday.Run(input)
	expectedSubstrings := []string{
		"<h1>Hello World</h1>",
		"<p>This is <strong>bold</strong> and <em>italic</em> text.</p>",
	}
	for _, expected := range expectedSubstrings {
		if !strings.Contains(string(output), expected) {
			return fmt.Errorf("expected %q in Run output, got: %s", expected, string(output))
		}
	}

	// Assertion 2: blackfriday.Run with WithExtensions processes enabled markdown extensions such as FencedCode, Tables, and Strikethrough
	extInput := []byte("~~deleted~~\n\n```go\nfmt.Println(1)\n```\n\n| Header |\n| --- |\n| Cell |\n")
	extOutput := blackfriday.Run(
		extInput,
		blackfriday.WithExtensions(blackfriday.Strikethrough|blackfriday.FencedCode|blackfriday.Tables),
	)
	if !strings.Contains(string(extOutput), "<del>deleted</del>") {
		return fmt.Errorf("expected <del> tag for strikethrough, got: %s", string(extOutput))
	}
	if !strings.Contains(string(extOutput), "<pre><code class=\"language-go\">fmt.Println(1)\n</code></pre>") {
		return fmt.Errorf("expected fenced code block, got: %s", string(extOutput))
	}
	if !strings.Contains(string(extOutput), "<table>") || !strings.Contains(string(extOutput), "<td>Cell</td>") {
		return fmt.Errorf("expected table elements, got: %s", string(extOutput))
	}

	// Assertion 3: blackfriday.Run with WithNoExtensions processes markdown input with all extension processing disabled
	noExtInput := []byte("```go\nfmt.Println(1)\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 WithNoExtensions is used, got: %s", string(noExtOutput))
	}

	// Assertion 4: blackfriday.Run with WithRenderer renders parsed markdown using a custom configured HTMLRenderer
	params := blackfriday.HTMLRendererParameters{
		HeadingLevelOffset: 1,
		HeadingIDPrefix:    "section-",
		Flags:              blackfriday.CommonHTMLFlags,
	}
	renderer := blackfriday.NewHTMLRenderer(params)
	customOutput := blackfriday.Run(
		[]byte("# Title"),
		blackfriday.WithRenderer(renderer),
		blackfriday.WithExtensions(blackfriday.AutoHeadingIDs),
	)
	expectedCustom := `<h2 id="section-title">Title</h2>`
	if !strings.Contains(string(customOutput), expectedCustom) {
		return fmt.Errorf("expected %q with custom renderer, got: %s", expectedCustom, string(customOutput))
	}

	// Assertion 5: blackfriday.Run returns an empty byte slice when given empty or whitespace-only markdown input
	emptyOutput := blackfriday.Run([]byte(""))
	if len(emptyOutput) != 0 {
		return fmt.Errorf("expected empty byte slice for empty input, got length %d: %q", len(emptyOutput), string(emptyOutput))
	}

	// Assertion 6: blackfriday.Run with WithRefOverride resolves custom markdown link reference overrides
	refInput := []byte("Check the [documentation][docs] link.")
	refOutput := blackfriday.Run(
		refInput,
		blackfriday.WithRefOverride(func(reference string) (*blackfriday.Reference, bool) {
			if reference == "docs" {
				return &blackfriday.Reference{
					Link:  "https://example.com/docs",
					Title: "Documentation",
				}, true
			}
			return nil, false
		}),
	)
	expectedLink := `<p>Check the <a href="https://example.com/docs" title="Documentation">documentation</a> link.</p>`
	if !bytes.Equal(bytes.TrimSpace(refOutput), []byte(expectedLink)) {
		return fmt.Errorf("expected %q for ref override, got: %q", expectedLink, string(refOutput))
	}

	return nil
}