github.com/sergi/go-diff v1.2.0

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/sergi/go-diff@v1.2.0
Kind: HOW

Use EXACTLY these public packages and versions:
  - pkg:golang/github.com/sergi/go-diff@v1.2.0

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:sha256:7a0b2616d6d1482d4f5d3071ac28abfc2daebc4e993c60f4398e1810911a16dd","contract":["diffmatchpatch.New().DiffMain computes diffs whose DiffText1 and DiffText2 reconstruct the original and modified texts","diffmatchpatch.New().PatchMake, PatchToText, PatchFromText, and PatchApply round-trip patches to transform the source text into the target text"],"goal":"verify pkg:golang/github.com/sergi/go-diff@v1.2.0","kind":"HOW","packages":["pkg:golang/github.com/sergi/go-diff@v1.2.0"],"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/sergi/go-diff@v1.2.0"],"schemaVersion":1,"subject":"pkg:golang/github.com/sergi/go-diff@v1.2.0","verifierAdapter":"golang@1"}

module sample

go 1.21

require github.com/sergi/go-diff v1.2.0

github.com/davecgh/go-spew v1.1.0/go.mod h1:J7Y8YcW2NihsgmVo/mv3lAwl/skON4iLHjSsI+c5H38=
github.com/davecgh/go-spew v1.1.1 h1:vj9j/u1bqnvCEfJOwUhtlOARqs3+rkHYY13jYWTU97c=
github.com/davecgh/go-spew v1.1.1/go.mod h1:J7Y8YcW2NihsgmVo/mv3lAwl/skON4iLHjSsI+c5H38=
github.com/kr/pretty v0.1.0/go.mod h1:dAy3ld7l9f0ibDNOQOHHMYYIIbhfbHSm3C4ZsoJORNo=
github.com/kr/pty v1.1.1/go.mod h1:pFQYn66WHrOpPYNljwOMqo10TkYh1fy3cYio2l3bCsQ=
github.com/kr/text v0.1.0/go.mod h1:4Jbv+DJW3UT/LiOwJeYQe1efqtUx/iVham/4vfdArNI=
github.com/pmezard/go-difflib v1.0.0 h1:4DBwDE0NGyQoBHbLQYPwSUPoCMWR5BEzIk/f1lZbAQM=
github.com/pmezard/go-difflib v1.0.0/go.mod h1:iKH77koFhYxTK1pcRnkKkqfTogsbg7gZNVY4sRDYZ/4=
github.com/sergi/go-diff v1.2.0 h1:XU+rvMAioB0UC3q1MFrIQy4Vo5/4VsRDQQXHsEya6xQ=
github.com/sergi/go-diff v1.2.0/go.mod h1:STckp+ISIX8hZLjrqAeVduY0gWCT9IjLuqbuNXdaHfM=
github.com/stretchr/objx v0.1.0/go.mod h1:HFkY916IF+rwdDfMAkV7OtwuqBVzrE8GR6GFx+wExME=
github.com/stretchr/testify v1.4.0 h1:2E4SXV/wtOkTonXsotYi4li6zVWxYlZuYNCXe9XRJyk=
github.com/stretchr/testify v1.4.0/go.mod h1:j7eGeouHqKxXV5pUuKE4zz7dFj8WfuZ+81PSLYec5m4=
gopkg.in/check.v1 v0.0.0-20161208181325-20d25e280405/go.mod h1:Co6ibVJAznAaIkqp8huTwlJQCZ016jof/cbN4VW5Yz0=
gopkg.in/check.v1 v1.0.0-20190902080502-41f04d3bba15/go.mod h1:Co6ibVJAznAaIkqp8huTwlJQCZ016jof/cbN4VW5Yz0=
gopkg.in/yaml.v2 v2.2.2/go.mod h1:hI93XBmqTisBFMUTm0b8Fm+jr3Dg1NNxqwp+5A1VGuI=
gopkg.in/yaml.v2 v2.2.4 h1:/eiJrUcujPVeJ3xlSWaiNi3uSVmDGBK1pDHUHAnao1I=
gopkg.in/yaml.v2 v2.2.4/go.mod h1:hI93XBmqTisBFMUTm0b8Fm+jr3Dg1NNxqwp+5A1VGuI=

{
  "schemaVersion": 1,
  "goal": "verify pkg:golang/github.com/sergi/go-diff@v1.2.0",
  "kind": "HOW",
  "packages": [
    "pkg:golang/github.com/sergi/go-diff@v1.2.0"
  ]
}

package main

import (
	"fmt"
	"os"
	"strings"

	"github.com/sergi/go-diff/diffmatchpatch"
)

func main() {
	dmp := diffmatchpatch.New()

	text1 := "alpha\nbeta\ngamma\n"
	text2 := "alpha\nbeta2\ngamma\ndelta\n"

	diffs := dmp.DiffMain(text1, text2, false)
	if len(diffs) == 0 {
		fmt.Fprintln(os.Stderr, "expected non-empty diffs")
		os.Exit(1)
	}

	reconstructed1 := dmp.DiffText1(diffs)
	if reconstructed1 != text1 {
		fmt.Fprintf(os.Stderr, "DiffText1 mismatch: got %q, want %q\n", reconstructed1, text1)
		os.Exit(1)
	}

	reconstructed2 := dmp.DiffText2(diffs)
	if reconstructed2 != text2 {
		fmt.Fprintf(os.Stderr, "DiffText2 mismatch: got %q, want %q\n", reconstructed2, text2)
		os.Exit(1)
	}

	lev := dmp.DiffLevenshtein(diffs)
	if lev <= 0 {
		fmt.Fprintf(os.Stderr, "expected positive Levenshtein distance, got %d\n", lev)
		os.Exit(1)
	}

	pretty := dmp.DiffPrettyText(diffs)
	if !strings.Contains(pretty, "alpha") || !strings.Contains(pretty, "delta") {
		fmt.Fprintf(os.Stderr, "unexpected DiffPrettyText output: %q\n", pretty)
		os.Exit(1)
	}

	patches := dmp.PatchMake(text1, diffs)
	if len(patches) == 0 {
		fmt.Fprintln(os.Stderr, "expected non-empty patches")
		os.Exit(1)
	}

	patchText := dmp.PatchToText(patches)
	parsedPatches, err := dmp.PatchFromText(patchText)
	if err != nil {
		fmt.Fprintf(os.Stderr, "PatchFromText error: %v\n", err)
		os.Exit(1)
	}

	patched, applied := dmp.PatchApply(parsedPatches, text1)
	if patched != text2 {
		fmt.Fprintf(os.Stderr, "PatchApply text mismatch: got %q, want %q\n", patched, text2)
		os.Exit(1)
	}
	for i, ok := range applied {
		if !ok {
			fmt.Fprintf(os.Stderr, "patch %d failed to apply\n", i)
			os.Exit(1)
		}
	}
}