github.com/google/go-cmp v0.5.1: cmpopts.SortSlices

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/google/go-cmp/cmp/cmpopts.SortSlices in pkg:golang/github.com/google/go-cmp@v0.5.1
Kind: HOW

Use EXACTLY these public packages and versions:
  - pkg:golang/github.com/google/go-cmp@v0.5.1
Demonstrate these symbols/APIs:
  - github.com/google/go-cmp/cmp/cmpopts.SortSlices

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:cbed0e81ab562750129d85b6ea0170ca565e81b0db44d49f901c405049d4f636","contract":["cmpopts.SortSlices sorts slices of comparable elements using a less function before comparison with cmp.Equal and cmp.Diff","cmpopts.SortSlices does not mutate the original input slices during comparison","cmpopts.SortSlices sorts struct slices with a custom less function so elements in different orders compare equal","cmpopts.SortSlices detects differences when slice elements or counts do not match","cmpopts.SortSlices panics when given a function without the func(T, T) bool signature"],"goal":"verify github.com/google/go-cmp/cmp/cmpopts.SortSlices in pkg:golang/github.com/google/go-cmp@v0.5.1","kind":"HOW","packages":["pkg:golang/github.com/google/go-cmp@v0.5.1"],"schemaVersion":1,"symbols":["github.com/google/go-cmp/cmp/cmpopts.SortSlices"]},"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/google/go-cmp@v0.5.1"],"schemaVersion":1,"subject":"pkg:golang/github.com/google/go-cmp@v0.5.1","symbols":["github.com/google/go-cmp/cmp/cmpopts.SortSlices"],"verifierAdapter":"golang@1"}

module example.com/sample

go 1.21

require github.com/google/go-cmp v0.5.1

require golang.org/x/xerrors v0.0.0-20191204190536-9bdfabe68543 // indirect

github.com/google/go-cmp v0.5.1 h1:JFrFEBb2xKufg6XkJsJr+WbKb4FQlURi5RUcBveYu9k=
github.com/google/go-cmp v0.5.1/go.mod h1:v8dTdLbMG2kIc/vJvl+f65V22dbkXbowE6jgT/gNBxE=
golang.org/x/xerrors v0.0.0-20191204190536-9bdfabe68543 h1:E7g+9GITq07hpfrRu66IVDexMakfv52eLZ2CXBWiKr4=
golang.org/x/xerrors v0.0.0-20191204190536-9bdfabe68543/go.mod h1:I/5z698sn9Ka8TeJc9MKroUUfqBBauWjQqLJ2OPfmY0=

{
  "schemaVersion": 1,
  "goal": "verify github.com/google/go-cmp/cmp/cmpopts.SortSlices in pkg:golang/github.com/google/go-cmp@v0.5.1",
  "kind": "HOW",
  "packages": [
    "pkg:golang/github.com/google/go-cmp@v0.5.1"
  ],
  "symbols": [
    "github.com/google/go-cmp/cmp/cmpopts.SortSlices"
  ]
}

package main

import (
	"fmt"
	"os"
	"reflect"

	"github.com/google/go-cmp/cmp"
	"github.com/google/go-cmp/cmp/cmpopts"
)

type item struct {
	ID   int
	Name string
}

func assertPanics(name string, fn func()) {
	defer func() {
		if r := recover(); r == nil {
			fmt.Fprintf(os.Stderr, "FAIL: expected panic for %s\n", name)
			os.Exit(1)
		}
	}()
	fn()
}

func main() {
	// 1. SortSlices sorts integer slices using a less function before comparison with cmp.Equal and cmp.Diff.
	intLess := func(a, b int) bool { return a < b }
	intOpt := cmpopts.SortSlices(intLess)

	sliceA := []int{3, 1, 4, 1, 5}
	sliceB := []int{1, 1, 3, 4, 5}
	if !cmp.Equal(sliceA, sliceB, intOpt) {
		fmt.Fprintln(os.Stderr, "FAIL: expected slices with same elements in different order to be equal")
		os.Exit(1)
	}
	if diff := cmp.Diff(sliceA, sliceB, intOpt); diff != "" {
		fmt.Fprintf(os.Stderr, "FAIL: expected empty diff for equal multiset slices, got: %s\n", diff)
		os.Exit(1)
	}

	// 2. SortSlices does not mutate the original input slices during comparison.
	expectedOriginalA := []int{3, 1, 4, 1, 5}
	if !reflect.DeepEqual(sliceA, expectedOriginalA) {
		fmt.Fprintf(os.Stderr, "FAIL: input slice was mutated: got %v\n", sliceA)
		os.Exit(1)
	}

	// 3. SortSlices sorts slices of structs by custom less function before comparison.
	itemLess := func(a, b item) bool {
		if a.ID != b.ID {
			return a.ID < b.ID
		}
		return a.Name < b.Name
	}
	itemOpt := cmpopts.SortSlices(itemLess)
	itemsA := []item{{ID: 2, Name: "beta"}, {ID: 1, Name: "alpha"}}
	itemsB := []item{{ID: 1, Name: "alpha"}, {ID: 2, Name: "beta"}}
	if !cmp.Equal(itemsA, itemsB, itemOpt) {
		fmt.Fprintln(os.Stderr, "FAIL: expected struct slices with same elements in different order to be equal")
		os.Exit(1)
	}

	// 4. SortSlices detects differences when slice elements or frequencies do not match.
	sliceC := []int{1, 3, 3, 4, 5}
	if cmp.Equal(sliceA, sliceC, intOpt) {
		fmt.Fprintln(os.Stderr, "FAIL: expected slices with different element counts to be unequal")
		os.Exit(1)
	}
	if diff := cmp.Diff(sliceA, sliceC, intOpt); diff == "" {
		fmt.Fprintln(os.Stderr, "FAIL: expected non-empty diff for unequal slices")
		os.Exit(1)
	}

	// 5. SortSlices panics when given an invalid less function signature.
	assertPanics("invalid signature (one arg)", func() {
		cmpopts.SortSlices(func(a int) bool { return a > 0 })
	})
	assertPanics("invalid signature (non-bool return)", func() {
		cmpopts.SortSlices(func(a, b int) int { return a - b })
	})
}