github.com/google/go-cmp v0.5.4: cmpopts.EquateEmpty

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.EquateEmpty in pkg:golang/github.com/google/go-cmp@v0.5.4
Kind: HOW

Use EXACTLY these public packages and versions:
  - pkg:golang/github.com/google/go-cmp@v0.5.4
Demonstrate these symbols/APIs:
  - github.com/google/go-cmp/cmp/cmpopts.EquateEmpty

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:aa20bbcaeff4411f684aa19c15e9441290c0cf584169d5cddc0b477083ac993f","contract":["cmpopts.EquateEmpty treats nil and empty slices of the same type as equal","cmpopts.EquateEmpty treats nil and empty maps of the same type as equal","cmpopts.EquateEmpty preserves inequality for non-empty slices or maps with different elements","cmpopts.EquateEmpty equates empty slices and maps nested within structs"],"goal":"verify github.com/google/go-cmp/cmp/cmpopts.EquateEmpty in pkg:golang/github.com/google/go-cmp@v0.5.4","kind":"HOW","packages":["pkg:golang/github.com/google/go-cmp@v0.5.4"],"schemaVersion":1,"symbols":["github.com/google/go-cmp/cmp/cmpopts.EquateEmpty"]},"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@v0.5.4"],"schemaVersion":1,"subject":"pkg:golang/github.com/google/go-cmp@v0.5.4","symbols":["github.com/google/go-cmp/cmp/cmpopts.EquateEmpty"],"verifierAdapter":"golang@1"}

module sample

go 1.22.0

require github.com/google/go-cmp v0.5.4

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

github.com/google/go-cmp v0.5.4 h1:L8R9j+yAqZuZjsqh/z+F1NCffTKKLShY6zXTItVIZ8M=
github.com/google/go-cmp v0.5.4/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=

package main

import (
	"fmt"

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

// DataContainer represents a structure with slice and map fields.
type DataContainer struct {
	Name   string
	Tags   []string
	Values map[string]int
}

// CompareContainers compares two DataContainer structs treating empty slices/maps as equal to nil.
func CompareContainers(a, b DataContainer) bool {
	return cmp.Equal(a, b, cmpopts.EquateEmpty())
}

func main() {
	c1 := DataContainer{
		Name:   "item-1",
		Tags:   []string{},
		Values: map[string]int{},
	}
	c2 := DataContainer{
		Name:   "item-1",
		Tags:   nil,
		Values: nil,
	}

	defaultEqual := cmp.Equal(c1, c2)
	equateEmptyEqual := CompareContainers(c1, c2)

	fmt.Printf("Default cmp.Equal: %v\n", defaultEqual)
	fmt.Printf("With cmpopts.EquateEmpty: %v\n", equateEmptyEqual)
}

{
  "schemaVersion": 1,
  "goal": "verify github.com/google/go-cmp/cmp/cmpopts.EquateEmpty in pkg:golang/github.com/google/go-cmp@v0.5.4",
  "kind": "HOW",
  "packages": [
    "pkg:golang/github.com/google/go-cmp@v0.5.4"
  ],
  "symbols": [
    "github.com/google/go-cmp/cmp/cmpopts.EquateEmpty"
  ]
}

package main

import (
	"fmt"
	"os"

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

type structWithCollections struct {
	ID     int
	Labels []string
	Attrs  map[string]string
}

func main() {
	// Assertion 1: cmpopts.EquateEmpty treats nil and empty slices of the same type as equal
	{
		var nilSlice []string
		emptySlice := []string{}

		if cmp.Equal(nilSlice, emptySlice) {
			fmt.Fprintf(os.Stderr, "FAIL: assertion 1 - default cmp.Equal should distinguish nil and empty slices\n")
			os.Exit(1)
		}
		if !cmp.Equal(nilSlice, emptySlice, cmpopts.EquateEmpty()) {
			fmt.Fprintf(os.Stderr, "FAIL: assertion 1 - cmpopts.EquateEmpty should treat nil and empty slices as equal\n")
			os.Exit(1)
		}
		if diff := cmp.Diff(nilSlice, emptySlice, cmpopts.EquateEmpty()); diff != "" {
			fmt.Fprintf(os.Stderr, "FAIL: assertion 1 - unexpected diff: %s\n", diff)
			os.Exit(1)
		}
	}

	// Assertion 2: cmpopts.EquateEmpty treats nil and empty maps of the same type as equal
	{
		var nilMap map[string]int
		emptyMap := make(map[string]int)

		if cmp.Equal(nilMap, emptyMap) {
			fmt.Fprintf(os.Stderr, "FAIL: assertion 2 - default cmp.Equal should distinguish nil and empty maps\n")
			os.Exit(1)
		}
		if !cmp.Equal(nilMap, emptyMap, cmpopts.EquateEmpty()) {
			fmt.Fprintf(os.Stderr, "FAIL: assertion 2 - cmpopts.EquateEmpty should treat nil and empty maps as equal\n")
			os.Exit(1)
		}
		if diff := cmp.Diff(nilMap, emptyMap, cmpopts.EquateEmpty()); diff != "" {
			fmt.Fprintf(os.Stderr, "FAIL: assertion 2 - unexpected diff: %s\n", diff)
			os.Exit(1)
		}
	}

	// Assertion 3: cmpopts.EquateEmpty preserves inequality for non-empty slices or maps with different elements
	{
		var nilSlice []int
		nonEmptySlice := []int{1}

		if cmp.Equal(nilSlice, nonEmptySlice, cmpopts.EquateEmpty()) {
			fmt.Fprintf(os.Stderr, "FAIL: assertion 3 - cmpopts.EquateEmpty should not equate nil and non-empty slice\n")
			os.Exit(1)
		}

		sliceA := []int{1, 2}
		sliceB := []int{1, 3}
		if cmp.Equal(sliceA, sliceB, cmpopts.EquateEmpty()) {
			fmt.Fprintf(os.Stderr, "FAIL: assertion 3 - cmpopts.EquateEmpty should not equate different slices\n")
			os.Exit(1)
		}

		var nilMap map[string]int
		nonEmptyMap := map[string]int{"a": 1}
		if cmp.Equal(nilMap, nonEmptyMap, cmpopts.EquateEmpty()) {
			fmt.Fprintf(os.Stderr, "FAIL: assertion 3 - cmpopts.EquateEmpty should not equate nil and non-empty map\n")
			os.Exit(1)
		}
	}

	// Assertion 4: cmpopts.EquateEmpty equates empty slices and maps nested within structs
	{
		valA := structWithCollections{
			ID:     42,
			Labels: []string{},
			Attrs:  map[string]string{},
		}
		valB := structWithCollections{
			ID:     42,
			Labels: nil,
			Attrs:  nil,
		}

		if cmp.Equal(valA, valB) {
			fmt.Fprintf(os.Stderr, "FAIL: assertion 4 - default cmp.Equal should distinguish structs with empty vs nil collections\n")
			os.Exit(1)
		}
		if !cmp.Equal(valA, valB, cmpopts.EquateEmpty()) {
			fmt.Fprintf(os.Stderr, "FAIL: assertion 4 - cmpopts.EquateEmpty should equate structs with empty vs nil collections\n")
			os.Exit(1)
		}
		if diff := cmp.Diff(valA, valB, cmpopts.EquateEmpty()); diff != "" {
			fmt.Fprintf(os.Stderr, "FAIL: assertion 4 - unexpected diff: %s\n", diff)
			os.Exit(1)
		}
	}

	fmt.Println("PASS: cmpopts.EquateEmpty contract passed")
}