github.com/google/go-cmp v0.5.7: cmp.Options

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.Options in pkg:golang/github.com/google/go-cmp@v0.5.7
Kind: HOW

Use EXACTLY these public packages and versions:
  - pkg:golang/github.com/google/go-cmp@v0.5.7
Demonstrate these symbols/APIs:
  - github.com/google/go-cmp/cmp.Options

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:e0d26509cad18fe8c12f959709620fb22ff599bd4fa019f0a64e9e36009c743a","contract":["cmp.Options implements cmp.Option and groups multiple comparison options into a single option value","cmp.Options applies all contained options during cmp.Equal and cmp.Diff","cmp.Options supports nested cmp.Options slices to compose option bundles hierarchically","empty cmp.Options acts as a no-op cmp.Option preserving standard equality semantics"],"goal":"verify github.com/google/go-cmp/cmp.Options in pkg:golang/github.com/google/go-cmp@v0.5.7","kind":"HOW","packages":["pkg:golang/github.com/google/go-cmp@v0.5.7"],"schemaVersion":1,"symbols":["github.com/google/go-cmp/cmp.Options"]},"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@v0.5.7"],"schemaVersion":1,"subject":"pkg:golang/github.com/google/go-cmp@v0.5.7","symbols":["github.com/google/go-cmp/cmp.Options"],"verifierAdapter":"golang@1"}

module sample

go 1.22.0

require github.com/google/go-cmp v0.5.7

github.com/google/go-cmp v0.5.7 h1:81/ik6ipDQS2aGcBfIN5dHDB36BwrStyeAQquSYCV4o=
github.com/google/go-cmp v0.5.7/go.mod h1:n+brtR0CgQNWTVd5ZUFpTBC8YFBDLK/h/bpaJ8/DtOE=
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"
	"math"
	"strings"

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

type Endpoint struct {
	Host    string
	Latency float64
	Active  bool
}

func main() {
	bundle := cmp.Options{
		cmp.Transformer("LowerHost", strings.ToLower),
		cmp.Comparer(func(a, b float64) bool {
			return math.Abs(a-b) < 1e-3
		}),
	}

	left := Endpoint{Host: "API.EXAMPLE.COM", Latency: 12.5001, Active: true}
	right := Endpoint{Host: "api.example.com", Latency: 12.5004, Active: true}

	if cmp.Equal(left, right, bundle) {
		fmt.Println("Endpoints match using cmp.Options.")
	} else {
		fmt.Println("Endpoints do not match.")
	}
}

{
  "schemaVersion": 1,
  "goal": "verify github.com/google/go-cmp/cmp.Options in pkg:golang/github.com/google/go-cmp@v0.5.7",
  "kind": "HOW",
  "packages": [
    "pkg:golang/github.com/google/go-cmp@v0.5.7"
  ],
  "symbols": [
    "github.com/google/go-cmp/cmp.Options"
  ]
}

package main

import (
	"fmt"
	"math"
	"os"
	"strings"

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

type SampleRecord struct {
	Label  string
	Metric float64
	Meta   string
}

func main() {
	// 1. cmp.Options implements cmp.Option and groups multiple comparison options into a single option value
	{
		normLabel := cmp.Transformer("UpperLabel", strings.ToUpper)
		approxMetric := cmp.Comparer(func(x, y float64) bool {
			return math.Abs(x-y) < 1e-3
		})

		var combined cmp.Option = cmp.Options{normLabel, approxMetric}
		if combined == nil {
			fmt.Fprintln(os.Stderr, "contract 1 failed: cmp.Options as cmp.Option was nil")
			os.Exit(1)
		}

		a := SampleRecord{Label: "alpha", Metric: 5.0001, Meta: "v1"}
		b := SampleRecord{Label: "ALPHA", Metric: 5.0005, Meta: "v1"}
		if !cmp.Equal(a, b, combined) {
			fmt.Fprintln(os.Stderr, "contract 1 failed: expected equal with combined cmp.Options")
			os.Exit(1)
		}
	}

	// 2. cmp.Options applies all contained options during cmp.Equal and cmp.Diff
	{
		ignoreMeta := cmp.FilterPath(func(p cmp.Path) bool {
			return p.Last().String() == ".Meta"
		}, cmp.Ignore())
		trimLabel := cmp.Transformer("TrimLabel", strings.TrimSpace)

		opts := cmp.Options{ignoreMeta, trimLabel}

		a := SampleRecord{Label: "  node-1  ", Metric: 42.0, Meta: "first"}
		b := SampleRecord{Label: "node-1", Metric: 42.0, Meta: "second"}
		c := SampleRecord{Label: "node-2", Metric: 42.0, Meta: "first"}

		if !cmp.Equal(a, b, opts) {
			fmt.Fprintln(os.Stderr, "contract 2 failed: expected a and b to match under opts")
			os.Exit(1)
		}
		if diff := cmp.Diff(a, b, opts); diff != "" {
			fmt.Fprintf(os.Stderr, "contract 2 failed: expected empty diff, got %q\n", diff)
			os.Exit(1)
		}
		if cmp.Equal(a, c, opts) {
			fmt.Fprintln(os.Stderr, "contract 2 failed: expected a and c to differ")
			os.Exit(1)
		}
	}

	// 3. cmp.Options supports nested cmp.Options slices to compose option bundles hierarchically
	{
		stringOpts := cmp.Options{
			cmp.Transformer("CaseFold", strings.ToLower),
		}
		floatOpts := cmp.Options{
			cmp.Comparer(func(x, y float64) bool {
				return math.Abs(x-y) < 0.01
			}),
		}
		nested := cmp.Options{stringOpts, floatOpts}

		a := SampleRecord{Label: "ServiceA", Metric: 100.002, Meta: "ok"}
		b := SampleRecord{Label: "servicea", Metric: 100.008, Meta: "ok"}

		if !cmp.Equal(a, b, nested) {
			fmt.Fprintln(os.Stderr, "contract 3 failed: expected nested cmp.Options to apply all nested options")
			os.Exit(1)
		}
	}

	// 4. An empty cmp.Options{} acts as a no-op cmp.Option that preserves standard equality semantics
	{
		empty := cmp.Options{}

		a := SampleRecord{Label: "exact", Metric: 1.5, Meta: "m"}
		b := SampleRecord{Label: "exact", Metric: 1.5, Meta: "m"}
		c := SampleRecord{Label: "exact", Metric: 2.5, Meta: "m"}

		if !cmp.Equal(a, b, empty) {
			fmt.Fprintln(os.Stderr, "contract 4 failed: expected identical values to be equal with empty cmp.Options")
			os.Exit(1)
		}
		if cmp.Equal(a, c, empty) {
			fmt.Fprintln(os.Stderr, "contract 4 failed: expected distinct values to be unequal with empty cmp.Options")
			os.Exit(1)
		}
	}

	fmt.Println("All contract assertions passed.")
}