github.com/stretchr/objx v0.4.0

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/stretchr/objx@v0.4.0
Kind: HOW

Use EXACTLY these public packages and versions:
  - pkg:golang/github.com/stretchr/objx@v0.4.0

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:sha256:63dc29439c2fbdddbf131f053f6befcf254059173a858cd9ab231a9c44455941","contract":["objx.FromJSON parses a JSON object into an objx.Map and accesses top-level fields","objx.Map.Get traverses nested objects and slice indices using selector syntax","objx.Map.Set and objx.Map.Has mutate and inspect nested keys","objx.Map.JSON serializes the map back into a JSON string and FromJSON round-trips it","objx.FromJSON returns an error for invalid JSON input"],"goal":"verify pkg:golang/github.com/stretchr/objx@v0.4.0","kind":"HOW","packages":["pkg:golang/github.com/stretchr/objx@v0.4.0"],"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/stretchr/objx@v0.4.0"],"schemaVersion":1,"subject":"pkg:golang/github.com/stretchr/objx@v0.4.0","verifierAdapter":"golang@1"}

module sample

go 1.22

require github.com/stretchr/objx v0.4.0

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/pmezard/go-difflib v1.0.0 h1:4DBwDE0NGyQoBHbLQYPwSUPoCMWR5BEzIk/f1lZbAQM=
github.com/pmezard/go-difflib v1.0.0/go.mod h1:iKH77koFhYxTK1pcRnkKkqfTogsbg7gZNVY4sRDYZ/4=
github.com/stretchr/objx v0.1.0/go.mod h1:HFkY916IF+rwdDfMAkV7OtwuqBVzrE8GR6GFx+wExME=
github.com/stretchr/objx v0.4.0 h1:M2gUjqZET1qApGOWNSnZ49BAIMX4F/1plDv3+l31EJ4=
github.com/stretchr/objx v0.4.0/go.mod h1:YvHI0jy2hoMjB+UWwv71VJQ9isScKT/TqJzVSSt89Yw=
github.com/stretchr/testify v1.7.1 h1:5TQK59W5E3v0r2duFAb7P95B6hEeOyEnHRa8MjYSMTY=
github.com/stretchr/testify v1.7.1/go.mod h1:6Fq8oRcR53rry900zMqJjRRixrwX3KX962/h/Wwjteg=
gopkg.in/check.v1 v0.0.0-20161208181325-20d25e280405/go.mod h1:Co6ibVJAznAaIkqp8huTwlJQCZ016jof/cbN4VW5Yz0=
gopkg.in/yaml.v3 v3.0.0-20200313102051-9f266ea9e77c h1:dUUwHk2QECo/6vqA44rthZ8ie2QXMNeKRTHCNY2nXvo=
gopkg.in/yaml.v3 v3.0.0-20200313102051-9f266ea9e77c/go.mod h1:K4uyk7z7BCEPqu6E+C64Yfv1cQ7kz7rIZviUmN+EgEM=

package main

import (
	"fmt"
	"log"

	"github.com/stretchr/objx"
)

func main() {
	raw := `{"service":"gateway","port":8080,"routes":[{"path":"/health","enabled":true}]}`

	m, err := objx.FromJSON(raw)
	if err != nil {
		log.Fatalf("unexpected error: %v", err)
	}

	m.Set("routes[0].timeout", 30)

	fmt.Printf("service=%s port=%d path=%s enabled=%t timeout=%d\n",
		m.Get("service").Str(),
		m.Get("port").Int(),
		m.Get("routes[0].path").Str(),
		m.Get("routes[0].enabled").Bool(),
		m.Get("routes[0].timeout").Int(),
	)
}

{
  "schemaVersion": 1,
  "goal": "verify pkg:golang/github.com/stretchr/objx@v0.4.0",
  "kind": "HOW",
  "packages": [
    "pkg:golang/github.com/stretchr/objx@v0.4.0"
  ]
}

package main

import (
	"fmt"
	"os"

	"github.com/stretchr/objx"
)

func main() {
	// Assertion 1: objx.FromJSON parses a JSON object into an objx.Map and accesses top-level fields
	{
		raw := `{"name":"worker","threads":4,"active":true}`
		m, err := objx.FromJSON(raw)
		if err != nil {
			fmt.Fprintf(os.Stderr, "assertion 1 failed: unexpected error: %v\n", err)
			os.Exit(1)
		}
		if m.Get("name").Str() != "worker" || m.Get("threads").Int() != 4 || !m.Get("active").Bool() {
			fmt.Fprintf(os.Stderr, "assertion 1 failed: unexpected field values\n")
			os.Exit(1)
		}
	}

	// Assertion 2: objx.Map.Get traverses nested objects and slice indices using selector syntax
	{
		raw := `{"config":{"endpoints":["http://localhost:8000","http://localhost:8001"]}}`
		m, err := objx.FromJSON(raw)
		if err != nil {
			fmt.Fprintf(os.Stderr, "assertion 2 failed: unexpected error: %v\n", err)
			os.Exit(1)
		}
		if m.Get("config.endpoints[1]").Str() != "http://localhost:8001" {
			fmt.Fprintf(os.Stderr, "assertion 2 failed: unexpected endpoint value\n")
			os.Exit(1)
		}
	}

	// Assertion 3: objx.Map.Set and objx.Map.Has mutate and inspect nested keys
	{
		m := objx.New(map[string]interface{}{
			"database": map[string]interface{}{
				"host": "localhost",
			},
		})
		if !m.Has("database.host") || m.Has("database.port") {
			fmt.Fprintf(os.Stderr, "assertion 3 failed: unexpected initial Has result\n")
			os.Exit(1)
		}
		m.Set("database.port", 5432)
		if !m.Has("database.port") || m.Get("database.port").Int() != 5432 {
			fmt.Fprintf(os.Stderr, "assertion 3 failed: Set did not update nested key\n")
			os.Exit(1)
		}
	}

	// Assertion 4: objx.Map.JSON serializes the map back into a JSON string and FromJSON round-trips it
	{
		m := objx.New(map[string]interface{}{"status": "ok", "code": 200})
		encoded, err := m.JSON()
		if err != nil {
			fmt.Fprintf(os.Stderr, "assertion 4 failed: JSON error: %v\n", err)
			os.Exit(1)
		}
		decoded, err := objx.FromJSON(encoded)
		if err != nil || decoded.Get("status").Str() != "ok" || decoded.Get("code").Int() != 200 {
			fmt.Fprintf(os.Stderr, "assertion 4 failed: round-trip mismatch\n")
			os.Exit(1)
		}
	}

	// Assertion 5: objx.FromJSON returns an error for invalid JSON input
	{
		if _, err := objx.FromJSON("{invalid"); err == nil {
			fmt.Fprintf(os.Stderr, "assertion 5 failed: expected error on invalid JSON\n")
			os.Exit(1)
		}
	}

	fmt.Println("contract ok")
}