github.com/stretchr/objx v0.5.3: MustFromJSON

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/stretchr/objx.MustFromJSON in pkg:golang/github.com/stretchr/objx@v0.5.3
Kind: HOW

Use EXACTLY these public packages and versions:
  - pkg:golang/github.com/stretchr/objx@v0.5.3
Demonstrate these symbols/APIs:
  - github.com/stretchr/objx.MustFromJSON

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:a41bb682f1a10f3fb086685b75b2af86923a652edccbe709967c8b181b495631","contract":["objx.MustFromJSON parses a valid JSON object string into an objx.Map and supports nested path and slice index lookup via Get","objx.MustFromJSON panics when called with a malformed JSON string"],"goal":"verify github.com/stretchr/objx.MustFromJSON in pkg:golang/github.com/stretchr/objx@v0.5.3","kind":"HOW","packages":["pkg:golang/github.com/stretchr/objx@v0.5.3"],"schemaVersion":1,"symbols":["github.com/stretchr/objx.MustFromJSON"]},"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@v0.5.3"],"schemaVersion":1,"subject":"pkg:golang/github.com/stretchr/objx@v0.5.3","symbols":["github.com/stretchr/objx.MustFromJSON"],"verifierAdapter":"golang@1"}

module sample

go 1.21

require github.com/stretchr/objx v0.5.3

github.com/stretchr/objx v0.5.3 h1:jmXUvGomnU1o3W/V5h2VEradbpJDwGrzugQQvL0POH4=
github.com/stretchr/objx v0.5.3/go.mod h1:rDQraq+vQZU7Fde9LOZLr8Tax6zZvy4kuNKF+QYS+U0=

package main

import (
	"fmt"

	"github.com/stretchr/objx"
)

func ParseConfig(rawJSON string) objx.Map {
	return objx.MustFromJSON(rawJSON)
}

func main() {
	m := ParseConfig(`{"service":{"name":"api","port":8080},"tags":["v1","prod"]}`)
	fmt.Println(m.Get("service.name").Str(), m.Get("service.port").Int())
}

{
  "schemaVersion": 1,
  "goal": "verify github.com/stretchr/objx.MustFromJSON in pkg:golang/github.com/stretchr/objx@v0.5.3",
  "kind": "HOW",
  "packages": [
    "pkg:golang/github.com/stretchr/objx@v0.5.3"
  ],
  "symbols": [
    "github.com/stretchr/objx.MustFromJSON"
  ]
}

package main

import (
	"fmt"
	"os"

	"github.com/stretchr/objx"
)

func main() {
	m := objx.MustFromJSON(`{"config":{"mode":"strict","retries":3},"items":["alpha","beta"],"enabled":true}`)

	if got := m.Get("config.mode").Str(); got != "strict" {
		fmt.Fprintf(os.Stderr, "expected config.mode = strict, got %q\n", got)
		os.Exit(1)
	}
	if got := m.Get("config.retries").Int(); got != 3 {
		fmt.Fprintf(os.Stderr, "expected config.retries = 3, got %d\n", got)
		os.Exit(1)
	}
	if got := m.Get("items[1]").Str(); got != "beta" {
		fmt.Fprintf(os.Stderr, "expected items[1] = beta, got %q\n", got)
		os.Exit(1)
	}
	if got := m.Get("enabled").Bool(); !got {
		fmt.Fprintf(os.Stderr, "expected enabled = true, got %v\n", got)
		os.Exit(1)
	}

	panicked := false
	func() {
		defer func() {
			if r := recover(); r != nil {
				panicked = true
			}
		}()
		_ = objx.MustFromJSON(`{invalid json`)
	}()
	if !panicked {
		fmt.Fprintln(os.Stderr, "expected MustFromJSON to panic on invalid JSON")
		os.Exit(1)
	}
}