github.com/stretchr/objx v0.5.0: Map.JSON

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.Map.JSON in pkg:golang/github.com/stretchr/objx@v0.5.0
Kind: HOW

Use EXACTLY these public packages and versions:
  - pkg:golang/github.com/stretchr/objx@v0.5.0
Demonstrate these symbols/APIs:
  - github.com/stretchr/objx.Map.JSON

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:sha256:41363fb389d6c3536309817e68ca0635f42fb0cc22c6722e4956057a888a2a5a","contract":["objx.Map.JSON serializes a map to a valid JSON string","objx.Map.JSON preserves nested maps and slice elements in the JSON output","objx.Map.JSON returns an error when the map contains values that cannot be marshaled to JSON"],"goal":"verify github.com/stretchr/objx.Map.JSON in pkg:golang/github.com/stretchr/objx@v0.5.0","kind":"HOW","packages":["pkg:golang/github.com/stretchr/objx@v0.5.0"],"schemaVersion":1,"symbols":["github.com/stretchr/objx.Map.JSON"]},"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@v0.5.0"],"schemaVersion":1,"subject":"pkg:golang/github.com/stretchr/objx@v0.5.0","symbols":["github.com/stretchr/objx.Map.JSON"],"verifierAdapter":"golang@1"}

module example.com/sample

go 1.26.6

require github.com/stretchr/objx v0.5.0

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/go.mod h1:YvHI0jy2hoMjB+UWwv71VJQ9isScKT/TqJzVSSt89Yw=
github.com/stretchr/objx v0.5.0 h1:1zr/of2m5FGMsad5YfcqgdqdWrIhu+EBEJRhR1U7z/c=
github.com/stretchr/objx v0.5.0/go.mod h1:Yh+to48EsGEfYuaHDzXPcE3xhTkx73EhmCGUpEOglKo=
github.com/stretchr/testify v1.7.1/go.mod h1:6Fq8oRcR53rry900zMqJjRRixrwX3KX962/h/Wwjteg=
github.com/stretchr/testify v1.8.0 h1:pSgiaMZlXftHpm5L7V1+rVB+AZJydKsMxsQBIJw4PKk=
github.com/stretchr/testify v1.8.0/go.mod h1:yNjHg4UonilssWZ8iaSj1OCr/vHnekPRkoO+kdMU+MU=
gopkg.in/check.v1 v0.0.0-20161208181325-20d25e280405/go.mod h1:Co6ibVJAznAaIkqp8huTwlJQCZ016jof/cbN4VW5Yz0=
gopkg.in/yaml.v3 v3.0.0-20200313102051-9f266ea9e77c/go.mod h1:K4uyk7z7BCEPqu6E+C64Yfv1cQ7kz7rIZviUmN+EgEM=
gopkg.in/yaml.v3 v3.0.1 h1:fxVm/GzAzEWqLHuvctI91KS9hhNmmWOoWu0XTYJS7CA=
gopkg.in/yaml.v3 v3.0.1/go.mod h1:K4uyk7z7BCEPqu6E+C64Yfv1cQ7kz7rIZviUmN+EgEM=

package main

import (
	"fmt"

	"github.com/stretchr/objx"
)

func main() {
	m := objx.New(map[string]interface{}{
		"name":   "Alice",
		"config": map[string]interface{}{"timeout": 30},
		"active": true,
	})

	jsonStr, err := m.JSON()
	if err != nil {
		panic(err)
	}

	fmt.Println(jsonStr)
}

{
  "schemaVersion": 1,
  "goal": "verify github.com/stretchr/objx.Map.JSON in pkg:golang/github.com/stretchr/objx@v0.5.0",
  "kind": "HOW",
  "packages": [
    "pkg:golang/github.com/stretchr/objx@v0.5.0"
  ],
  "symbols": [
    "github.com/stretchr/objx.Map.JSON"
  ]
}

package main

import (
	"encoding/json"
	"fmt"
	"math"
	"os"

	"github.com/stretchr/objx"
)

func main() {
	// Assertion 1: objx.Map.JSON serializes a map to a valid JSON string
	m1 := objx.New(map[string]interface{}{
		"name":   "Alice",
		"active": true,
	})
	jsonStr1, err1 := m1.JSON()
	if err1 != nil {
		fmt.Fprintf(os.Stderr, "contract assertion 1 failed: unexpected error: %v\n", err1)
		os.Exit(1)
	}
	var parsed1 map[string]interface{}
	if err := json.Unmarshal([]byte(jsonStr1), &parsed1); err != nil {
		fmt.Fprintf(os.Stderr, "contract assertion 1 failed: unmarshal error: %v\n", err)
		os.Exit(1)
	}
	if parsed1["name"] != "Alice" || parsed1["active"] != true {
		fmt.Fprintf(os.Stderr, "contract assertion 1 failed: unexpected values: %v\n", parsed1)
		os.Exit(1)
	}

	// Assertion 2: objx.Map.JSON preserves nested maps and slice elements in the JSON output
	m2 := objx.New(map[string]interface{}{
		"server": map[string]interface{}{
			"host": "localhost",
			"port": 8080,
		},
		"tags": []interface{}{"api", "auth"},
	})
	jsonStr2, err2 := m2.JSON()
	if err2 != nil {
		fmt.Fprintf(os.Stderr, "contract assertion 2 failed: unexpected error: %v\n", err2)
		os.Exit(1)
	}
	var parsed2 map[string]interface{}
	if err := json.Unmarshal([]byte(jsonStr2), &parsed2); err != nil {
		fmt.Fprintf(os.Stderr, "contract assertion 2 failed: unmarshal error: %v\n", err)
		os.Exit(1)
	}
	server, ok := parsed2["server"].(map[string]interface{})
	if !ok || server["host"] != "localhost" || server["port"] != float64(8080) {
		fmt.Fprintf(os.Stderr, "contract assertion 2 failed: nested map mismatch: %v\n", parsed2)
		os.Exit(1)
	}
	tags, ok := parsed2["tags"].([]interface{})
	if !ok || len(tags) != 2 || tags[0] != "api" || tags[1] != "auth" {
		fmt.Fprintf(os.Stderr, "contract assertion 2 failed: slice mismatch: %v\n", parsed2)
		os.Exit(1)
	}

	// Assertion 3: objx.Map.JSON returns an error when the map contains values that cannot be marshaled to JSON
	m3 := objx.New(map[string]interface{}{
		"invalid": math.NaN(),
	})
	_, err3 := m3.JSON()
	if err3 == nil {
		fmt.Fprintf(os.Stderr, "contract assertion 3 failed: expected error for unmarshalable float, got nil\n")
		os.Exit(1)
	}

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