github.com/stretchr/objx v0.2.0: New

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.New in pkg:golang/github.com/stretchr/objx@v0.2.0
Kind: HOW

Use EXACTLY these public packages and versions:
  - pkg:golang/github.com/stretchr/objx@v0.2.0
Demonstrate these symbols/APIs:
  - github.com/stretchr/objx.New

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:sha256:414c7307df529eef7eeff543e1b0e88b001126ac4bbde94b4e6ae90cf3bd8ea0","contract":["objx.New wraps a map[string]interface{} into an objx.Map with direct key access and mutability","objx.New converts types implementing MSIConvertable into an objx.Map","objx.New returns nil when given nil, unsupported primitive types, or unconvertable structs"],"goal":"verify github.com/stretchr/objx.New in pkg:golang/github.com/stretchr/objx@v0.2.0","kind":"HOW","packages":["pkg:golang/github.com/stretchr/objx@v0.2.0"],"schemaVersion":1,"symbols":["github.com/stretchr/objx.New"]},"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@v0.2.0"],"schemaVersion":1,"subject":"pkg:golang/github.com/stretchr/objx@v0.2.0","symbols":["github.com/stretchr/objx.New"],"verifierAdapter":"golang@1"}

module sample

go 1.22

require github.com/stretchr/objx v0.2.0

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 v0.2.0 h1:Hbg2NidpLE8veEBkEZTL3CvlkUIVzuU9jDplZO54c48=
github.com/stretchr/objx v0.2.0/go.mod h1:qt09Ya8vawLte6SNmTgCsAVtYtaKzEcn8ATUoHMkEqE=
github.com/stretchr/testify v1.3.0 h1:TivCn/peBQ7UY8ooIcPgZFpTNSz0Q2U6UrFlUfqbe0Q=
github.com/stretchr/testify v1.3.0/go.mod h1:M5WIy9Dh21IEIfnGCwXGc5bZfKNJtfHm1UVUgZn+9EI=

package main

import (
	"fmt"

	"github.com/stretchr/objx"
)

// serviceConfig implements objx.MSIConvertable to support objx.New conversion.
type serviceConfig struct {
	endpoint string
	port     int
}

func (s *serviceConfig) MSI() map[string]interface{} {
	return map[string]interface{}{
		"endpoint": s.endpoint,
		"port":     s.port,
	}
}

func main() {
	// 1. Wrap a standard map[string]interface{} into an objx.Map
	data := map[string]interface{}{
		"service": "database",
		"retries": 3,
	}
	m := objx.New(data)
	fmt.Printf("Service: %v, Retries: %v\n", m.Get("service").Str(), m.Get("retries").Int())

	// 2. Convert an MSIConvertable type into an objx.Map
	cfg := &serviceConfig{endpoint: "localhost", port: 8080}
	cfgMap := objx.New(cfg)
	fmt.Printf("Endpoint: %v, Port: %v\n", cfgMap.Get("endpoint").Str(), cfgMap.Get("port").Int())

	// 3. Non-convertable or nil inputs return nil
	nilMap := objx.New(nil)
	fmt.Printf("objx.New(nil) == nil: %t\n", nilMap == nil)
}

{
  "schemaVersion": 1,
  "goal": "verify github.com/stretchr/objx.New in pkg:golang/github.com/stretchr/objx@v0.2.0",
  "kind": "HOW",
  "packages": [
    "pkg:golang/github.com/stretchr/objx@v0.2.0"
  ],
  "symbols": [
    "github.com/stretchr/objx.New"
  ]
}

package main

import (
	"fmt"
	"os"

	"github.com/stretchr/objx"
)

type customData struct {
	key   string
	value int
}

func (c *customData) MSI() map[string]interface{} {
	return map[string]interface{}{
		"key":   c.key,
		"value": c.value,
	}
}

type unconvertableData struct {
	key string
}

func main() {
	// Assertion 1: objx.New wraps an existing map[string]interface{} into an objx.Map allowing map access and mutations
	{
		data := map[string]interface{}{
			"name":   "widget",
			"count":  10,
			"active": true,
		}
		m := objx.New(data)
		if m == nil {
			fmt.Fprintf(os.Stderr, "assertion 1 failed: expected non-nil Map\n")
			os.Exit(1)
		}
		if m["name"] != "widget" || m["count"] != 10 || m["active"] != true {
			fmt.Fprintf(os.Stderr, "assertion 1 failed: key values do not match\n")
			os.Exit(1)
		}
		// Mutations to objx.Map affect the underlying map
		m["count"] = 20
		if data["count"] != 20 {
			fmt.Fprintf(os.Stderr, "assertion 1 failed: underlying map should reflect mutation\n")
			os.Exit(1)
		}
	}

	// Assertion 2: objx.New converts types implementing MSIConvertable by calling their MSI method
	{
		obj := &customData{key: "setting", value: 100}
		m := objx.New(obj)
		if m == nil {
			fmt.Fprintf(os.Stderr, "assertion 2 failed: expected non-nil Map from MSIConvertable\n")
			os.Exit(1)
		}
		if m["key"] != "setting" || m["value"] != 100 {
			fmt.Fprintf(os.Stderr, "assertion 2 failed: converted values mismatch\n")
			os.Exit(1)
		}
	}

	// Assertion 3: objx.New returns nil when input is nil, an unconvertable struct, or an unsupported primitive type
	{
		if m := objx.New(nil); m != nil {
			fmt.Fprintf(os.Stderr, "assertion 3 failed: objx.New(nil) must be nil\n")
			os.Exit(1)
		}
		if m := objx.New("invalid_string"); m != nil {
			fmt.Fprintf(os.Stderr, "assertion 3 failed: objx.New(string) must be nil\n")
			os.Exit(1)
		}
		if m := objx.New(12345); m != nil {
			fmt.Fprintf(os.Stderr, "assertion 3 failed: objx.New(int) must be nil\n")
			os.Exit(1)
		}
		if m := objx.New(&unconvertableData{key: "test"}); m != nil {
			fmt.Fprintf(os.Stderr, "assertion 3 failed: objx.New(unconvertable) must be nil\n")
			os.Exit(1)
		}
	}

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