github.com/stretchr/objx v0.1.0: Map.Merge

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.Merge in pkg:golang/github.com/stretchr/objx@v0.1.0
Kind: HOW

Use EXACTLY these public packages and versions:
  - pkg:golang/github.com/stretchr/objx@v0.1.0
Demonstrate these symbols/APIs:
  - github.com/stretchr/objx.Map.Merge
Constraints:
  - executionContext: node
Required runtime conditions:
  - ecosystem: npm
  - language: javascript
  - moduleSystem: cjs
  - packageManager: npm@10.9.8
  - runtime: node@22.23.2

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:db95006159a4944bbb71add4e989d9d609cde9c86e183ed794282e55bd57e1ca","contract":["objx.Map.Merge returns a new Map containing key-value pairs from both maps","objx.Map.Merge overwrites existing receiver keys with values from the specified map","objx.Map.Merge preserves the original receiver map and argument map without mutation","objx.Map.Merge with an empty or nil map returns a copy containing the receiver entries"],"goal":"verify github.com/stretchr/objx.Map.Merge in pkg:golang/github.com/stretchr/objx@v0.1.0","kind":"HOW","packages":["pkg:golang/github.com/stretchr/objx@v0.1.0"],"schemaVersion":1,"symbols":["github.com/stretchr/objx.Map.Merge"]},"contractCommand":["go","run","./test"],"environment":{"arch":"x64","distro":"ubuntu","ecosystem":"golang","language":"go","libc":"glibc","libcVersion":"2.39","os":"linux","osVersionBucket":"24","packageManager":"go","packageManagerVersion":"1.26.6","runtime":"go","runtimeVersion":"1.26.6","schemaVersion":1},"license":"MIT-0","packages":["pkg:golang/github.com/stretchr/objx@v0.1.0"],"schemaVersion":1,"subject":"pkg:golang/github.com/stretchr/objx@v0.1.0","symbols":["github.com/stretchr/objx.Map.Merge"],"verifierAdapter":"golang@1"}

module example.com/sample

go 1.26.6

require github.com/stretchr/objx v0.1.0

github.com/stretchr/objx v0.1.0 h1:4G4v2dO3VZwixGIRoQ5Lfboy6nUhCyYzaqnIAPPhYs4=
github.com/stretchr/objx v0.1.0/go.mod h1:HFkY916IF+rwdDfMAkV7OtwuqBVzrE8GR6GFx+wExME=

package main

import (
	"fmt"

	"github.com/stretchr/objx"
)

func main() {
	// Base configuration map
	baseConfig := objx.New(map[string]interface{}{
		"host":    "localhost",
		"port":    8080,
		"timeout": 30,
		"debug":   false,
	})

	// Override configuration map
	overrides := objx.New(map[string]interface{}{
		"port":    9090,
		"debug":   true,
		"profile": "staging",
	})

	// Merge creates a new Map with values blended, overrides taking precedence
	merged := baseConfig.Merge(overrides)

	fmt.Printf("Base port: %v, debug: %v\n", baseConfig.Get("port").Data(), baseConfig.Get("debug").Data())
	fmt.Printf("Merged port: %v, debug: %v, host: %v, profile: %v\n",
		merged.Get("port").Data(),
		merged.Get("debug").Data(),
		merged.Get("host").Data(),
		merged.Get("profile").Data(),
	)
}

{
  "schemaVersion": 1,
  "goal": "verify github.com/stretchr/objx.Map.Merge in pkg:golang/github.com/stretchr/objx@v0.1.0",
  "kind": "HOW",
  "packages": [
    "pkg:golang/github.com/stretchr/objx@v0.1.0"
  ],
  "symbols": [
    "github.com/stretchr/objx.Map.Merge"
  ],
  "constraints": {
    "executionContext": "node"
  },
  "runtimeConditions": {
    "ecosystem": "npm",
    "language": "javascript",
    "moduleSystem": "cjs",
    "packageManager": "npm@10.9.8",
    "runtime": "node@22.23.2"
  }
}

package main

import (
	"fmt"
	"os"

	"github.com/stretchr/objx"
)

func main() {
	// Assertion 1: objx.Map.Merge returns a new Map containing key-value pairs from both maps
	{
		m1 := objx.New(map[string]interface{}{"host": "localhost", "port": 8080})
		m2 := objx.New(map[string]interface{}{"service": "auth"})
		merged := m1.Merge(m2)

		if merged.Get("host").Str() != "localhost" || merged.Get("port").Int() != 8080 || merged.Get("service").Str() != "auth" {
			fmt.Fprintf(os.Stderr, "assertion 1 failed: merged map missing expected key-value pairs\n")
			os.Exit(1)
		}
	}

	// Assertion 2: objx.Map.Merge overwrites existing receiver keys with values from the specified map
	{
		m1 := objx.New(map[string]interface{}{"env": "development", "timeout": 30})
		m2 := objx.New(map[string]interface{}{"env": "production", "retries": 3})
		merged := m1.Merge(m2)

		if merged.Get("env").Str() != "production" || merged.Get("timeout").Int() != 30 || merged.Get("retries").Int() != 3 {
			fmt.Fprintf(os.Stderr, "assertion 2 failed: duplicate keys should be overwritten by the argument map\n")
			os.Exit(1)
		}
	}

	// Assertion 3: objx.Map.Merge preserves the original receiver map and argument map without mutation
	{
		orig1 := map[string]interface{}{"a": 1, "b": 2}
		orig2 := map[string]interface{}{"b": 99, "c": 3}
		m1 := objx.New(orig1)
		m2 := objx.New(orig2)

		_ = m1.Merge(m2)

		if m1.Get("b").Int() != 2 || m1.Has("c") {
			fmt.Fprintf(os.Stderr, "assertion 3 failed: receiver map was mutated by Merge\n")
			os.Exit(1)
		}
		if m2.Get("b").Int() != 99 || m2.Has("a") {
			fmt.Fprintf(os.Stderr, "assertion 3 failed: argument map was mutated by Merge\n")
			os.Exit(1)
		}
	}

	// Assertion 4: objx.Map.Merge with an empty or nil map returns a copy containing the receiver entries
	{
		m := objx.New(map[string]interface{}{"active": true, "count": 10})
		emptyMap := objx.New(map[string]interface{}{})
		var nilMap objx.Map

		mergedWithEmpty := m.Merge(emptyMap)
		if mergedWithEmpty.Get("active").Bool() != true || mergedWithEmpty.Get("count").Int() != 10 {
			fmt.Fprintf(os.Stderr, "assertion 4 failed: merging with empty map failed\n")
			os.Exit(1)
		}

		mergedWithNil := m.Merge(nilMap)
		if mergedWithNil.Get("active").Bool() != true || mergedWithNil.Get("count").Int() != 10 {
			fmt.Fprintf(os.Stderr, "assertion 4 failed: merging with nil map failed\n")
			os.Exit(1)
		}
	}

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