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

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.Get 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.Get

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:a4b0344f4470a4260525d4cfdce3ab4072bb8fc142da4a7ebf7ce3cbfe24194d","contract":["objx.Map.Get accesses nested map values using dot-separated keys","objx.Map.Get accesses array elements using index bracket notation","objx.Map.Get returns an optional default value when the selector does not match"],"goal":"verify github.com/stretchr/objx.Map.Get 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.Get"]},"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.Get"],"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{}{
		"user": map[string]interface{}{
			"name":  "Alice",
			"roles": []interface{}{"viewer", "editor"},
		},
	})

	name := m.Get("user.name").Str()
	role := m.Get("user.roles[1]").Str()
	missing := m.Get("user.email").Str("none@example.com")

	fmt.Printf("Name: %s, Role: %s, Missing: %s\n", name, role, missing)
}

{
  "schemaVersion": 1,
  "goal": "verify github.com/stretchr/objx.Map.Get 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.Get"
  ]
}

package main

import (
	"fmt"
	"os"

	"github.com/stretchr/objx"
)

func main() {
	m := objx.New(map[string]interface{}{
		"user": map[string]interface{}{
			"name":  "Alice",
			"roles": []interface{}{"viewer", "editor"},
		},
	})

	// Assertion 1: objx.Map.Get accesses nested map values using dot-separated keys
	if got := m.Get("user.name").Str(); got != "Alice" {
		fmt.Fprintf(os.Stderr, "contract assertion 1 failed: expected %q, got %q\n", "Alice", got)
		os.Exit(1)
	}

	// Assertion 2: objx.Map.Get accesses array elements using index bracket notation
	if got := m.Get("user.roles[1]").Str(); got != "editor" {
		fmt.Fprintf(os.Stderr, "contract assertion 2 failed: expected %q, got %q\n", "editor", got)
		os.Exit(1)
	}

	// Assertion 3: objx.Map.Get returns an optional default value when the selector does not match
	if got := m.Get("user.email").Str("fallback"); got != "fallback" {
		fmt.Fprintf(os.Stderr, "contract assertion 3 failed: expected %q, got %q\n", "fallback", got)
		os.Exit(1)
	}

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