github.com/stretchr/objx v0.5.0: FromJSON

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 objx.FromJSON 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:
  - objx.FromJSON

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:sha256:8d44c1667928bb6ad13909f97ed29e2d7814b5a5905f3ea34cc45bbbba0ec358","contract":["objx.FromJSON parses a valid JSON object string into a Map","objx.FromJSON parses nested JSON structures into accessible selector paths","objx.FromJSON parses JSON arrays accessible by slice index selector","objx.FromJSON returns an error when given invalid JSON syntax","objx.FromJSON returns an error when given non-object JSON"],"goal":"verify objx.FromJSON 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":["objx.FromJSON"]},"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":["objx.FromJSON"],"verifierAdapter":"golang@1"}

module sample

go 1.22

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"
	"log"

	"github.com/stretchr/objx"
)

func main() {
	jsonString := `{
		"name": "example-service",
		"version": 1,
		"settings": {
			"enabled": true,
			"port": 8080
		},
		"tags": ["primary", "active"]
	}`

	// Parse JSON string into an objx.Map
	m, err := objx.FromJSON(jsonString)
	if err != nil {
		log.Fatalf("failed to parse JSON: %v", err)
	}

	// Access top-level fields
	name := m.Get("name").Str()
	version := m.Get("version").Int()
	fmt.Printf("Service: %s (v%d)\n", name, version)

	// Access nested fields via selector notation
	enabled := m.Get("settings.enabled").Bool()
	port := m.Get("settings.port").Int()
	fmt.Printf("Settings: enabled=%t, port=%d\n", enabled, port)

	// Access array elements via slice index selector
	firstTag := m.Get("tags[0]").Str()
	fmt.Printf("Primary tag: %s\n", firstTag)

	// Error handling for invalid JSON
	_, err = objx.FromJSON("{invalid_json")
	if err != nil {
		fmt.Println("Handled invalid JSON error successfully")
	}
}

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

package main

import (
	"fmt"
	"os"

	"github.com/stretchr/objx"
)

func main() {
	// Assertion 1: objx.FromJSON parses a valid JSON object string into a Map
	{
		raw := `{"name":"test-service","count":42,"active":true}`
		m, err := objx.FromJSON(raw)
		if err != nil {
			fmt.Fprintf(os.Stderr, "assertion 1 failed: expected nil error, got %v\n", err)
			os.Exit(1)
		}
		if m == nil {
			fmt.Fprintf(os.Stderr, "assertion 1 failed: expected non-nil Map\n")
			os.Exit(1)
		}
		if m.Get("name").Str() != "test-service" {
			fmt.Fprintf(os.Stderr, "assertion 1 failed: expected name 'test-service', got '%s'\n", m.Get("name").Str())
			os.Exit(1)
		}
		if m.Get("count").Int() != 42 {
			fmt.Fprintf(os.Stderr, "assertion 1 failed: expected count 42, got %d\n", m.Get("count").Int())
			os.Exit(1)
		}
		if !m.Get("active").Bool() {
			fmt.Fprintf(os.Stderr, "assertion 1 failed: expected active true\n")
			os.Exit(1)
		}
	}

	// Assertion 2: objx.FromJSON parses nested JSON structures into accessible selector paths
	{
		raw := `{"server":{"host":"localhost","network":{"port":8080}}}`
		m, err := objx.FromJSON(raw)
		if err != nil {
			fmt.Fprintf(os.Stderr, "assertion 2 failed: expected nil error, got %v\n", err)
			os.Exit(1)
		}
		if m.Get("server.host").Str() != "localhost" {
			fmt.Fprintf(os.Stderr, "assertion 2 failed: expected host 'localhost', got '%s'\n", m.Get("server.host").Str())
			os.Exit(1)
		}
		if m.Get("server.network.port").Int() != 8080 {
			fmt.Fprintf(os.Stderr, "assertion 2 failed: expected port 8080, got %d\n", m.Get("server.network.port").Int())
			os.Exit(1)
		}
	}

	// Assertion 3: objx.FromJSON parses JSON arrays accessible by slice index selector
	{
		raw := `{"items":["alpha","beta","gamma"]}`
		m, err := objx.FromJSON(raw)
		if err != nil {
			fmt.Fprintf(os.Stderr, "assertion 3 failed: expected nil error, got %v\n", err)
			os.Exit(1)
		}
		if m.Get("items[0]").Str() != "alpha" {
			fmt.Fprintf(os.Stderr, "assertion 3 failed: expected items[0] 'alpha', got '%s'\n", m.Get("items[0]").Str())
			os.Exit(1)
		}
		if m.Get("items[1]").Str() != "beta" {
			fmt.Fprintf(os.Stderr, "assertion 3 failed: expected items[1] 'beta', got '%s'\n", m.Get("items[1]").Str())
			os.Exit(1)
		}
		if m.Get("items[2]").Str() != "gamma" {
			fmt.Fprintf(os.Stderr, "assertion 3 failed: expected items[2] 'gamma', got '%s'\n", m.Get("items[2]").Str())
			os.Exit(1)
		}
	}

	// Assertion 4: objx.FromJSON returns an error when given invalid JSON syntax
	{
		invalidJSON := `{"name": "missing quote}`
		_, err := objx.FromJSON(invalidJSON)
		if err == nil {
			fmt.Fprintf(os.Stderr, "assertion 4 failed: expected error for invalid JSON syntax, got nil\n")
			os.Exit(1)
		}
	}

	// Assertion 5: objx.FromJSON returns an error when given non-object JSON
	{
		arrayJSON := `["item1", "item2"]`
		_, err := objx.FromJSON(arrayJSON)
		if err == nil {
			fmt.Fprintf(os.Stderr, "assertion 5 failed: expected error for JSON array, got nil\n")
			os.Exit(1)
		}

		emptyString := ``
		_, errEmpty := objx.FromJSON(emptyString)
		if errEmpty == nil {
			fmt.Fprintf(os.Stderr, "assertion 5 failed: expected error for empty string, got nil\n")
			os.Exit(1)
		}
	}

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