github.com/rs/zerolog v1.15.0: 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/rs/zerolog.New in pkg:golang/github.com/rs/zerolog@v1.15.0
Kind: HOW

Use EXACTLY these public packages and versions:
  - pkg:golang/github.com/rs/zerolog@v1.15.0
Demonstrate these symbols/APIs:
  - github.com/rs/zerolog.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:af52b1dc0af48005375fe1474d62893973dff42938ed878c95c8b2041dcd96ae","contract":["zerolog.New creates a Logger writing structured JSON to an io.Writer","zerolog.New writes log events formatted with message and level","zerolog.New with nil writer creates a Logger that safely discards log output","zerolog.New logger formats structured key-value fields as JSON","zerolog.New logger creates a context child logger via With()"],"goal":"verify github.com/rs/zerolog.New in pkg:golang/github.com/rs/zerolog@v1.15.0","kind":"HOW","packages":["pkg:golang/github.com/rs/zerolog@v1.15.0"],"schemaVersion":1,"symbols":["github.com/rs/zerolog.New"]},"contractCommand":["go","run","./test"],"environment":{"arch":"amd64","compiler":"go","compilerVersion":"1.26.6","distro":"ubuntu","ecosystem":"golang","language":"go","languageVersion":"1.26.6","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/rs/zerolog@v1.15.0"],"schemaVersion":1,"subject":"pkg:golang/github.com/rs/zerolog@v1.15.0","symbols":["github.com/rs/zerolog.New"],"verifierAdapter":"golang@1"}

module sample

go 1.26.6

require github.com/rs/zerolog v1.15.0

github.com/coreos/go-systemd v0.0.0-20190321100706-95778dfbb74e/go.mod h1:F5haX7vjVVG0kc13fIWeqUViNPyEJxv/OmvnBo0Yme4=
github.com/pkg/errors v0.8.1/go.mod h1:bwawxfHBFNV+L2hUp1rHADufV3IMtnDRdf1r5NINEl0=
github.com/rs/xid v1.2.1/go.mod h1:+uKXf+4Djp6Md1KODXJxgGQPKngRmWyn10oCKFzNHOQ=
github.com/rs/zerolog v1.15.0 h1:uPRuwkWF4J6fGsJ2R0Gn2jB1EQiav9k3S6CSdygQJXY=
github.com/rs/zerolog v1.15.0/go.mod h1:xYTKnLHcpfU2225ny5qZjxnj9NvkumZYjJHlAThCjNc=
github.com/zenazn/goji v0.9.0/go.mod h1:7S9M489iMyHBNxwZnk9/EHS098H4/F6TATF2mIxtB1Q=
golang.org/x/crypto v0.0.0-20190308221718-c2843e01d9a2/go.mod h1:djNgcEr1/C05ACkg1iLfiJU5Ep61QUkGW8qpdssI0+w=
golang.org/x/net v0.0.0-20190311183353-d8887717615a/go.mod h1:t9HGtf8HONx5eT2rtn7q6eTqICYqUVnKs3thJo3Qplg=
golang.org/x/sync v0.0.0-20190423024810-112230192c58/go.mod h1:RxMgew5VJxzue5/jJTE5uejpjVlOe/izrB70Jof72aM=
golang.org/x/sys v0.0.0-20190215142949-d0b11bdaac8a/go.mod h1:STP8DvDyc/dI5b8T5hshtkjS+E42TnysNCUPdjciGhY=
golang.org/x/text v0.3.0/go.mod h1:NqM8EUOU14njkJ3fqMW+pc6Ldnwhi/IjpwHt7yyuwOQ=
golang.org/x/tools v0.0.0-20190425163242-31fd60d6bfdc/go.mod h1:RgjU9mgBXZiqYHBnxXauZ1Gv1EHHAz9KjViQ78xBX0Q=

package main

import (
	"bytes"
	"fmt"

	"github.com/rs/zerolog"
)

func main() {
	buf := &bytes.Buffer{}
	logger := zerolog.New(buf)

	logger.Info().Str("app", "csx-sample").Msg("application started")
	fmt.Printf("Log output: %s\n", buf.String())
}

{
  "schemaVersion": 1,
  "goal": "verify github.com/rs/zerolog.New in pkg:golang/github.com/rs/zerolog@v1.15.0",
  "kind": "HOW",
  "packages": [
    "pkg:golang/github.com/rs/zerolog@v1.15.0"
  ],
  "symbols": [
    "github.com/rs/zerolog.New"
  ]
}

package main

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

	"github.com/rs/zerolog"
)

func main() {
	// Assertion 1: zerolog.New creates a Logger writing structured JSON to an io.Writer
	{
		buf := &bytes.Buffer{}
		logger := zerolog.New(buf)
		logger.Log().Msg("test message")

		var parsed map[string]interface{}
		if err := json.Unmarshal(buf.Bytes(), &parsed); err != nil {
			fmt.Fprintf(os.Stderr, "assertion 1 failed: invalid JSON output: %v\n", err)
			os.Exit(1)
		}
		if parsed["message"] != "test message" {
			fmt.Fprintf(os.Stderr, "assertion 1 failed: expected message %q, got %v\n", "test message", parsed["message"])
			os.Exit(1)
		}
	}

	// Assertion 2: zerolog.New writes log events formatted with message and level
	{
		buf := &bytes.Buffer{}
		logger := zerolog.New(buf)
		logger.Info().Msg("hello world")

		var parsed map[string]interface{}
		if err := json.Unmarshal(buf.Bytes(), &parsed); err != nil {
			fmt.Fprintf(os.Stderr, "assertion 2 failed: invalid JSON output: %v\n", err)
			os.Exit(1)
		}
		if parsed["level"] != "info" || parsed["message"] != "hello world" {
			fmt.Fprintf(os.Stderr, "assertion 2 failed: expected level 'info' and message 'hello world', got %+v\n", parsed)
			os.Exit(1)
		}
	}

	// Assertion 3: zerolog.New with nil writer creates a Logger that safely discards log output
	{
		logger := zerolog.New(nil)
		logger.Info().Str("field", "value").Msg("discarded message")
	}

	// Assertion 4: zerolog.New logger formats structured key-value fields as JSON
	{
		buf := &bytes.Buffer{}
		logger := zerolog.New(buf)
		logger.Info().Str("service", "auth").Int("port", 8080).Bool("enabled", true).Msg("server starting")

		var parsed map[string]interface{}
		if err := json.Unmarshal(buf.Bytes(), &parsed); err != nil {
			fmt.Fprintf(os.Stderr, "assertion 4 failed: invalid JSON output: %v\n", err)
			os.Exit(1)
		}
		if parsed["service"] != "auth" || parsed["port"] != float64(8080) || parsed["enabled"] != true || parsed["message"] != "server starting" {
			fmt.Fprintf(os.Stderr, "assertion 4 failed: field values mismatch: %+v\n", parsed)
			os.Exit(1)
		}
	}

	// Assertion 5: zerolog.New logger creates a context child logger via With()
	{
		buf := &bytes.Buffer{}
		logger := zerolog.New(buf)
		child := logger.With().Str("component", "worker").Int("worker_id", 1).Logger()
		child.Info().Msg("task executed")

		var parsed map[string]interface{}
		if err := json.Unmarshal(buf.Bytes(), &parsed); err != nil {
			fmt.Fprintf(os.Stderr, "assertion 5 failed: invalid JSON output: %v\n", err)
			os.Exit(1)
		}
		if parsed["component"] != "worker" || parsed["worker_id"] != float64(1) || parsed["message"] != "task executed" {
			fmt.Fprintf(os.Stderr, "assertion 5 failed: child logger context mismatch: %+v\n", parsed)
			os.Exit(1)
		}
	}

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