go.uber.org/zap v1.13.0: Logger

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 go.uber.org/zap.Logger in pkg:golang/go.uber.org/zap@v1.13.0
Kind: HOW

Use EXACTLY these public packages and versions:
  - pkg:golang/go.uber.org/zap@v1.13.0
Demonstrate these symbols/APIs:
  - go.uber.org/zap.Logger

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:sha256:75a9df303075bd4e4db6f1a535a03a4399fa8de62728c4240f5c79d6b6c349b3","contract":["zap.Logger.Named produces dot-delimited hierarchical logger names","zap.Logger.With attaches context fields immutably without altering parent logger","zap.Logger.Check returns a non-nil CheckedEntry for enabled levels and nil for disabled levels","zap.Logger.Sugar converts to SugaredLogger and Desugar recovers the underlying zap.Logger"],"goal":"verify go.uber.org/zap.Logger in pkg:golang/go.uber.org/zap@v1.13.0","kind":"HOW","packages":["pkg:golang/go.uber.org/zap@v1.13.0"],"schemaVersion":1,"symbols":["go.uber.org/zap.Logger"]},"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/go.uber.org/zap@v1.13.0"],"schemaVersion":1,"subject":"pkg:golang/go.uber.org/zap@v1.13.0","symbols":["go.uber.org/zap.Logger"],"verifierAdapter":"golang@1"}

module sample

go 1.26.6

require go.uber.org/zap v1.13.0

require (
	github.com/BurntSushi/toml v0.3.1 // indirect
	go.uber.org/atomic v1.5.0 // indirect
	go.uber.org/multierr v1.3.0 // indirect
	go.uber.org/tools v0.0.0-20190618225709-2cfd321de3ee // indirect
	golang.org/x/lint v0.0.0-20190930215403-16217165b5de // indirect
	golang.org/x/tools v0.0.0-20191029190741-b9c20aec41a5 // indirect
	honnef.co/go/tools v0.0.1-2019.2.3 // indirect
)

github.com/BurntSushi/toml v0.3.1 h1:WXkYYl6Yr3qBf1K79EBnL4mak0OimBfB0XUf9Vl28OQ=
github.com/BurntSushi/toml v0.3.1/go.mod h1:xHWCNGjB5oqiDr8zfno3MHue2Ht5sIBksp03qcyfWMU=
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/google/renameio v0.1.0/go.mod h1:KWCgfxg9yswjAJkECMjeO8J8rahYeXnNhOm40UhjYkI=
github.com/kisielk/gotool v1.0.0/go.mod h1:XhKaO+MFFWcvkIS/tQcRk01m1F5IRFswLeQ+oQHNcck=
github.com/kr/pretty v0.1.0/go.mod h1:dAy3ld7l9f0ibDNOQOHHMYYIIbhfbHSm3C4ZsoJORNo=
github.com/kr/pty v1.1.1/go.mod h1:pFQYn66WHrOpPYNljwOMqo10TkYh1fy3cYio2l3bCsQ=
github.com/kr/text v0.1.0/go.mod h1:4Jbv+DJW3UT/LiOwJeYQe1efqtUx/iVham/4vfdArNI=
github.com/pkg/errors v0.8.1 h1:iURUrRGxPUNPdy5/HRSm+Yj6okJ6UtLINN0Q9M4+h3I=
github.com/pkg/errors v0.8.1/go.mod h1:bwawxfHBFNV+L2hUp1rHADufV3IMtnDRdf1r5NINEl0=
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/rogpeppe/go-internal v1.3.0/go.mod h1:M8bDsm7K2OlrFYOpmOWEs/qY81heoFRclV5y23lUDJ4=
github.com/stretchr/objx v0.1.0/go.mod h1:HFkY916IF+rwdDfMAkV7OtwuqBVzrE8GR6GFx+wExME=
github.com/stretchr/testify v1.3.0/go.mod h1:M5WIy9Dh21IEIfnGCwXGc5bZfKNJtfHm1UVUgZn+9EI=
github.com/stretchr/testify v1.4.0 h1:2E4SXV/wtOkTonXsotYi4li6zVWxYlZuYNCXe9XRJyk=
github.com/stretchr/testify v1.4.0/go.mod h1:j7eGeouHqKxXV5pUuKE4zz7dFj8WfuZ+81PSLYec5m4=
go.uber.org/atomic v1.5.0 h1:OI5t8sDa1Or+q8AeE+yKeB/SDYioSHAgcVljj9JIETY=
go.uber.org/atomic v1.5.0/go.mod h1:sABNBOSYdrvTF6hTgEIbc7YasKWGhgEQZyfxyTvoXHQ=
go.uber.org/multierr v1.3.0 h1:sFPn2GLc3poCkfrpIXGhBD2X0CMIo4Q/zSULXrj/+uc=
go.uber.org/multierr v1.3.0/go.mod h1:VgVr7evmIr6uPjLBxg28wmKNXyqE9akIJ5XnfpiKl+4=
go.uber.org/tools v0.0.0-20190618225709-2cfd321de3ee h1:0mgffUl7nfd+FpvXMVz4IDEaUSmT1ysygQC7qYo7sG4=
go.uber.org/tools v0.0.0-20190618225709-2cfd321de3ee/go.mod h1:vJERXedbb3MVM5f9Ejo0C68/HhF8uaILCdgjnY+goOA=
go.uber.org/zap v1.13.0 h1:nR6NoDBgAf67s68NhaXbsojM+2gxp3S1hWkHDl27pVU=
go.uber.org/zap v1.13.0/go.mod h1:zwrFLgMcdUuIBviXEYEH1YKNaOBnKXsx2IPda5bBwHM=
golang.org/x/crypto v0.0.0-20190308221718-c2843e01d9a2/go.mod h1:djNgcEr1/C05ACkg1iLfiJU5Ep61QUkGW8qpdssI0+w=
golang.org/x/crypto v0.0.0-20190510104115-cbcb75029529/go.mod h1:yigFU9vqHzYiE8UmvKecakEJjdnWj3jj499lnFckfCI=
golang.org/x/lint v0.0.0-20190930215403-16217165b5de h1:5hukYrvBGR8/eNkX5mdUezrA6JiaEZDtJb9Ei+1LlBs=
golang.org/x/lint v0.0.0-20190930215403-16217165b5de/go.mod h1:6SW0HCj/g11FgYtHlgUYUwCkIfeOF89ocIRzGO/8vkc=
golang.org/x/mod v0.0.0-20190513183733-4bf6d317e70e/go.mod h1:mXi4GBBbnImb6dmsKGUJ2LatrhH/nqhxcFungHvyanc=
golang.org/x/net v0.0.0-20190311183353-d8887717615a/go.mod h1:t9HGtf8HONx5eT2rtn7q6eTqICYqUVnKs3thJo3Qplg=
golang.org/x/net v0.0.0-20190404232315-eb5bcb51f2a3/go.mod h1:t9HGtf8HONx5eT2rtn7q6eTqICYqUVnKs3thJo3Qplg=
golang.org/x/net v0.0.0-20190620200207-3b0461eec859/go.mod h1:z5CRVTTTmAJ677TzLLGU+0bjPO0LkuOLi4/5GtJWs/s=
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/sys v0.0.0-20190412213103-97732733099d/go.mod h1:h1NjWce9XRLGQEsW7wpKNCjG9DtNlClVuFLEZdDNbEs=
golang.org/x/text v0.3.0/go.mod h1:NqM8EUOU14njkJ3fqMW+pc6Ldnwhi/IjpwHt7yyuwOQ=
golang.org/x/tools v0.0.0-20190311212946-11955173bddd/go.mod h1:LCzVGOaR6xXOjkQ3onu1FJEFr0SW1gC7cKk1uF8kGRs=
golang.org/x/tools v0.0.0-20190621195816-6e04913cbbac/go.mod h1:/rFqwRUd4F7ZHNgwSSTFct+R/Kf4OFW1sUzUTQQTgfc=
golang.org/x/tools v0.0.0-20191029041327-9cc4af7d6b2c/go.mod h1:b+2E5dAYhXwXZwtnZ6UAqBI28+e2cm9otk0dWdXHAEo=
golang.org/x/tools v0.0.0-20191029190741-b9c20aec41a5 h1:hKsoRgsbwY1NafxrwTs+k64bikrLBkAgPir1TNCj3Zs=
golang.org/x/tools v0.0.0-20191029190741-b9c20aec41a5/go.mod h1:b+2E5dAYhXwXZwtnZ6UAqBI28+e2cm9otk0dWdXHAEo=
golang.org/x/xerrors v0.0.0-20190717185122-a985d3407aa7/go.mod h1:I/5z698sn9Ka8TeJc9MKroUUfqBBauWjQqLJ2OPfmY0=
gopkg.in/check.v1 v0.0.0-20161208181325-20d25e280405/go.mod h1:Co6ibVJAznAaIkqp8huTwlJQCZ016jof/cbN4VW5Yz0=
gopkg.in/check.v1 v1.0.0-20180628173108-788fd7840127/go.mod h1:Co6ibVJAznAaIkqp8huTwlJQCZ016jof/cbN4VW5Yz0=
gopkg.in/errgo.v2 v2.1.0/go.mod h1:hNsd1EY+bozCKY1Ytp96fpM3vjJbqLJn88ws8XvfDNI=
gopkg.in/yaml.v2 v2.2.2 h1:ZCJp+EgiOT7lHqUV2J862kp8Qj64Jo6az82+3Td9dZw=
gopkg.in/yaml.v2 v2.2.2/go.mod h1:hI93XBmqTisBFMUTm0b8Fm+jr3Dg1NNxqwp+5A1VGuI=
honnef.co/go/tools v0.0.1-2019.2.3 h1:3JgtbtFHMiCmsznwGVTUWbgGov+pVqnlf1dEJTNAXeM=
honnef.co/go/tools v0.0.1-2019.2.3/go.mod h1:a3bituU0lyd329TUQxRnasdCoJDkEUEAqEt0JzvZhAg=

package sample

import (
	"go.uber.org/zap"
	"go.uber.org/zap/zapcore"
	"go.uber.org/zap/zaptest/observer"
)

// NewObservedLogger creates a zap.Logger backed by an in-memory observer core.
func NewObservedLogger(level zapcore.Level) (*zap.Logger, *observer.ObservedLogs) {
	core, logs := observer.New(level)
	return zap.New(core), logs
}

// NamedChild creates a child logger with a hierarchical name.
func NamedChild(logger *zap.Logger, name string) *zap.Logger {
	return logger.Named(name)
}

// WithFields returns a new child logger with structured context fields attached.
func WithFields(logger *zap.Logger, fields ...zap.Field) *zap.Logger {
	return logger.With(fields...)
}

// IsEnabled checks whether logging is enabled for the specified level.
func IsEnabled(logger *zap.Logger, level zapcore.Level) bool {
	return logger.Check(level, "check") != nil
}

// SugarRoundTrip converts a zap.Logger to SugaredLogger and recovers the base logger.
func SugarRoundTrip(logger *zap.Logger) *zap.Logger {
	return logger.Sugar().Desugar()
}

{
  "schemaVersion": 1,
  "goal": "verify go.uber.org/zap.Logger in pkg:golang/go.uber.org/zap@v1.13.0",
  "kind": "HOW",
  "packages": [
    "pkg:golang/go.uber.org/zap@v1.13.0"
  ],
  "symbols": [
    "go.uber.org/zap.Logger"
  ]
}

package main

import (
	"fmt"
	"os"

	"go.uber.org/zap"
	"go.uber.org/zap/zapcore"
	"sample"
)

func main() {
	// Assertion 1: zap.Logger.Named produces dot-delimited hierarchical logger names
	baseLogger, logs := sample.NewObservedLogger(zapcore.DebugLevel)
	parent := sample.NamedChild(baseLogger, "parent")
	child := sample.NamedChild(parent, "child")
	child.Info("hierarchical message")

	entries := logs.All()
	if len(entries) != 1 {
		fmt.Fprintf(os.Stderr, "expected 1 log entry, got %d\n", len(entries))
		os.Exit(1)
	}
	if entries[0].LoggerName != "parent.child" {
		fmt.Fprintf(os.Stderr, "expected logger name 'parent.child', got %q\n", entries[0].LoggerName)
		os.Exit(1)
	}

	// Assertion 2: zap.Logger.With attaches context fields immutably without altering parent logger
	baseWithLogger, logs2 := sample.NewObservedLogger(zapcore.DebugLevel)
	childWithLogger := sample.WithFields(baseWithLogger, zap.String("service", "payment"))

	baseWithLogger.Info("base entry")
	childWithLogger.Info("child entry")

	allLogs2 := logs2.All()
	if len(allLogs2) != 2 {
		fmt.Fprintf(os.Stderr, "expected 2 log entries, got %d\n", len(allLogs2))
		os.Exit(1)
	}
	baseCtx := allLogs2[0].ContextMap()
	if _, exists := baseCtx["service"]; exists {
		fmt.Fprintf(os.Stderr, "parent logger unexpectedly contained child field: %#v\n", baseCtx)
		os.Exit(1)
	}
	childCtx := allLogs2[1].ContextMap()
	if val, exists := childCtx["service"]; !exists || val != "payment" {
		fmt.Fprintf(os.Stderr, "child logger missing expected field: %#v\n", childCtx)
		os.Exit(1)
	}

	// Assertion 3: zap.Logger.Check returns a non-nil CheckedEntry for enabled levels and nil for disabled levels
	infoLogger, _ := sample.NewObservedLogger(zapcore.InfoLevel)
	if sample.IsEnabled(infoLogger, zapcore.DebugLevel) {
		fmt.Fprintf(os.Stderr, "expected DebugLevel to be disabled for InfoLevel logger\n")
		os.Exit(1)
	}
	if !sample.IsEnabled(infoLogger, zapcore.InfoLevel) {
		fmt.Fprintf(os.Stderr, "expected InfoLevel to be enabled for InfoLevel logger\n")
		os.Exit(1)
	}
	if !sample.IsEnabled(infoLogger, zapcore.ErrorLevel) {
		fmt.Fprintf(os.Stderr, "expected ErrorLevel to be enabled for InfoLevel logger\n")
		os.Exit(1)
	}

	// Assertion 4: zap.Logger.Sugar converts to SugaredLogger and Desugar recovers the underlying zap.Logger
	desugared := sample.SugarRoundTrip(baseLogger)
	if desugared == nil {
		fmt.Fprintf(os.Stderr, "expected non-nil logger after sugar-desugar roundtrip\n")
		os.Exit(1)
	}
	desugared.Info("recovered logger entry")
	recoveredEntries := logs.FilterMessage("recovered logger entry").All()
	if len(recoveredEntries) != 1 {
		fmt.Fprintf(os.Stderr, "expected 1 entry from recovered logger, got %d\n", len(recoveredEntries))
		os.Exit(1)
	}

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