go.uber.org/zap v1.28.0: 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@v1.28.0
Kind: HOW

Use EXACTLY these public packages and versions:
  - pkg:golang/go.uber.org/zap@v1.28.0
Demonstrate these symbols/APIs:
  - go.uber.org/zap.Logger
Required runtime conditions:
  - ecosystem: golang
  - language: go
  - packageManager: go@1.26.6
  - runtime: go@1.26.6

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:a0bdae335e3ab76d46fae875db8f19fa40ee8341511de7e45b41a3894fe1fcd9","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@v1.28.0","kind":"HOW","packages":["pkg:golang/go.uber.org/zap@v1.28.0"],"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@v1.28.0"],"schemaVersion":1,"subject":"pkg:golang/go.uber.org/zap@v1.28.0","symbols":["go.uber.org/zap.Logger"],"verifierAdapter":"golang@1"}

module sample

go 1.26.6

require go.uber.org/zap v1.28.0

require go.uber.org/multierr v1.10.0 // indirect

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/testify v1.8.1 h1:w7B6lhMri9wdJUVmEZPGGhZzrYTPvgJArz7wNPgYKsk=
github.com/stretchr/testify v1.8.1/go.mod h1:w2LPCIKwWwSfY2zedu0+kehJoqGctiVI29o6fzry7u4=
go.uber.org/goleak v1.3.0 h1:2K3zAYmnTNqV73imy9J1T3WC+gmCePx2hEGkimedGto=
go.uber.org/goleak v1.3.0/go.mod h1:CoHD4mav9JJNrW/WLlf7HGZPjdw8EucARQHekz1X6bE=
go.uber.org/multierr v1.10.0 h1:S0h4aNzvfcFsC3dRF1jLoaov7oRaKqRGC/pUEJ2yvPQ=
go.uber.org/multierr v1.10.0/go.mod h1:20+QtiLqy0Nd6FdQB9TLXag12DsQkrbs3htMFfDN80Y=
go.uber.org/zap v1.28.0 h1:IZzaP1Fv73/T/pBMLk4VutPl36uNC+OSUh3JLG3FIjo=
go.uber.org/zap v1.28.0/go.mod h1:rDLpOi171uODNm/mxFcuYWxDsqWSAVkFdX4XojSKg/Q=
go.yaml.in/yaml/v3 v3.0.4 h1:tfq32ie2Jv2UxXFdLJdh3jXuOzWiL1fo0bu/FbuKpbc=
go.yaml.in/yaml/v3 v3.0.4/go.mod h1:DhzuOOF2ATzADvBadXxruRBLzYTpT36CKvDb3+aBEFg=
gopkg.in/yaml.v3 v3.0.1 h1:fxVm/GzAzEWqLHuvctI91KS9hhNmmWOoWu0XTYJS7CA=
gopkg.in/yaml.v3 v3.0.1/go.mod h1:K4uyk7z7BCEPqu6E+C64Yfv1cQ7kz7rIZviUmN+EgEM=

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@v1.28.0",
  "kind": "HOW",
  "packages": [
    "pkg:golang/go.uber.org/zap@v1.28.0"
  ],
  "symbols": [
    "go.uber.org/zap.Logger"
  ],
  "runtimeConditions": {
    "ecosystem": "golang",
    "language": "go",
    "packageManager": "go@1.26.6",
    "runtime": "go@1.26.6"
  }
}

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.")
}