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

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.AtomicLevel 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.AtomicLevel

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:sha256:507c0977b11759da20db0cf3e3e90d4112733274b39d9e044abd253fe6375c3a","contract":["CreateDynamicLevelLogger creates a zap.Logger configured with an AtomicLevel threshold and buffer output","SetLevel dynamically updates the active log level threshold at runtime","LogMessages emits log entries filtered according to the current AtomicLevel threshold"],"goal":"verify go.uber.org/zap.AtomicLevel 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.AtomicLevel"]},"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/go.uber.org/zap@v1.13.0"],"schemaVersion":1,"subject":"pkg:golang/go.uber.org/zap@v1.13.0","symbols":["go.uber.org/zap.AtomicLevel"],"verifierAdapter":"golang@1"}

module example.com/sample

go 1.22.0

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 (
	"bytes"

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

// DynamicLogger encapsulates a zap.Logger and its AtomicLevel controller.
type DynamicLogger struct {
	Logger *zap.Logger
	Level  zap.AtomicLevel
}

// CreateDynamicLevelLogger initializes a zap.Logger with a dynamically adjustable AtomicLevel.
func CreateDynamicLevelLogger(buf *bytes.Buffer, initialLevel zapcore.Level) *DynamicLogger {
	atom := zap.NewAtomicLevelAt(initialLevel)
	encoderCfg := zapcore.EncoderConfig{
		MessageKey:     "msg",
		LevelKey:       "level",
		NameKey:        "logger",
		EncodeLevel:    zapcore.LowercaseLevelEncoder,
		EncodeTime:     zapcore.ISO8601TimeEncoder,
		EncodeDuration: zapcore.StringDurationEncoder,
	}
	core := zapcore.NewCore(
		zapcore.NewJSONEncoder(encoderCfg),
		zapcore.AddSync(buf),
		atom,
	)
	logger := zap.New(core)
	return &DynamicLogger{
		Logger: logger,
		Level:  atom,
	}
}

// SetLevel dynamically modifies the minimum logging level threshold at runtime.
func (d *DynamicLogger) SetLevel(level zapcore.Level) {
	d.Level.SetLevel(level)
}

// GetLevel returns the current logging level threshold.
func (d *DynamicLogger) GetLevel() zapcore.Level {
	return d.Level.Level()
}

// LogMessages logs debug, info, and warn messages to demonstrate level filtering.
func (d *DynamicLogger) LogMessages(debugMsg, infoMsg, warnMsg string) {
	if d.Logger != nil {
		d.Logger.Debug(debugMsg)
		d.Logger.Info(infoMsg)
		d.Logger.Warn(warnMsg)
	}
}

{
  "schemaVersion": 1,
  "goal": "verify go.uber.org/zap.AtomicLevel 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.AtomicLevel"
  ]
}

package main

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

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

type logEntry struct {
	Level string `json:"level"`
	Msg   string `json:"msg"`
}

func parseEntries(buf *bytes.Buffer) ([]logEntry, error) {
	var entries []logEntry
	decoder := json.NewDecoder(buf)
	for decoder.More() {
		var entry logEntry
		if err := decoder.Decode(&entry); err != nil {
			return nil, err
		}
		entries = append(entries, entry)
	}
	return entries, nil
}

func main() {
	var buf bytes.Buffer

	// 1. Initialized at InfoLevel: Debug messages should be omitted, Info and Warn should be present
	dynLogger := sample.CreateDynamicLevelLogger(&buf, zapcore.InfoLevel)
	if dynLogger == nil || dynLogger.Logger == nil {
		fmt.Fprintf(os.Stderr, "expected non-nil dynamic logger\n")
		os.Exit(1)
	}

	if dynLogger.GetLevel() != zapcore.InfoLevel {
		fmt.Fprintf(os.Stderr, "expected initial level InfoLevel, got %v\n", dynLogger.GetLevel())
		os.Exit(1)
	}

	dynLogger.LogMessages("debug message 1", "info message 1", "warn message 1")

	entries, err := parseEntries(&buf)
	if err != nil {
		fmt.Fprintf(os.Stderr, "failed to decode log entries: %v\n", err)
		os.Exit(1)
	}

	if len(entries) != 2 {
		fmt.Fprintf(os.Stderr, "expected 2 entries at InfoLevel, got %d\n", len(entries))
		os.Exit(1)
	}
	if entries[0].Level != "info" || entries[0].Msg != "info message 1" {
		fmt.Fprintf(os.Stderr, "unexpected entry 0: %+v\n", entries[0])
		os.Exit(1)
	}
	if entries[1].Level != "warn" || entries[1].Msg != "warn message 1" {
		fmt.Fprintf(os.Stderr, "unexpected entry 1: %+v\n", entries[1])
		os.Exit(1)
	}

	// 2. Change level dynamically to DebugLevel: Debug, Info, and Warn messages should all be captured
	buf.Reset()
	dynLogger.SetLevel(zapcore.DebugLevel)
	if dynLogger.GetLevel() != zapcore.DebugLevel {
		fmt.Fprintf(os.Stderr, "expected dynamic level DebugLevel, got %v\n", dynLogger.GetLevel())
		os.Exit(1)
	}

	dynLogger.LogMessages("debug message 2", "info message 2", "warn message 2")

	entries, err = parseEntries(&buf)
	if err != nil {
		fmt.Fprintf(os.Stderr, "failed to decode log entries: %v\n", err)
		os.Exit(1)
	}

	if len(entries) != 3 {
		fmt.Fprintf(os.Stderr, "expected 3 entries at DebugLevel, got %d\n", len(entries))
		os.Exit(1)
	}
	if entries[0].Level != "debug" || entries[0].Msg != "debug message 2" {
		fmt.Fprintf(os.Stderr, "unexpected entry 0: %+v\n", entries[0])
		os.Exit(1)
	}
	if entries[1].Level != "info" || entries[1].Msg != "info message 2" {
		fmt.Fprintf(os.Stderr, "unexpected entry 1: %+v\n", entries[1])
		os.Exit(1)
	}
	if entries[2].Level != "warn" || entries[2].Msg != "warn message 2" {
		fmt.Fprintf(os.Stderr, "unexpected entry 2: %+v\n", entries[2])
		os.Exit(1)
	}

	// 3. Change level dynamically to WarnLevel: only Warn should be captured
	buf.Reset()
	dynLogger.SetLevel(zapcore.WarnLevel)
	if dynLogger.GetLevel() != zapcore.WarnLevel {
		fmt.Fprintf(os.Stderr, "expected dynamic level WarnLevel, got %v\n", dynLogger.GetLevel())
		os.Exit(1)
	}

	dynLogger.LogMessages("debug message 3", "info message 3", "warn message 3")

	entries, err = parseEntries(&buf)
	if err != nil {
		fmt.Fprintf(os.Stderr, "failed to decode log entries: %v\n", err)
		os.Exit(1)
	}

	if len(entries) != 1 {
		fmt.Fprintf(os.Stderr, "expected 1 entry at WarnLevel, got %d\n", len(entries))
		os.Exit(1)
	}
	if entries[0].Level != "warn" || entries[0].Msg != "warn message 3" {
		fmt.Fprintf(os.Stderr, "unexpected entry 0: %+v\n", entries[0])
		os.Exit(1)
	}

	fmt.Println("All contracts passed successfully.")
}