go.uber.org/zap v1.28.0: zapcore.InfoLevel

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/zapcore.InfoLevel 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/zapcore.InfoLevel

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:f1d099bfadb808ca1276a9b700bc11a4cadeee2301f0d8a0cbdad210cb2a504a","contract":["zapcore.InfoLevel defines the default informational logging threshold with string representation info and capital representation INFO","zapcore.NewCore configured at zapcore.InfoLevel enables InfoLevel and higher while filtering out DebugLevel entries","zap.Logger constructed with zapcore.InfoLevel core suppresses Debug logs and writes Info and Warn entries to the sink"],"goal":"verify go.uber.org/zap/zapcore.InfoLevel 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/zapcore.InfoLevel"]},"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@v1.28.0"],"schemaVersion":1,"subject":"pkg:golang/go.uber.org/zap@v1.28.0","symbols":["go.uber.org/zap/zapcore.InfoLevel"],"verifierAdapter":"golang@1"}

module example.com/sample

go 1.24.0

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 (
	"bytes"

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

// LogFilterWrapper encapsulates a zap.Logger configured at zapcore.InfoLevel and its output buffer.
type LogFilterWrapper struct {
	Logger *zap.Logger
	Buffer *bytes.Buffer
}

// NewInfoLogger constructs a zap.Logger with a core explicitly set to zapcore.InfoLevel.
func NewInfoLogger() *LogFilterWrapper {
	buf := &bytes.Buffer{}
	encCfg := zapcore.EncoderConfig{
		MessageKey:  "msg",
		LevelKey:    "level",
		EncodeLevel: zapcore.LowercaseLevelEncoder,
	}
	core := zapcore.NewCore(
		zapcore.NewJSONEncoder(encCfg),
		zapcore.AddSync(buf),
		zapcore.InfoLevel,
	)
	return &LogFilterWrapper{
		Logger: zap.New(core),
		Buffer: buf,
	}
}

// IsInfoEnabled returns whether InfoLevel is enabled on the underlying core.
func (w *LogFilterWrapper) IsInfoEnabled() bool {
	return w.Logger.Core().Enabled(zapcore.InfoLevel)
}

// IsDebugEnabled returns whether DebugLevel is enabled on the underlying core.
func (w *LogFilterWrapper) IsDebugEnabled() bool {
	return w.Logger.Core().Enabled(zapcore.DebugLevel)
}

// LogSampleEvents emits debug, info, and warn messages to demonstrate level filtering.
func (w *LogFilterWrapper) LogSampleEvents(debugMsg, infoMsg, warnMsg string) {
	w.Logger.Debug(debugMsg)
	w.Logger.Info(infoMsg)
	w.Logger.Warn(warnMsg)
}

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

package main

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

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

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

func main() {
	// 1. Verify zapcore.InfoLevel properties and string representations
	if zapcore.InfoLevel.String() != "info" {
		fmt.Fprintf(os.Stderr, "expected zapcore.InfoLevel string 'info', got %q\n", zapcore.InfoLevel.String())
		os.Exit(1)
	}
	if zapcore.InfoLevel.CapitalString() != "INFO" {
		fmt.Fprintf(os.Stderr, "expected zapcore.InfoLevel capital string 'INFO', got %q\n", zapcore.InfoLevel.CapitalString())
		os.Exit(1)
	}
	if zapcore.InfoLevel <= zapcore.DebugLevel {
		fmt.Fprintf(os.Stderr, "expected InfoLevel > DebugLevel\n")
		os.Exit(1)
	}
	if zapcore.InfoLevel >= zapcore.WarnLevel {
		fmt.Fprintf(os.Stderr, "expected InfoLevel < WarnLevel\n")
		os.Exit(1)
	}

	// 2. Verify zapcore.NewCore level enabling logic
	wrapper := sample.NewInfoLogger()
	if !wrapper.IsInfoEnabled() {
		fmt.Fprintf(os.Stderr, "expected InfoLevel to be enabled on logger core\n")
		os.Exit(1)
	}
	if wrapper.IsDebugEnabled() {
		fmt.Fprintf(os.Stderr, "expected DebugLevel to be disabled on InfoLevel logger core\n")
		os.Exit(1)
	}

	// 3. Verify logging filtering: Debug dropped, Info and Warn emitted
	wrapper.LogSampleEvents("debug message suppressed", "info message recorded", "warn message recorded")

	var entries []logEntry
	decoder := json.NewDecoder(wrapper.Buffer)
	for decoder.More() {
		var entry logEntry
		if err := decoder.Decode(&entry); err != nil {
			fmt.Fprintf(os.Stderr, "failed to decode json log entry: %v\n", err)
			os.Exit(1)
		}
		entries = append(entries, entry)
	}

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

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