github.com/sirupsen/logrus v1.6.0: Entry, Hook, Logger.AddHook

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 pkg:golang/github.com/sirupsen/logrus@v1.6.0
Kind: HOW

Use EXACTLY these public packages and versions:
  - pkg:golang/github.com/sirupsen/logrus@v1.6.0
Demonstrate these symbols/APIs:
  - github.com/sirupsen/logrus.Entry
  - github.com/sirupsen/logrus.Hook
  - github.com/sirupsen/logrus.Logger.AddHook

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:d8f7601715def6c5d0b8d2b08b2ba78224d1a7bd0e02daaa5df4762285b2d86a","contract":["logrus.Hook interface captures log entries via Levels and Fire methods","logger.AddHook registers hook to fire on subscribed levels while ignoring unsubscribed levels","logrus.Entry passed to Hook.Fire retains message, level, timestamp and structured fields","logger.WithError chains error instances into entry fields captured by hooks"],"goal":"verify pkg:golang/github.com/sirupsen/logrus@v1.6.0","kind":"HOW","packages":["pkg:golang/github.com/sirupsen/logrus@v1.6.0"],"schemaVersion":1,"symbols":["github.com/sirupsen/logrus.Entry","github.com/sirupsen/logrus.Hook","github.com/sirupsen/logrus.Logger.AddHook"]},"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/github.com/sirupsen/logrus@v1.6.0"],"schemaVersion":1,"subject":"pkg:golang/github.com/sirupsen/logrus@v1.6.0","symbols":["github.com/sirupsen/logrus.Entry","github.com/sirupsen/logrus.Hook","github.com/sirupsen/logrus.Logger.AddHook"],"verifierAdapter":"golang@1"}

module sample

go 1.22

require github.com/sirupsen/logrus v1.6.0

require (
	github.com/konsorten/go-windows-terminal-sequences v1.0.3 // indirect
	golang.org/x/sys v0.0.0-20190422165155-953cdadca894 // 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/konsorten/go-windows-terminal-sequences v1.0.3 h1:CE8S1cTafDpPvMhIxNJKvHsGVBgn1xWYf1NbHQhywc8=
github.com/konsorten/go-windows-terminal-sequences v1.0.3/go.mod h1:T0+1ngSBFLxvqU3pZ+m/2kptfBszLMUkC4ZK/EgS/cQ=
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/sirupsen/logrus v1.6.0 h1:UBcNElsrwanuuMsnGSlYmtmgbb23qDR5dG+6X6Oo89I=
github.com/sirupsen/logrus v1.6.0/go.mod h1:7uNnSEd1DgxDLC74fIahvMZmmYsHGZGEOFrfsX/uA88=
github.com/stretchr/testify v1.2.2 h1:bSDNvY7ZPG5RlJ8otE/7V6gMiyenm9RtJ7IUVIAoJ1w=
github.com/stretchr/testify v1.2.2/go.mod h1:a8OnRcib4nhh0OaRAV+Yts87kKdq0PP7pXfy6kDkUVs=
golang.org/x/sys v0.0.0-20190422165155-953cdadca894 h1:Cz4ceDQGXuKRnVBDTS23GTn/pU5OE2C0WrNTOYK1Uuc=
golang.org/x/sys v0.0.0-20190422165155-953cdadca894/go.mod h1:h1NjWce9XRLGQEsW7wpKNCjG9DtNlClVuFLEZdDNbEs=

package sample

import (
	"io"
	"sync"

	"github.com/sirupsen/logrus"
)

// MemoryHook captures log entries in memory for specified log levels.
type MemoryHook struct {
	mu      sync.Mutex
	levels  []logrus.Level
	entries []*logrus.Entry
}

// NewMemoryHook returns a new MemoryHook for the given log levels.
func NewMemoryHook(levels ...logrus.Level) *MemoryHook {
	return &MemoryHook{
		levels:  levels,
		entries: make([]*logrus.Entry, 0),
	}
}

// Levels returns the logrus levels for which this hook should be fired.
func (h *MemoryHook) Levels() []logrus.Level {
	return h.levels
}

// Fire is invoked by logrus when a log entry matches one of the hook's levels.
func (h *MemoryHook) Fire(entry *logrus.Entry) error {
	h.mu.Lock()
	defer h.mu.Unlock()
	copied := *entry
	dataCopy := make(logrus.Fields, len(entry.Data))
	for k, v := range entry.Data {
		dataCopy[k] = v
	}
	copied.Data = dataCopy
	h.entries = append(h.entries, &copied)
	return nil
}

// Entries returns all recorded log entries.
func (h *MemoryHook) Entries() []*logrus.Entry {
	h.mu.Lock()
	defer h.mu.Unlock()
	res := make([]*logrus.Entry, len(h.entries))
	copy(res, h.entries)
	return res
}

// Count returns the number of captured log entries.
func (h *MemoryHook) Count() int {
	h.mu.Lock()
	defer h.mu.Unlock()
	return len(h.entries)
}

// SetupLogger initializes a Logger with discard output, minimum level, and attaches the hook.
func SetupLogger(out io.Writer, level logrus.Level, hook logrus.Hook) *logrus.Logger {
	l := logrus.New()
	l.SetOutput(out)
	l.SetLevel(level)
	if hook != nil {
		l.AddHook(hook)
	}
	return l
}

{
  "schemaVersion": 1,
  "goal": "verify pkg:golang/github.com/sirupsen/logrus@v1.6.0",
  "kind": "HOW",
  "packages": [
    "pkg:golang/github.com/sirupsen/logrus@v1.6.0"
  ],
  "symbols": [
    "github.com/sirupsen/logrus.Entry",
    "github.com/sirupsen/logrus.Hook",
    "github.com/sirupsen/logrus.Logger.AddHook"
  ]
}

package main

import (
	"errors"
	"fmt"
	"io"
	"os"

	"github.com/sirupsen/logrus"
	"sample"
)

func main() {
	// Assertion 1: logrus.Hook interface captures log entries via Levels and Fire methods
	hook := sample.NewMemoryHook(logrus.WarnLevel, logrus.ErrorLevel)
	var _ logrus.Hook = hook

	levels := hook.Levels()
	if len(levels) != 2 || levels[0] != logrus.WarnLevel || levels[1] != logrus.ErrorLevel {
		fmt.Fprintf(os.Stderr, "FAIL: expected hook levels [warn, error], got %v\n", levels)
		os.Exit(1)
	}

	// Assertion 2: logger.AddHook registers hook to fire on subscribed levels while ignoring unsubscribed levels
	logger := sample.SetupLogger(io.Discard, logrus.DebugLevel, hook)

	// InfoLevel is not subscribed to by hook
	logger.Info("informational event should be skipped by hook")
	if hook.Count() != 0 {
		fmt.Fprintf(os.Stderr, "FAIL: hook fired for unsubscribed InfoLevel, count = %d\n", hook.Count())
		os.Exit(1)
	}

	// WarnLevel is subscribed
	logger.WithField("component", "storage").Warn("disk space warning")
	if hook.Count() != 1 {
		fmt.Fprintf(os.Stderr, "FAIL: expected 1 hook entry after Warn, got %d\n", hook.Count())
		os.Exit(1)
	}

	// Assertion 3: logrus.Entry passed to Hook.Fire retains message, level, timestamp and structured fields
	entries := hook.Entries()
	entry := entries[0]
	if entry.Message != "disk space warning" {
		fmt.Fprintf(os.Stderr, "FAIL: expected message 'disk space warning', got %q\n", entry.Message)
		os.Exit(1)
	}
	if entry.Level != logrus.WarnLevel {
		fmt.Fprintf(os.Stderr, "FAIL: expected level WarnLevel, got %v\n", entry.Level)
		os.Exit(1)
	}
	if val, ok := entry.Data["component"]; !ok || val != "storage" {
		fmt.Fprintf(os.Stderr, "FAIL: expected field component='storage', got %v\n", entry.Data["component"])
		os.Exit(1)
	}
	if entry.Time.IsZero() {
		fmt.Fprintf(os.Stderr, "FAIL: expected valid non-zero timestamp on entry\n")
		os.Exit(1)
	}

	// Assertion 4: logger.WithError chains error instances into entry fields captured by hooks
	sampleErr := errors.New("connection reset by peer")
	logger.WithError(sampleErr).Error("database query failed")

	if hook.Count() != 2 {
		fmt.Fprintf(os.Stderr, "FAIL: expected 2 hook entries after Error, got %d\n", hook.Count())
		os.Exit(1)
	}

	errEntry := hook.Entries()[1]
	if errEntry.Level != logrus.ErrorLevel {
		fmt.Fprintf(os.Stderr, "FAIL: expected level ErrorLevel, got %v\n", errEntry.Level)
		os.Exit(1)
	}
	if errVal, ok := errEntry.Data[logrus.ErrorKey]; !ok || errVal != sampleErr {
		fmt.Fprintf(os.Stderr, "FAIL: expected error field %v, got %v\n", sampleErr, errEntry.Data[logrus.ErrorKey])
		os.Exit(1)
	}

	fmt.Println("PASS: all logrus hook contract assertions passed")
}