github.com/sirupsen/logrus v1.10.2: FieldKeyLogrusError

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 github.com/sirupsen/logrus.FieldKeyLogrusError in pkg:golang/github.com/sirupsen/logrus@v1.10.2
Kind: HOW

Use EXACTLY these public packages and versions:
  - pkg:golang/github.com/sirupsen/logrus@v1.10.2
Demonstrate these symbols/APIs:
  - github.com/sirupsen/logrus.FieldKeyLogrusError

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:sha256:1e84da70186490144640907a33ce27bc0a80424d9a57c6461d4d47c4a7596068","contract":["logrus.FieldKeyLogrusError constant equals \"logrus_error\"","logrus JSONFormatter includes FieldKeyLogrusError when field value cannot be added","logrus JSONFormatter does not include FieldKeyLogrusError when fields are valid","logrus JSONFormatter respects FieldKeyLogrusError override in FieldMap","logrus prefixFieldClashes prefixes user-provided FieldKeyLogrusError with fields."],"goal":"verify github.com/sirupsen/logrus.FieldKeyLogrusError in pkg:golang/github.com/sirupsen/logrus@v1.10.2","kind":"HOW","packages":["pkg:golang/github.com/sirupsen/logrus@v1.10.2"],"schemaVersion":1,"symbols":["github.com/sirupsen/logrus.FieldKeyLogrusError"]},"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@v1.10.2"],"schemaVersion":1,"subject":"pkg:golang/github.com/sirupsen/logrus@v1.10.2","symbols":["github.com/sirupsen/logrus.FieldKeyLogrusError"],"verifierAdapter":"golang@1"}

module example.com/sample

go 1.26.6

require github.com/sirupsen/logrus v1.10.2

require golang.org/x/sys v0.13.0 // indirect

github.com/sirupsen/logrus v1.10.2 h1:G2SED73/qrAu6YwbdxOD6peLkCBI3z7L+ykJFTXJBBo=
github.com/sirupsen/logrus v1.10.2/go.mod h1:SLEg8TqYulVKKfIGHldVp2K2aYz2DKSVBq4g/H5bR7Q=
github.com/stretchr/testify v1.12.1 h1:EuwCh5fleGS7H32xRwO3wRGT7DxrDhLAT6FF8MpWDWE=
github.com/stretchr/testify v1.12.1/go.mod h1:MDEgiDPPsNp5cuIrHPPCyornHKgEVbtFUmoNlxoYthg=
go.yaml.in/yaml/v3 v3.0.5 h1:N6y/pJk8buWs9NY5ERU2HSMfm+IuD/OtfdAnq6kESPw=
go.yaml.in/yaml/v3 v3.0.5/go.mod h1:HVTZu1O7/Vkt2N+BFy8Zza+lnLsABggaTM2ZpNIGuKg=
golang.org/x/sys v0.13.0 h1:Af8nKPmuFypiUBjVoU9V20FiaFXOcuZI21p0ycVYYGE=
golang.org/x/sys v0.13.0/go.mod h1:oPkhp1MJrh7nUepCBck5+mAzfO9JrbApNNgaTdGDITg=

package main

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

	"github.com/sirupsen/logrus"
)

func main() {
	buf := &bytes.Buffer{}
	logger := logrus.New()
	logger.SetOutput(buf)
	logger.SetFormatter(&logrus.JSONFormatter{})

	// Passing a non-serializable field value (e.g. a function) causes logrus
	// to record an entry error under FieldKeyLogrusError ("logrus_error").
	logger.WithField("invalid_fn", func() {}).Info("logging with invalid field")

	var output map[string]interface{}
	if err := json.Unmarshal(buf.Bytes(), &output); err != nil {
		log.Fatalf("failed to parse JSON log: %v", err)
	}

	errVal, hasErr := output[logrus.FieldKeyLogrusError]
	if !hasErr {
		log.Fatalf("expected key %q in log output", logrus.FieldKeyLogrusError)
	}

	fmt.Printf("Default %s key found: %v\n", logrus.FieldKeyLogrusError, errVal)

	// Customizing the key name using FieldMap
	buf.Reset()
	customLogger := logrus.New()
	customLogger.SetOutput(buf)
	customLogger.SetFormatter(&logrus.JSONFormatter{
		FieldMap: logrus.FieldMap{
			logrus.FieldKeyLogrusError: "custom_err_key",
		},
	})

	customLogger.WithField("invalid_fn", func() {}).Info("logging with custom field map")

	var customOutput map[string]interface{}
	if err := json.Unmarshal(buf.Bytes(), &customOutput); err != nil {
		log.Fatalf("failed to parse JSON log: %v", err)
	}

	if customErr, ok := customOutput["custom_err_key"]; ok {
		fmt.Printf("Custom error key found: %v\n", customErr)
	} else {
		log.Fatalf("expected custom error key in log output")
	}
}

{
  "schemaVersion": 1,
  "goal": "verify github.com/sirupsen/logrus.FieldKeyLogrusError in pkg:golang/github.com/sirupsen/logrus@v1.10.2",
  "kind": "HOW",
  "packages": [
    "pkg:golang/github.com/sirupsen/logrus@v1.10.2"
  ],
  "symbols": [
    "github.com/sirupsen/logrus.FieldKeyLogrusError"
  ]
}

package main

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

	"github.com/sirupsen/logrus"
)

func main() {
	// 1. logrus.FieldKeyLogrusError constant equals "logrus_error"
	if logrus.FieldKeyLogrusError != "logrus_error" {
		fmt.Fprintf(os.Stderr, "assertion 1 failed: expected FieldKeyLogrusError == \"logrus_error\", got %q\n", logrus.FieldKeyLogrusError)
		os.Exit(1)
	}

	// 2. logrus JSONFormatter includes FieldKeyLogrusError when field value cannot be added
	buf := &bytes.Buffer{}
	logger := logrus.New()
	logger.SetOutput(buf)
	logger.SetFormatter(&logrus.JSONFormatter{})

	logger.WithField("unsupported_field", func() {}).Info("test error field")

	var data map[string]interface{}
	if err := json.Unmarshal(buf.Bytes(), &data); err != nil {
		fmt.Fprintf(os.Stderr, "assertion 2 failed to unmarshal json: %v\n", err)
		os.Exit(1)
	}
	val, ok := data[logrus.FieldKeyLogrusError]
	if !ok {
		fmt.Fprintf(os.Stderr, "assertion 2 failed: %q not found in output\n", logrus.FieldKeyLogrusError)
		os.Exit(1)
	}
	valStr, ok := val.(string)
	if !ok || !strings.Contains(valStr, `skipping unsupported field "unsupported_field"`) {
		fmt.Fprintf(os.Stderr, "assertion 2 failed: expected error description, got %v\n", val)
		os.Exit(1)
	}

	// 3. logrus JSONFormatter does not include FieldKeyLogrusError when fields are valid
	buf.Reset()
	logger.WithField("valid_field", "valid_value").Info("test valid field")
	data = make(map[string]interface{})
	if err := json.Unmarshal(buf.Bytes(), &data); err != nil {
		fmt.Fprintf(os.Stderr, "assertion 3 failed to unmarshal json: %v\n", err)
		os.Exit(1)
	}
	if _, ok := data[logrus.FieldKeyLogrusError]; ok {
		fmt.Fprintf(os.Stderr, "assertion 3 failed: unexpected %q in valid log\n", logrus.FieldKeyLogrusError)
		os.Exit(1)
	}

	// 4. logrus JSONFormatter respects FieldKeyLogrusError override in FieldMap
	buf.Reset()
	customKey := "err_detail"
	customLogger := logrus.New()
	customLogger.SetOutput(buf)
	customLogger.SetFormatter(&logrus.JSONFormatter{
		FieldMap: logrus.FieldMap{
			logrus.FieldKeyLogrusError: customKey,
		},
	})
	customLogger.WithField("bad_fn", func() {}).Info("test custom field map")
	data = make(map[string]interface{})
	if err := json.Unmarshal(buf.Bytes(), &data); err != nil {
		fmt.Fprintf(os.Stderr, "assertion 4 failed to unmarshal json: %v\n", err)
		os.Exit(1)
	}
	if _, ok := data[logrus.FieldKeyLogrusError]; ok {
		fmt.Fprintf(os.Stderr, "assertion 4 failed: default key %q should not be present\n", logrus.FieldKeyLogrusError)
		os.Exit(1)
	}
	if _, ok := data[customKey]; !ok {
		fmt.Fprintf(os.Stderr, "assertion 4 failed: custom key %q not found\n", customKey)
		os.Exit(1)
	}

	// 5. logrus prefixFieldClashes prefixes user-provided FieldKeyLogrusError with fields.
	buf.Reset()
	clashLogger := logrus.New()
	clashLogger.SetOutput(buf)
	clashLogger.SetFormatter(&logrus.JSONFormatter{})
	clashLogger.WithField(logrus.FieldKeyLogrusError, "user_error_value").Info("test clash")
	data = make(map[string]interface{})
	if err := json.Unmarshal(buf.Bytes(), &data); err != nil {
		fmt.Fprintf(os.Stderr, "assertion 5 failed to unmarshal json: %v\n", err)
		os.Exit(1)
	}
	clashKey := "fields." + logrus.FieldKeyLogrusError
	if val, ok := data[clashKey]; !ok || val != "user_error_value" {
		fmt.Fprintf(os.Stderr, "assertion 5 failed: expected %q to be 'user_error_value', got %v\n", clashKey, val)
		os.Exit(1)
	}

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