go.opentelemetry.io/otel/trace v1.37.0: EventOption

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.opentelemetry.io/otel/trace.EventOption in pkg:golang/go.opentelemetry.io/otel/trace@v1.37.0
Kind: HOW

Use EXACTLY these public packages and versions:
  - pkg:golang/go.opentelemetry.io/otel/trace@v1.37.0
Demonstrate these symbols/APIs:
  - go.opentelemetry.io/otel/trace.EventOption

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:sha256:10f7465a36273e1ccdbf13f84822580efc2116acb73bc7b22b0efe863c4dcfca","contract":["NewEventConfig without options assigns a non-zero call timestamp, empty attributes, and false stack trace flag","WithAttributes option applies attributes to EventConfig and multiple calls append in order without overwriting","WithTimestamp option sets explicit timestamp on EventConfig","WithStackTrace option sets stack trace capture flag on EventConfig","Span AddEvent and RecordError accept EventOption options including WithAttributes, WithTimestamp, and WithStackTrace"],"goal":"verify go.opentelemetry.io/otel/trace.EventOption in pkg:golang/go.opentelemetry.io/otel/trace@v1.37.0","kind":"HOW","packages":["pkg:golang/go.opentelemetry.io/otel/trace@v1.37.0"],"schemaVersion":1,"symbols":["go.opentelemetry.io/otel/trace.EventOption"]},"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.opentelemetry.io/otel/trace@v1.37.0"],"schemaVersion":1,"subject":"pkg:golang/go.opentelemetry.io/otel/trace@v1.37.0","symbols":["go.opentelemetry.io/otel/trace.EventOption"],"verifierAdapter":"golang@1"}

module sample

go 1.26.6

require (
	go.opentelemetry.io/otel v1.37.0
	go.opentelemetry.io/otel/trace v1.37.0
)

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/go-cmp v0.7.0 h1:wk8382ETsv4JYUZwIsn6YpYiWiBsYLSJiTsyBybVuN8=
github.com/google/go-cmp v0.7.0/go.mod h1:pXiqmnSA92OHEEa9HXL2W4E7lf9JzCmGVUdgjX3N/iU=
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 v1.10.0 h1:Xv5erBjTwe/5IxqUQTdXv5kgmIvbHo3QQyRwhJsOfJA=
github.com/stretchr/testify v1.10.0/go.mod h1:r2ic/lqez/lEtzL7wO/rwa5dbSLXVDPFyf8C91i36aY=
go.opentelemetry.io/otel v1.37.0 h1:9zhNfelUvx0KBfu/gb+ZgeAfAgtWrfHJZcAqFC228wQ=
go.opentelemetry.io/otel v1.37.0/go.mod h1:ehE/umFRLnuLa/vSccNq9oS1ErUlkkK71gMcN34UG8I=
go.opentelemetry.io/otel/trace v1.37.0 h1:HLdcFNbRQBE2imdSEgm/kwqmQj1Or1l/7bW6mxVK7z4=
go.opentelemetry.io/otel/trace v1.37.0/go.mod h1:TlgrlQ+PtQO5XFerSPUYG0JSgGyryXewPGyayAWSBS0=
gopkg.in/yaml.v3 v3.0.1 h1:fxVm/GzAzEWqLHuvctI91KS9hhNmmWOoWu0XTYJS7CA=
gopkg.in/yaml.v3 v3.0.1/go.mod h1:K4uyk7z7BCEPqu6E+C64Yfv1cQ7kz7rIZviUmN+EgEM=

package main

import (
	"context"
	"fmt"
	"time"

	"go.opentelemetry.io/otel/attribute"
	"go.opentelemetry.io/otel/trace"
)

func main() {
	tp := trace.NewNoopTracerProvider()
	tracer := tp.Tracer("event-sample")

	_, span := tracer.Start(context.Background(), "sample-operation")
	defer span.End()

	eventTime := time.Now()
	span.AddEvent("cache_lookup",
		trace.WithTimestamp(eventTime),
		trace.WithAttributes(
			attribute.String("cache.key", "user:123"),
			attribute.Bool("cache.hit", false),
		),
	)

	sampleErr := fmt.Errorf("simulated failure")
	span.RecordError(sampleErr,
		trace.WithStackTrace(true),
		trace.WithTimestamp(time.Now()),
		trace.WithAttributes(attribute.String("error.severity", "warning")),
	)

	opts := []trace.EventOption{
		trace.WithTimestamp(eventTime),
		trace.WithAttributes(attribute.String("status", "ready")),
		trace.WithStackTrace(false),
	}
	cfg := trace.NewEventConfig(opts...)

	fmt.Printf("EventConfig timestamp: %v, stackTrace: %v, attributes: %d\n",
		cfg.Timestamp(), cfg.StackTrace(), len(cfg.Attributes()))
}

{
  "schemaVersion": 1,
  "goal": "verify go.opentelemetry.io/otel/trace.EventOption in pkg:golang/go.opentelemetry.io/otel/trace@v1.37.0",
  "kind": "HOW",
  "packages": [
    "pkg:golang/go.opentelemetry.io/otel/trace@v1.37.0"
  ],
  "symbols": [
    "go.opentelemetry.io/otel/trace.EventOption"
  ]
}

package main

import (
	"context"
	"fmt"
	"os"
	"time"

	"go.opentelemetry.io/otel/attribute"
	"go.opentelemetry.io/otel/trace"
)

func main() {
	// Assertion 1: NewEventConfig without options assigns a non-zero call timestamp, empty attributes, and false stack trace flag
	{
		cfg := trace.NewEventConfig()
		if cfg.Timestamp().IsZero() {
			fmt.Fprintf(os.Stderr, "assertion 1 failed: expected non-zero timestamp\n")
			os.Exit(1)
		}
		if len(cfg.Attributes()) != 0 {
			fmt.Fprintf(os.Stderr, "assertion 1 failed: expected 0 attributes, got %d\n", len(cfg.Attributes()))
			os.Exit(1)
		}
		if cfg.StackTrace() {
			fmt.Fprintf(os.Stderr, "assertion 1 failed: expected stackTrace to be false\n")
			os.Exit(1)
		}
	}

	// Assertion 2: WithAttributes option applies attributes to EventConfig and multiple calls append in order without overwriting
	{
		attr1 := attribute.String("env", "production")
		attr2 := attribute.Int("code", 200)
		attr3 := attribute.Bool("retryable", false)

		cfg := trace.NewEventConfig(
			trace.WithAttributes(attr1, attr2),
			trace.WithAttributes(attr3),
		)

		attrs := cfg.Attributes()
		if len(attrs) != 3 {
			fmt.Fprintf(os.Stderr, "assertion 2 failed: expected 3 attributes, got %d\n", len(attrs))
			os.Exit(1)
		}
		if attrs[0] != attr1 || attrs[1] != attr2 || attrs[2] != attr3 {
			fmt.Fprintf(os.Stderr, "assertion 2 failed: attributes mismatch: %+v\n", attrs)
			os.Exit(1)
		}
	}

	// Assertion 3: WithTimestamp option sets explicit timestamp on EventConfig
	{
		t1 := time.Date(2026, time.September, 17, 10, 0, 0, 0, time.UTC)
		t2 := time.Date(2026, time.September, 17, 10, 5, 0, 0, time.UTC)

		cfg1 := trace.NewEventConfig(trace.WithTimestamp(t1))
		if !cfg1.Timestamp().Equal(t1) {
			fmt.Fprintf(os.Stderr, "assertion 3 failed: expected %v, got %v\n", t1, cfg1.Timestamp())
			os.Exit(1)
		}

		// Multiple calls overwrite with last-one-wins
		cfg2 := trace.NewEventConfig(trace.WithTimestamp(t1), trace.WithTimestamp(t2))
		if !cfg2.Timestamp().Equal(t2) {
			fmt.Fprintf(os.Stderr, "assertion 3 failed: expected last timestamp %v, got %v\n", t2, cfg2.Timestamp())
			os.Exit(1)
		}
	}

	// Assertion 4: WithStackTrace option sets stack trace capture flag on EventConfig
	{
		cfgFalse := trace.NewEventConfig(trace.WithStackTrace(false))
		if cfgFalse.StackTrace() {
			fmt.Fprintf(os.Stderr, "assertion 4 failed: expected stackTrace false\n")
			os.Exit(1)
		}

		cfgTrue := trace.NewEventConfig(trace.WithStackTrace(true))
		if !cfgTrue.StackTrace() {
			fmt.Fprintf(os.Stderr, "assertion 4 failed: expected stackTrace true\n")
			os.Exit(1)
		}

		// Multiple calls overwrite with last-one-wins
		cfgOverride := trace.NewEventConfig(trace.WithStackTrace(true), trace.WithStackTrace(false))
		if cfgOverride.StackTrace() {
			fmt.Fprintf(os.Stderr, "assertion 4 failed: expected stackTrace false after overwrite\n")
			os.Exit(1)
		}
	}

	// Assertion 5: Span AddEvent and RecordError accept EventOption options including WithAttributes, WithTimestamp, and WithStackTrace
	{
		tp := trace.NewNoopTracerProvider()
		tracer := tp.Tracer("contract-tracer")
		_, span := tracer.Start(context.Background(), "test-span")
		defer span.End()

		eventTime := time.Date(2026, time.September, 17, 11, 0, 0, 0, time.UTC)
		eventOpts := []trace.EventOption{
			trace.WithTimestamp(eventTime),
			trace.WithAttributes(attribute.String("event.name", "checkpoint")),
		}
		span.AddEvent("checkpoint", eventOpts...)

		errOpts := []trace.EventOption{
			trace.WithTimestamp(eventTime),
			trace.WithStackTrace(true),
			trace.WithAttributes(attribute.String("error.type", "test_error")),
		}
		span.RecordError(fmt.Errorf("simulated contract error"), errOpts...)
	}

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