cloud.google.com/go/auth v0.18.2: CredentialsOptions

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 cloud.google.com/go/auth.CredentialsOptions in pkg:golang/cloud.google.com/go/auth@v0.18.2
Kind: HOW

Use EXACTLY these public packages and versions:
  - pkg:golang/cloud.google.com/go/auth@v0.18.2
Demonstrate these symbols/APIs:
  - cloud.google.com/go/auth.CredentialsOptions

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:sha256:601b2310e5d50b24289e85bfd552aec52a8469657e6c2e67403796ba239564d4","contract":["CredentialsOptions configures a custom TokenProvider that is delegated to by NewCredentials","CredentialsOptions configures raw credentials JSON accessible via Credentials.JSON","CredentialsOptions resolves project ID from JSON when ProjectIDProvider is nil","CredentialsOptions resolves project ID from ProjectIDProvider when provided","CredentialsOptions propagates errors from ProjectIDProvider when ProjectID is called","CredentialsOptions resolves quota project ID from QuotaProjectIDProvider when provided","CredentialsOptions resolves universe domain from UniverseDomainProvider when provided","CredentialsOptions defaults UniverseDomain to googleapis.com when UniverseDomainProvider is nil"],"goal":"verify cloud.google.com/go/auth.CredentialsOptions in pkg:golang/cloud.google.com/go/auth@v0.18.2","kind":"HOW","packages":["pkg:golang/cloud.google.com/go/auth@v0.18.2"],"schemaVersion":1,"symbols":["cloud.google.com/go/auth.CredentialsOptions"]},"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/cloud.google.com/go/auth@v0.18.2"],"schemaVersion":1,"subject":"pkg:golang/cloud.google.com/go/auth@v0.18.2","symbols":["cloud.google.com/go/auth.CredentialsOptions"],"verifierAdapter":"golang@1"}

module sample

go 1.26.6

require cloud.google.com/go/auth v0.18.2

require (
	cloud.google.com/go/compute/metadata v0.9.0 // indirect
	github.com/googleapis/gax-go/v2 v2.17.0 // indirect
	golang.org/x/sys v0.40.0 // indirect
)

cloud.google.com/go/auth v0.18.2 h1:+Nbt5Ev0xEqxlNjd6c+yYUeosQ5TtEUaNcN/3FozlaM=
cloud.google.com/go/auth v0.18.2/go.mod h1:xD+oY7gcahcu7G2SG2DsBerfFxgPAJz17zz2joOFF3M=
cloud.google.com/go/compute/metadata v0.9.0 h1:pDUj4QMoPejqq20dK0Pg2N4yG9zIkYGdBtwLoEkH9Zs=
cloud.google.com/go/compute/metadata v0.9.0/go.mod h1:E0bWwX5wTnLPedCKqk3pJmVgCBSM6qQI1yTBdEb3C10=
github.com/cespare/xxhash/v2 v2.3.0 h1:UL815xU9SqsFlibzuggzjXhog7bL6oX9BbNZnL2UFvs=
github.com/cespare/xxhash/v2 v2.3.0/go.mod h1:VGX0DQ3Q6kWi7AoAeZDth3/j3BFtOZR5XLFGgcrjCOs=
github.com/felixge/httpsnoop v1.0.4 h1:NFTV2Zj1bL4mc9sqWACXbQFVBBg2W3GPvqp8/ESS2Wg=
github.com/felixge/httpsnoop v1.0.4/go.mod h1:m8KPJKqk1gH5J9DgRY2ASl2lWCfGKXixSwevea8zH2U=
github.com/go-logr/logr v1.4.3 h1:CjnDlHq8ikf6E492q6eKboGOC0T8CDaOvkHCIg8idEI=
github.com/go-logr/logr v1.4.3/go.mod h1:9T104GzyrTigFIr8wt5mBrctHMim0Nb2HLGrmQ40KvY=
github.com/go-logr/stdr v1.2.2 h1:hSWxHoqTgW2S2qGc0LTAI563KZ5YKYRhT3MFKZMbjag=
github.com/go-logr/stdr v1.2.2/go.mod h1:mMo/vtBO5dYbehREoey6XUKy/eSumjCCveDpRre4VKE=
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/google/s2a-go v0.1.9 h1:LGD7gtMgezd8a/Xak7mEWL0PjoTQFvpRudN895yqKW0=
github.com/google/s2a-go v0.1.9/go.mod h1:YA0Ei2ZQL3acow2O62kdp9UlnvMmU7kA6Eutn0dXayM=
github.com/googleapis/enterprise-certificate-proxy v0.3.11 h1:vAe81Msw+8tKUxi2Dqh/NZMz7475yUvmRIkXr4oN2ao=
github.com/googleapis/enterprise-certificate-proxy v0.3.11/go.mod h1:RFV7MUdlb7AgEq2v7FmMCfeSMCllAzWxFgRdusoGks8=
github.com/googleapis/gax-go/v2 v2.17.0 h1:RksgfBpxqff0EZkDWYuz9q/uWsTVz+kf43LsZ1J6SMc=
github.com/googleapis/gax-go/v2 v2.17.0/go.mod h1:mzaqghpQp4JDh3HvADwrat+6M3MOIDp5YKHhb9PAgDY=
go.opentelemetry.io/auto/sdk v1.2.1 h1:jXsnJ4Lmnqd11kwkBV2LgLoFMZKizbCi5fNZ/ipaZ64=
go.opentelemetry.io/auto/sdk v1.2.1/go.mod h1:KRTj+aOaElaLi+wW1kO/DZRXwkF4C5xPbEe3ZiIhN7Y=
go.opentelemetry.io/contrib/instrumentation/net/http/otelhttp v0.61.0 h1:F7Jx+6hwnZ41NSFTO5q4LYDtJRXBf2PD0rNBkeB/lus=
go.opentelemetry.io/contrib/instrumentation/net/http/otelhttp v0.61.0/go.mod h1:UHB22Z8QsdRDrnAtX4PntOl36ajSxcdUMt1sF7Y6E7Q=
go.opentelemetry.io/otel v1.39.0 h1:8yPrr/S0ND9QEfTfdP9V+SiwT4E0G7Y5MO7p85nis48=
go.opentelemetry.io/otel v1.39.0/go.mod h1:kLlFTywNWrFyEdH0oj2xK0bFYZtHRYUdv1NklR/tgc8=
go.opentelemetry.io/otel/metric v1.39.0 h1:d1UzonvEZriVfpNKEVmHXbdf909uGTOQjA0HF0Ls5Q0=
go.opentelemetry.io/otel/metric v1.39.0/go.mod h1:jrZSWL33sD7bBxg1xjrqyDjnuzTUB0x1nBERXd7Ftcs=
go.opentelemetry.io/otel/trace v1.39.0 h1:2d2vfpEDmCJ5zVYz7ijaJdOF59xLomrvj7bjt6/qCJI=
go.opentelemetry.io/otel/trace v1.39.0/go.mod h1:88w4/PnZSazkGzz/w84VHpQafiU4EtqqlVdxWy+rNOA=
golang.org/x/crypto v0.47.0 h1:V6e3FRj+n4dbpw86FJ8Fv7XVOql7TEwpHapKoMJ/GO8=
golang.org/x/crypto v0.47.0/go.mod h1:ff3Y9VzzKbwSSEzWqJsJVBnWmRwRSHt/6Op5n9bQc4A=
golang.org/x/net v0.49.0 h1:eeHFmOGUTtaaPSGNmjBKpbng9MulQsJURQUAfUwY++o=
golang.org/x/net v0.49.0/go.mod h1:/ysNB2EvaqvesRkuLAyjI1ycPZlQHM3q01F02UY/MV8=
golang.org/x/sys v0.40.0 h1:DBZZqJ2Rkml6QMQsZywtnjnnGvHza6BTfYFWY9kjEWQ=
golang.org/x/sys v0.40.0/go.mod h1:OgkHotnGiDImocRcuBABYBEXf8A9a87e/uXjp9XT3ks=
golang.org/x/text v0.33.0 h1:B3njUFyqtHDUI5jMn1YIr5B0IE2U0qck04r6d4KPAxE=
golang.org/x/text v0.33.0/go.mod h1:LuMebE6+rBincTi9+xWTY8TztLzKHc/9C1uBCG27+q8=
google.golang.org/genproto v0.0.0-20260128011058-8636f8732409 h1:VQZ/yAbAtjkHgH80teYd2em3xtIkkHd7ZhqfH2N9CsM=
google.golang.org/genproto/googleapis/rpc v0.0.0-20260128011058-8636f8732409 h1:H86B94AW+VfJWDqFeEbBPhEtHzJwJfTbgE2lZa54ZAQ=
google.golang.org/genproto/googleapis/rpc v0.0.0-20260128011058-8636f8732409/go.mod h1:j9x/tPzZkyxcgEFkiKEEGxfvyumM01BEtsW8xzOahRQ=
google.golang.org/grpc v1.78.0 h1:K1XZG/yGDJnzMdd/uZHAkVqJE+xIDOcmdSFZkBUicNc=
google.golang.org/grpc v1.78.0/go.mod h1:I47qjTo4OKbMkjA/aOOwxDIiPSBofUtQUI5EfpWvW7U=
google.golang.org/protobuf v1.36.11 h1:fV6ZwhNocDyBLK0dj+fg8ektcVegBBuEolpbTQyBNVE=
google.golang.org/protobuf v1.36.11/go.mod h1:HTf+CrKn2C3g5S8VImy6tdcUvCska2kB7j23XfzDpco=

package main

import (
	"context"
	"fmt"
	"log"
	"time"

	"cloud.google.com/go/auth"
)

type staticTokenProvider struct {
	token *auth.Token
}

func (p *staticTokenProvider) Token(ctx context.Context) (*auth.Token, error) {
	return p.token, nil
}

func main() {
	ctx := context.Background()

	mockToken := &auth.Token{
		Value:  "example-token-value",
		Type:   "Bearer",
		Expiry: time.Now().Add(1 * time.Hour),
	}

	opts := &auth.CredentialsOptions{
		TokenProvider: &staticTokenProvider{token: mockToken},
		JSON:          []byte(`{"type":"service_account","project_id":"sample-project"}`),
		ProjectIDProvider: auth.CredentialsPropertyFunc(func(ctx context.Context) (string, error) {
			return "configured-project-id", nil
		}),
		QuotaProjectIDProvider: auth.CredentialsPropertyFunc(func(ctx context.Context) (string, error) {
			return "configured-quota-project-id", nil
		}),
		UniverseDomainProvider: auth.CredentialsPropertyFunc(func(ctx context.Context) (string, error) {
			return "example.com", nil
		}),
	}

	creds := auth.NewCredentials(opts)

	tok, err := creds.Token(ctx)
	if err != nil {
		log.Fatalf("failed to get token: %v", err)
	}
	fmt.Printf("Token Value: %s\n", tok.Value)

	projectID, err := creds.ProjectID(ctx)
	if err != nil {
		log.Fatalf("failed to get project ID: %v", err)
	}
	fmt.Printf("Project ID: %s\n", projectID)

	quotaProjectID, err := creds.QuotaProjectID(ctx)
	if err != nil {
		log.Fatalf("failed to get quota project ID: %v", err)
	}
	fmt.Printf("Quota Project ID: %s\n", quotaProjectID)

	universeDomain, err := creds.UniverseDomain(ctx)
	if err != nil {
		log.Fatalf("failed to get universe domain: %v", err)
	}
	fmt.Printf("Universe Domain: %s\n", universeDomain)
}

{
  "schemaVersion": 1,
  "goal": "verify cloud.google.com/go/auth.CredentialsOptions in pkg:golang/cloud.google.com/go/auth@v0.18.2",
  "kind": "HOW",
  "packages": [
    "pkg:golang/cloud.google.com/go/auth@v0.18.2"
  ],
  "symbols": [
    "cloud.google.com/go/auth.CredentialsOptions"
  ]
}

package main

import (
	"bytes"
	"context"
	"errors"
	"fmt"
	"os"
	"time"

	"cloud.google.com/go/auth"
)

type staticTokenProvider struct {
	token *auth.Token
	err   error
}

func (p *staticTokenProvider) Token(ctx context.Context) (*auth.Token, error) {
	return p.token, p.err
}

func main() {
	ctx := context.Background()

	// 1. CredentialsOptions configures a custom TokenProvider that is delegated to by NewCredentials
	{
		expectedToken := &auth.Token{
			Value:  "contract-token-value",
			Type:   "Bearer",
			Expiry: time.Now().Add(1 * time.Hour),
		}
		opts := &auth.CredentialsOptions{
			TokenProvider: &staticTokenProvider{token: expectedToken},
		}
		creds := auth.NewCredentials(opts)
		tok, err := creds.Token(ctx)
		if err != nil {
			fmt.Fprintf(os.Stderr, "assertion 1 failed with error: %v\n", err)
			os.Exit(1)
		}
		if tok.Value != expectedToken.Value || tok.Type != expectedToken.Type {
			fmt.Fprintf(os.Stderr, "assertion 1 failed: expected token %+v, got %+v\n", expectedToken, tok)
			os.Exit(1)
		}
	}

	// 2. CredentialsOptions configures raw credentials JSON accessible via Credentials.JSON
	{
		rawJSON := []byte(`{"type":"service_account","project_id":"sample-project-id"}`)
		opts := &auth.CredentialsOptions{
			TokenProvider: &staticTokenProvider{},
			JSON:          rawJSON,
		}
		creds := auth.NewCredentials(opts)
		if !bytes.Equal(creds.JSON(), rawJSON) {
			fmt.Fprintf(os.Stderr, "assertion 2 failed: expected JSON %s, got %s\n", string(rawJSON), string(creds.JSON()))
			os.Exit(1)
		}
	}

	// 3. CredentialsOptions resolves project ID from JSON when ProjectIDProvider is nil
	{
		rawJSON := []byte(`{"type":"service_account","project_id":"sample-json-proj"}`)
		opts := &auth.CredentialsOptions{
			TokenProvider:     &staticTokenProvider{},
			JSON:              rawJSON,
			ProjectIDProvider: nil,
		}
		creds := auth.NewCredentials(opts)
		projectID, err := creds.ProjectID(ctx)
		if err != nil {
			fmt.Fprintf(os.Stderr, "assertion 3 failed with error: %v\n", err)
			os.Exit(1)
		}
		if projectID != "sample-json-proj" {
			fmt.Fprintf(os.Stderr, "assertion 3 failed: expected sample-json-proj, got %s\n", projectID)
			os.Exit(1)
		}
	}

	// 4. CredentialsOptions resolves project ID from ProjectIDProvider when provided
	{
		opts := &auth.CredentialsOptions{
			TokenProvider: &staticTokenProvider{},
			ProjectIDProvider: auth.CredentialsPropertyFunc(func(ctx context.Context) (string, error) {
				return "dynamic-project-id", nil
			}),
		}
		creds := auth.NewCredentials(opts)
		projectID, err := creds.ProjectID(ctx)
		if err != nil {
			fmt.Fprintf(os.Stderr, "assertion 4 failed with error: %v\n", err)
			os.Exit(1)
		}
		if projectID != "dynamic-project-id" {
			fmt.Fprintf(os.Stderr, "assertion 4 failed: expected dynamic-project-id, got %s\n", projectID)
			os.Exit(1)
		}
	}

	// 5. CredentialsOptions propagates errors from ProjectIDProvider when ProjectID is called
	{
		expectedErr := errors.New("project lookup failed")
		opts := &auth.CredentialsOptions{
			TokenProvider: &staticTokenProvider{},
			ProjectIDProvider: auth.CredentialsPropertyFunc(func(ctx context.Context) (string, error) {
				return "", expectedErr
			}),
		}
		creds := auth.NewCredentials(opts)
		_, err := creds.ProjectID(ctx)
		if !errors.Is(err, expectedErr) {
			fmt.Fprintf(os.Stderr, "assertion 5 failed: expected error %v, got %v\n", expectedErr, err)
			os.Exit(1)
		}
	}

	// 6. CredentialsOptions resolves quota project ID from QuotaProjectIDProvider when provided
	{
		opts := &auth.CredentialsOptions{
			TokenProvider: &staticTokenProvider{},
			QuotaProjectIDProvider: auth.CredentialsPropertyFunc(func(ctx context.Context) (string, error) {
				return "quota-project-id", nil
			}),
		}
		creds := auth.NewCredentials(opts)
		quotaProjectID, err := creds.QuotaProjectID(ctx)
		if err != nil {
			fmt.Fprintf(os.Stderr, "assertion 6 failed with error: %v\n", err)
			os.Exit(1)
		}
		if quotaProjectID != "quota-project-id" {
			fmt.Fprintf(os.Stderr, "assertion 6 failed: expected quota-project-id, got %s\n", quotaProjectID)
			os.Exit(1)
		}
	}

	// 7. CredentialsOptions resolves universe domain from UniverseDomainProvider when provided
	{
		opts := &auth.CredentialsOptions{
			TokenProvider: &staticTokenProvider{},
			UniverseDomainProvider: auth.CredentialsPropertyFunc(func(ctx context.Context) (string, error) {
				return "example.com", nil
			}),
		}
		creds := auth.NewCredentials(opts)
		universeDomain, err := creds.UniverseDomain(ctx)
		if err != nil {
			fmt.Fprintf(os.Stderr, "assertion 7 failed with error: %v\n", err)
			os.Exit(1)
		}
		if universeDomain != "example.com" {
			fmt.Fprintf(os.Stderr, "assertion 7 failed: expected example.com, got %s\n", universeDomain)
			os.Exit(1)
		}
	}

	// 8. CredentialsOptions defaults UniverseDomain to googleapis.com when UniverseDomainProvider is nil
	{
		opts := &auth.CredentialsOptions{
			TokenProvider:          &staticTokenProvider{},
			UniverseDomainProvider: nil,
		}
		creds := auth.NewCredentials(opts)
		universeDomain, err := creds.UniverseDomain(ctx)
		if err != nil {
			fmt.Fprintf(os.Stderr, "assertion 8 failed with error: %v\n", err)
			os.Exit(1)
		}
		if universeDomain != "googleapis.com" {
			fmt.Fprintf(os.Stderr, "assertion 8 failed: expected googleapis.com, got %s\n", universeDomain)
			os.Exit(1)
		}
	}

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