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

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.NewCredentials 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.NewCredentials

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:sha256:50370b8316b4b5bb74a25332cb0ffd55817ec0bf423030ddfe0593bdbfe1233c","contract":["NewCredentials wraps a custom TokenProvider and delegates Token retrieval","NewCredentials retains raw JSON credential payload accessible via JSON()","NewCredentials resolves default universe domain googleapis.com when no provider is configured","NewCredentials delegates project and quota project resolution to configured property providers"],"goal":"verify cloud.google.com/go/auth.NewCredentials 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.NewCredentials"]},"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.NewCredentials"],"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"
	"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() {
	tp := &staticTokenProvider{
		token: &auth.Token{
			Value:  "sample-token-value",
			Type:   "Bearer",
			Expiry: time.Now().Add(1 * time.Hour),
		},
	}

	creds := auth.NewCredentials(&auth.CredentialsOptions{
		TokenProvider: tp,
		JSON:          []byte(`{"type": "service_account", "project_id": "example-project"}`),
	})

	ctx := context.Background()
	tok, err := creds.Token(ctx)
	if err != nil {
		fmt.Printf("Token error: %v\n", err)
		return
	}
	fmt.Printf("Token type: %s, valid: %v\n", tok.Type, tok.IsValid())

	projectID, err := creds.ProjectID(ctx)
	if err != nil {
		fmt.Printf("ProjectID error: %v\n", err)
		return
	}
	fmt.Printf("Project ID: %s\n", projectID)

	domain, err := creds.UniverseDomain(ctx)
	if err != nil {
		fmt.Printf("UniverseDomain error: %v\n", err)
		return
	}
	fmt.Printf("Universe domain: %s\n", domain)
}

{
  "schemaVersion": 1,
  "goal": "verify cloud.google.com/go/auth.NewCredentials 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.NewCredentials"
  ]
}

package main

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

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

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

func (m *mockTokenProvider) Token(ctx context.Context) (*auth.Token, error) {
	if m.err != nil {
		return nil, m.err
	}
	return m.token, nil
}

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

	// Assertion 1: NewCredentials wraps a custom TokenProvider and delegates Token retrieval
	{
		expectedToken := &auth.Token{
			Value:  "mock-access-token-12345",
			Type:   "Bearer",
			Expiry: time.Now().Add(time.Hour),
		}
		creds := auth.NewCredentials(&auth.CredentialsOptions{
			TokenProvider: &mockTokenProvider{token: expectedToken},
		})
		gotToken, err := creds.Token(ctx)
		if err != nil {
			fmt.Fprintf(os.Stderr, "Assertion 1 failed: unexpected error: %v\n", err)
			os.Exit(1)
		}
		if gotToken.Value != expectedToken.Value || gotToken.Type != expectedToken.Type {
			fmt.Fprintf(os.Stderr, "Assertion 1 failed: expected token %v, got %v\n", expectedToken, gotToken)
			os.Exit(1)
		}
		if !gotToken.IsValid() {
			fmt.Fprintf(os.Stderr, "Assertion 1 failed: expected token to be valid\n")
			os.Exit(1)
		}
	}

	// Assertion 2: NewCredentials retains raw JSON credential payload accessible via JSON()
	{
		rawJSON := []byte(`{"type":"authorized_user","client_id":"example-client-id"}`)
		creds := auth.NewCredentials(&auth.CredentialsOptions{
			TokenProvider: &mockTokenProvider{token: &auth.Token{Value: "token"}},
			JSON:          rawJSON,
		})
		gotJSON := creds.JSON()
		if !bytes.Equal(gotJSON, rawJSON) {
			fmt.Fprintf(os.Stderr, "Assertion 2 failed: expected %s, got %s\n", string(rawJSON), string(gotJSON))
			os.Exit(1)
		}
	}

	// Assertion 3: NewCredentials resolves default universe domain googleapis.com when no provider is configured
	{
		creds := auth.NewCredentials(&auth.CredentialsOptions{
			TokenProvider: &mockTokenProvider{token: &auth.Token{Value: "token"}},
		})
		domain, err := creds.UniverseDomain(ctx)
		if err != nil {
			fmt.Fprintf(os.Stderr, "Assertion 3 failed: unexpected error: %v\n", err)
			os.Exit(1)
		}
		if domain != "googleapis.com" {
			fmt.Fprintf(os.Stderr, "Assertion 3 failed: expected googleapis.com, got %q\n", domain)
			os.Exit(1)
		}
	}

	// Assertion 4: NewCredentials delegates project and quota project resolution to configured property providers
	{
		expectedProject := "test-custom-project"
		expectedQuota := "test-quota-project"
		creds := auth.NewCredentials(&auth.CredentialsOptions{
			TokenProvider: &mockTokenProvider{token: &auth.Token{Value: "token"}},
			ProjectIDProvider: auth.CredentialsPropertyFunc(func(ctx context.Context) (string, error) {
				return expectedProject, nil
			}),
			QuotaProjectIDProvider: auth.CredentialsPropertyFunc(func(ctx context.Context) (string, error) {
				return expectedQuota, nil
			}),
		})
		project, err := creds.ProjectID(ctx)
		if err != nil {
			fmt.Fprintf(os.Stderr, "Assertion 4 failed: ProjectID error: %v\n", err)
			os.Exit(1)
		}
		if project != expectedProject {
			fmt.Fprintf(os.Stderr, "Assertion 4 failed: expected project %q, got %q\n", expectedProject, project)
			os.Exit(1)
		}

		quota, err := creds.QuotaProjectID(ctx)
		if err != nil {
			fmt.Fprintf(os.Stderr, "Assertion 4 failed: QuotaProjectID error: %v\n", err)
			os.Exit(1)
		}
		if quota != expectedQuota {
			fmt.Fprintf(os.Stderr, "Assertion 4 failed: expected quota %q, got %q\n", expectedQuota, quota)
			os.Exit(1)
		}
	}

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