From 1fa2444daf283a3ff1ae0de4d714f98c079e3e38 Mon Sep 17 00:00:00 2001
From: Lahiru Maramba <llahiru@gmail.com>
Date: Wed, 27 May 2026 11:52:53 -0400
Subject: [PATCH] fix: resolve failing getApplicationDefault unit tests in
 gcloud SDK environment

---
 src/utils/crypto-signer.ts                |  2 +-
 test/unit/app/credential-internal.spec.ts | 28 ++++++++++++++++++-----
 test/unit/utils/crypto-signer.spec.ts     |  1 -
 3 files changed, 23 insertions(+), 8 deletions(-)

diff --git a/src/utils/crypto-signer.ts b/src/utils/crypto-signer.ts
index ffa23d26a8..7ff00d5297 100644
--- a/src/utils/crypto-signer.ts
+++ b/src/utils/crypto-signer.ts
@@ -79,7 +79,7 @@ export class ServiceAccountSigner implements CryptoSigner {
    * @inheritDoc
    */
   public sign(buffer: Buffer): Promise<Buffer> {
-    const crypto = require('node:crypto'); // eslint-disable-line @typescript-eslint/no-var-requires
+    const crypto = require('node:crypto');
     const sign = crypto.createSign('RSA-SHA256');
     sign.update(buffer);
     return Promise.resolve(sign.sign(this.credential.privateKey));
diff --git a/test/unit/app/credential-internal.spec.ts b/test/unit/app/credential-internal.spec.ts
index 2d56a74dd0..b269735921 100644
--- a/test/unit/app/credential-internal.spec.ts
+++ b/test/unit/app/credential-internal.spec.ts
@@ -26,6 +26,7 @@ import * as chai from 'chai';
 import * as sinon from 'sinon';
 import * as sinonChai from 'sinon-chai';
 import * as chaiAsPromised from 'chai-as-promised';
+import { UserRefreshClient } from 'google-auth-library';
 
 import * as mocks from '../../resources/mocks';
 
@@ -68,11 +69,16 @@ describe('Credential', () => {
 
   beforeEach(() => {
     mockCertificateObject = _.clone(mocks.certificateObject);
-    oldProcessEnv = process.env;
+    oldProcessEnv = { ...process.env };
   });
 
   afterEach(() => {
-    process.env = oldProcessEnv;
+    for (const key of Object.keys(process.env)) {
+      if (!(key in oldProcessEnv)) {
+        delete process.env[key];
+      }
+    }
+    Object.assign(process.env, oldProcessEnv);
   });
 
   describe('ServiceAccountCredential', () => {
@@ -310,7 +316,7 @@ describe('Credential', () => {
       expect(c).to.be.an.instanceof(ApplicationDefaultCredential);
     });
 
-    it('should return a RefreshTokenCredential with gcloud login', () => {
+    it('should return a RefreshTokenCredential with gcloud login', async () => {
       if (!fs.existsSync(GCLOUD_CREDENTIAL_PATH)) {
         // tslint:disable-next-line:no-console
         console.log(
@@ -319,7 +325,12 @@ describe('Credential', () => {
         return;
       }
       delete process.env.GOOGLE_APPLICATION_CREDENTIALS;
-      expect((getApplicationDefault())).to.be.an.instanceof(RefreshTokenCredential);
+      const c = getApplicationDefault();
+      expect(c).to.be.an.instanceof(ApplicationDefaultCredential);
+
+      process.env.GOOGLE_CLOUD_PROJECT = 'mock-project';
+      const client = await (c as any).googleAuth.getClient();
+      expect(client).to.be.an.instanceof(UserRefreshClient);
     });
 
     it('should return a MetadataServiceCredential as a last resort', () => {
@@ -345,7 +356,7 @@ describe('Credential', () => {
       expect(isApplicationDefault(c)).to.be.true;
     });
 
-    it('should return true for credential loaded from gcloud SDK', () => {
+    it('should return true for credential loaded from gcloud SDK', async () => {
       if (!fs.existsSync(GCLOUD_CREDENTIAL_PATH)) {
         // tslint:disable-next-line:no-console
         console.log(
@@ -355,7 +366,12 @@ describe('Credential', () => {
       }
       delete process.env.GOOGLE_APPLICATION_CREDENTIALS;
       const c = getApplicationDefault();
-      expect(c).to.be.an.instanceof(RefreshTokenCredential);
+      expect(c).to.be.an.instanceof(ApplicationDefaultCredential);
+
+      process.env.GOOGLE_CLOUD_PROJECT = 'mock-project';
+      const client = await (c as any).googleAuth.getClient();
+      expect(client).to.be.an.instanceof(UserRefreshClient);
+
       expect(isApplicationDefault(c)).to.be.true;
     });
 
diff --git a/test/unit/utils/crypto-signer.spec.ts b/test/unit/utils/crypto-signer.spec.ts
index 26bfc7cb38..5c3a8999fc 100644
--- a/test/unit/utils/crypto-signer.spec.ts
+++ b/test/unit/utils/crypto-signer.spec.ts
@@ -56,7 +56,6 @@ describe('CryptoSigner', () => {
       const payload = Buffer.from('test');
       const cert = new ServiceAccountCredential(mocks.certificateObject);
 
-      // eslint-disable-next-line @typescript-eslint/no-var-requires
       const crypto = require('node:crypto');
       const rsa = crypto.createSign('RSA-SHA256');
       rsa.update(payload);