1 files changed, 48 insertions, 0 deletions
diff --git a/packages/core/src/utils/user_id.test.ts b/packages/core/src/utils/user_id.test.ts
new file mode 100644
index 00000000..81b99ef4
--- /dev/null
+++ b/packages/core/src/utils/user_id.test.ts
@@ -0,0 +1,48 @@
+/**
+ * @license
+ * Copyright 2025 Google LLC
+ * SPDX-License-Identifier: Apache-2.0
+ */
+
+import { describe, it, expect } from 'vitest';
+import { getInstallationId, getObfuscatedGoogleAccountId } from './user_id.js';
+
+describe('user_id', () => {
+  describe('getInstallationId', () => {
+    it('should return a valid UUID format string', () => {
+      const installationId = getInstallationId();
+
+      expect(installationId).toBeDefined();
+      expect(typeof installationId).toBe('string');
+      expect(installationId.length).toBeGreaterThan(0);
+
+      // Should return the same ID on subsequent calls (consistent)
+      const secondCall = getInstallationId();
+      expect(secondCall).toBe(installationId);
+    });
+  });
+
+  describe('getObfuscatedGoogleAccountId', () => {
+    it('should return a non-empty string', () => {
+      const result = getObfuscatedGoogleAccountId();
+
+      expect(result).toBeDefined();
+      expect(typeof result).toBe('string');
+      expect(result.length).toBeGreaterThan(0);
+
+      // Should be consistent on subsequent calls
+      const secondCall = getObfuscatedGoogleAccountId();
+      expect(secondCall).toBe(result);
+    });
+
+    it('should return the same as installation ID when no Google Account ID is cached', () => {
+      // In a clean test environment, there should be no cached Google Account ID
+      // so getObfuscatedGoogleAccountId should fall back to installation ID
+      const googleAccountIdResult = getObfuscatedGoogleAccountId();
+      const installationIdResult = getInstallationId();
+
+      // They should be the same when no Google Account ID is cached
+      expect(googleAccountIdResult).toBe(installationIdResult);
+    });
+  });
+});