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Question 32 of 100
Intermediate API Testing
Intermediate
Q32: How Do You Test and Handle Authentication Failures in APIs?
🚨Core Concept
How Do You Test and Handle Authentication Failures in APIs?
Key Takeaways & Architecture Summary
- ✓Verify that request calls lacking headers return HTTP 401 Unauthorized.
- ✓Confirm that invalid, expired, or malformed tokens yield HTTP 401.
- ✓Ensure error responses do not leak implementation details in payloads.
Direct Answer Summary
Handling authentication failures requires verifying that requests with missing, invalid, or expired credentials are systematically rejected with an HTTP 401 status code. Additionally, the response payload must be verified to confirm that it returns a clean error message without exposing backend stack traces.
⚠️ Senior Engineering Warning (Red Flag)
Never allow API authorization failures to return a generic HTTP 500 Internal Server Error. 500 errors indicate unhandled backend exceptions, whereas authentication checks should fail gracefully with a 401 or 403.
💡 STAR Architectural Explanation & Pro Tip
Automated test suites verify token refresh cycles by programmatically sending expired tokens first, asserting that they are blocked, and then verifying the retry logic.
PlaywrightApiTest.ts
Playwright API// Playwright test verifying graceful authentication rejection
const response = await apiContext.get('/api/v1/secure', {
headers: { 'Authorization': 'Bearer expired_token_9024' }
});
expect(response.status()).toBe(401);
const body = await response.json();
expect(body.error).toBe("Token expired");