Jeff’s Note #
Unlike generic exam dumps, ADH analyzes this scenario through the lens of a Real-World Lead Developer.
For DVA-C02 candidates, the confusion often lies in how to effectively test third-party API integrations when no sandbox environment exists. In production, this is about knowing exactly how to simulate realistic API responses inside your testing pipeline without incurring unnecessary costs or side effects. Let’s drill down.
The Certification Drill (Simulated Question) #
Scenario #
A tech startup, FinCommerce Solutions, builds a new online checkout platform that must integrate with multiple external payment gateways. Unfortunately, none of these payment partners offer a test or sandbox API environment. The development team needs to validate their platform’s API integration logic and error handling without triggering calls to the live payment gateways.
The Requirement: #
Design the most effective testing solution that allows the ecommerce platform to simulate the third-party payment APIs’ responses during development and testing phases — specifically, without making actual network calls to the third-party APIs.
The Options #
- A) Set up an Amazon API Gateway REST API with a gateway response configured for status code 200. Add response templates that include sample responses captured from the real third-party payment APIs.
- B) Set up an AWS AppSync GraphQL API with a data source configured for each third-party API. Specify an integration type of Mock. Configure integration responses by using sample responses captured from the real third-party API.
- C) Create an AWS Lambda function for each third-party API. Embed responses captured from the real third-party API. Configure Amazon Route 53 Resolver with an inbound endpoint for each Lambda function’s Amazon Resource Name (ARN).
- D) Set up an Amazon API Gateway REST API for each third-party API. Specify an integration request type of Mock. Configure integration responses by using sample responses captured from the real third-party API.
Google adsense #
leave a comment:
Correct Answer #
D
Quick Insight: The Developer Imperative #
- The crux here is simulating third-party APIs in a way that integrates seamlessly with the existing REST-based interface of the payment services. API Gateway’s built-in mock integration allows us to intercept requests and return pre-recorded responses without custom code or invoking live endpoints.
Content Locked: The Expert Analysis #
You’ve identified the answer. But do you know the implementation details that separate a Junior from a Senior?
The Expert’s Analysis #
Correct Answer #
Option D
The Winning Logic #
API Gateway supports a straightforward Mock integration type for REST APIs, which allows developers to define static, pre-configured responses without invoking backend endpoints. This is ideal when you need to simulate third-party API behavior with captured sample responses. It integrates well into CI/CD pipelines and local testing environments while keeping costs low and avoiding the risk of invoking real payment APIs during tests.
- This approach leverages native API Gateway features — no additional compute (Lambda) or complex resolver logic (AppSync) is needed.
- It maintains the REST API contract expected by the application.
- Easier to maintain and scale when multiple third-party APIs must be mocked consistently.
The Trap (Distractor Analysis): #
-
Why not A?
Setting up gateway responses withgateway responseis mainly for standardizing client error/responses, not for returning full mock responses per method. The mock integration feature (Option D) is more appropriate for simulating entire API responses. -
Why not B?
AppSync is GraphQL-based and would introduce unnecessary complexity for mocking REST-based payment APIs. Also, the product context is REST, so AppSync’s mock integration is an awkward fit. -
Why not C?
Lambda functions with Route 53 Resolver endpoints overcomplicate the solution and add operational overhead. Also, Route 53 resolver inbound endpoints aren’t designed for this use case and add unnecessary DNS complexity.
The Technical Blueprint #
# Example AWS CLI command to create a mock integration on API Gateway
aws apigateway put-integration \
--rest-api-id <api-id> \
--resource-id <resource-id> \
--http-method POST \
--type MOCK \
--request-templates '{"application/json":"{\"statusCode\": 200}"}'
# Then configure Integration Response with captured sample response mapping
aws apigateway put-integration-response \
--rest-api-id <api-id> \
--resource-id <resource-id> \
--http-method POST \
--status-code 200 \
--response-templates '{"application/json": "<sample response JSON>"}'
The Comparative Analysis #
| Option | API Complexity | Performance | Use Case |
|---|---|---|---|
| A | Medium | Moderate | Uses gateway responses mainly for error handling, limited mock capability |
| B | High | Moderate | Overkill; GraphQL mock for REST APIs not suitable |
| C | High | Lower | Complex; adds Lambda and DNS layers, not best practice |
| D | Low | High | Simple mock integration for REST APIs, most effective approach |
Real-World Application (Practitioner Insight) #
Exam Rule #
“For the exam, always pick API Gateway Mock Integration when you see REST API mocking to simulate third-party endpoints without live calls.”
Real World #
“In reality, teams often use API Gateway mocks combined with unit tests and local simulators to achieve fast, low-cost integration testing before hitting live services.”
(CTA) Stop Guessing, Start Mastering #
Disclaimer
This is a study note based on simulated scenarios for the DVA-C02 exam.