API Integration Test. How to do it right? - NashTech Insights (2024)

• Quality Solutions
• August 12, 2024

Table of Contents

What is an Integration Test?

Integration testing is a type of software testing where components of the software are gradually integrated and then tested as a whole. Usually, these components are already working well individually. However, they may break when integrated with other elements.

By simulating real-world usage scenarios, integration testing helps uncover complex bugs, improves compatibility between modules, and enhances the overall quality and performance of the software

Types of Integration Testing

Big Bang Integration Testing: Big Bang Integration testing is an integration testing approach in which all modules are integrated and tested at once, as a singular entity. It is essentially “testing in a Big Bang fashion”.
The Big Bang integration testing process is not carried out until all components have been successfully unit tested.

Incremental Integration Testing: This testing is an approach in which 2 or more modules with closely related logic and functionality are grouped and tested first, then gradually move on to other groups of modules, instead of testing everything at once. The process ends when all modules have been integrated and tested.

• Top-Down Integration Testing: Starts by testing the top-level modules and progressively integrates and tests lower-level modules using stubs for modules yet to be integrated.
• Bottom-Up Integration Testing: It begins with the lowest-level modules and works its way up to the top, using drivers to simulate higher-level modules that are not yet integrated.
• Sandwich Integration Testing (Hybrid): Combines top-down and bottom-up approaches, allowing parallel testing processes and more flexibility in handling various module levels.

Continuous Integration Testing: Involves automatically testing changes as soon as they are integrated into the main branch of the codebase. This approach is favored in Agile and DevOps practices for its emphasis on early detection of integration issues.

The importance of integration testing lies in its ability to detect problems that are not visible during unit testing. It ensures that software components work together correctly, addressing issues related to data exchange, interface compatibility, and overall system workflow

What Is API Integration Testing?

APIintegration testing is the process of testing your integration through making sure that every component of the integration will work as intended with the API. There are many components to integration testing, including APIauthentication, pagination, rate limiting, and response bodies.

What does API integration testing solve?

When to Conduct API Integration Testing

API Integration testing should be conducted:

• After Unit Testing: Once individual components have been verified through unit testing before complete integration tests on the entire system.
• During Continuous Integration Processes: As part of an automated testing suite in continuous integration/continuous deployment (CI/CD) pipelines to ensure ongoing compatibility and functionality. For insights on how to automate API testing and how it’s shaping the landscape of modern software development, including AI, microservices, and containerization, read this article: Top Trends in API Automation Testing for 2023.
• Before Major Releases: To guarantee that all components interact seamlessly via their APIs and to prevent regression issues.

API Integration Testing In Action

In software development, understanding how to test API integration becomes critical for ensuring system interaction quality and reliability. The first step in addressing this challenge is comprehending how to test API integration, which helps identify potential issues early in the development cycle.

Let’s consider a real-life API integration testing example using a simplified scenario involving a social platform.

Scenario: Adding photos to the Favorite list

Objective: Verify that the photo the user likes is successfully added to the favorite list, ensuring communication between the Photo Library and the Favorite List services through their APIs.

Steps for API Integration Testing:

• Setup: Ensure that the User Management service has at least one registered user. Ensure that the Photo Library service lists at least one photo available.

• Test Execution: Authenticate the user using the User Management service’s API to obtain an authentication token. Fetch the photo list from the Photo Library service’s API using the obtained token to simulate a user browsing the photo. Select a photo from the list and use the Favorite (Heart button) service’s API to add the photo to the user’s favorite list, providing the necessary photo ID and user credentials (if required).

• Verification: Verify that the Favorite service returns a successful response indicating the photo has been added. Call the Favorite service’s API to retrieve the contents of the user’s favorite and confirm that it includes the added photo, verifying the correct integration between the Library Photo and Favorite services.

• Cleanup: Remove the added photo from the Favorite to reset the test environment. Invalidate the user’s session if necessary.

Importance of This Test

This test is important for the project because of:

• Ensures Interoperability: Confirms that the Library Photo and Favorite services can communicate effectively through their APIs, which is crucial for the user experience on the social platform.
• Validates Business Logic: Checks that the business logic for adding a photo to the library works as expected across different services.
• Enhances User Satisfaction: By ensuring that photos can be added to the favorite list without issues, this test helps maintain high user satisfaction and trust in the social platform.

Key Components Of API Integration Testing

• API Endpoints: The primary focus of API integration testing is endpoints, which are specific paths through which interactions with the API occur.
• Request and Response Formats: This involves scrutinizing the data sent in API requests (typically in formats like JSON or XML) and validating the structure and data of the responses.
• HTTP Methods and Status Codes: Different HTTP methods (GET, POST, PUT, DELETE, etc.) dictate how APIs interact with data. Each method should be tested to verify that it performs the intended action correctly.
• Data Validation and Schema Testing: This includes validating the data returned by the API against predefined schemas or models.
• Authentication and Authorization: Testing must ensure that APIs properly enforce authentication (verifying user identity) and authorization (user permissions).
• Error Handling: APIs should be tested for their ability to handle errors gracefully.
• Performance and Load Testing: This aspect tests how the API behaves under various load conditions, including response times, throughput, and the system’s ability to handle concurrent requests.
• Environment and Configuration Testing: APIs should be tested across different environments (development, staging, production) to ensure that they perform consistently.

Types Of API Integration Testing

• RESTful API: Testing Involves testing APIs built on Representational State Transfer (REST) architecture, known for simplicity and statelessness.
• SOAP API: Testing Focuses on Simple Object Access Protocol (SOAP) APIs, characterized by their structured format and security features.
• GraphQL API: Testing Tests GraphQL APIs that allow clients to precisely request the data they need, enhancing efficiency and flexibility.
• Webhook API: Testing Involves testing Webhook APIs, which are user-defined HTTP callbacks triggered by specific events.
• Real-Time API: Testing Tests APIs that facilitate real-time data transfer, often using technologies like WebSockets.
• OAuth API: Testing Focuses on testing APIs using OAuth for token-based authentication and authorization.

API Integration Testing Tools

• Postman: A popular tool for API testing, compatible with RESTful and SOAP APIs.
• Swagger (OpenAPI): An open-source framework for RESTful web services.
• SoapUI: A comprehensive tool for testing both SOAP and REST APIs.
• JMeter: An open-source tool primarily for performance testing, also supporting API testing.
• Curl: A command-line tool for data transfer using various protocols, useful for simple API tests.
• REST-Assured: A Java library for testing RESTful APIs.

Best Practices

Some best pratices that can help develop an effective API integration testing:

• Choose a network request mocking library when possible: should try to use specialized network request mocking libraries (such as requests_mock) for API integration tests. These libraries simulate real network interactions more accurately. They also provide the ability to isolate testing scenarios, reduce dependency on external APIs, simulate error conditions for comprehensive testing (as demonstrated in the TestAPIIntegrations class), and improve testing speed by eliminating actual network requests.
• Evaluate error handling implementations: should cover various error scenarios during API interactions to ensure that your system can handle them without crashing. For example, in the API integration tests earlier, the requests_mock code simulated an error response from the API:mock.get("", status_code=500).
• Focus on boundary values: Test extreme input values to identify unexpected behaviors and ensure that your system can gracefully handle these inputs. For instance, you can test the get_converted_price(…) function by providing extremely low or high values for product prices.
• Test for backward compatibility: Conduct tests to verify that modifications to the third-party APIs don’t disrupt existing functionality.
• Use realistic data: Create tests using real-world data scenarios. This guarantees that your system can adeptly manage real user interactions.
• Keep tests updated: Keep your tests up-to-date with evolving APIs so that they remain reliable indicators of your system’s functionality. As your codebase evolves, new features, improvements, or bug fixes may alter the behavior of your system.

Reference

API Integration Testing: How To Do It Right? (luxequality.com)

How to run API integration tests (merge.dev)

What is Integration Testing? Definition, Examples, How-to (katalon.com)

https://chatgpt.com

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