Complete Guide to APIs: Build, Test and Deploy
DevSamurai
Atlassian Marketplace Vendor, Certified Kubernetes Service Provider, Google Cloud Service Partner
Modern development is not just about writing code – it is about building reliable, testable APIs that work right from the start. This blog will walk you through the smart way to design, test, and deploy APIs, helping you avoid common mistakes and deliver quality software faster.
Read full article here: Complete Guide
Building & Testing APIs
Now that we understand the importance of API development, let’s explore two fundamental approaches that shape how we build and test these interfaces. Developers utilize two primary development approaches: Test-Driven Development (TDD) and Behavior-Driven Development (BDD).
BDD focuses on building the code first, followed by testing, which may result in delayed issue identification and reactive rather than proactive problem-solving. In contrast, TDD involves writing tests first, based on the anticipated behavior of the API. Only after the tests fail is the API code developed to pass them. This iterative approach helps detect errors early and ensures that development stays aligned with requirements from the outset.
In API testing, Test-Driven Development (TDD) is often favored to ensure the API meets specific functional requirements from the beginning:
In TDD, the RED, GREEN, and BLUE stages represent the key phases of the TDD cycle.
What is API
But first, what is API? APIs, or Application Programming Interfaces, allow two software programs to communicate by following specific rules and definitions. For example, The User is like a diner placing an order, the API is the waiter passing requests between the user and the Application, which acts as the kitchen preparing the response.
The “Application” in API refers to any software designed to perform a particular task, while the “Interface” is the set of rules that defines how two applications communicate with each other. This communication happens through organized requests and responses, and developers use API documentation to make sure different systems interact correctly.
APIs let different software systems communicate, and API testing ensures this communication works correctly. It checks that data exchanges happen as expected, ensuring reliability.
API Design
Now that you have an understanding of API fundamentals, let’s dive into effective design strategies. There are four essential steps in the API design process that every organization should follow. Each step involves collaboration among key stakeholders—such as business leaders, developers, users, and partners—to ensure the API addresses all necessary requirements. Working together throughout the process helps avoid creating unnecessary features.
SOAP vs REST API Design
With the design principles established, we now face a crucial decision in API architecture. API design choices between REST and SOAP depend on specific application needs.
REST (Representational State Transfer) offers a flexible and lightweight approach to API design. It relies on standard HTTP methods like GET and POST and supports data formats like JSON and XML. REST works well for web-based applications that emphasize performance, scalability, and simplicity, making it straightforward for developers to implement and maintain.
In contrast, SOAP (Simple Object Access Protocol) follows a protocol-based design using XML for message formatting. It is more structured, providing built-in error handling and enhanced security features, which makes it well-suited for enterprise applications with stringent security needs.
→ Related content: Top REST API Testing Tools
Test Writing
Moving from design to implementation, the next critical phase involves creating comprehensive test cases. In the test-writing stage of Test-Driven Development (TDD), tests are created before any code is written. These tests specify the expected behavior of the API or software feature. Initially, the tests will fail since the code to fulfill them doesn’t yet exist—this phase is known as the RED phase. As developers build the functionality, they adjust the code to ensure it passes these tests, confirming the API behaves as intended. This approach directs the development process, helping to catch errors early and keep the software aligned with expected outcomes.
→ Related content: Write Test Cases for Automated Tests
Conduct Manual API Test Cases
A manual API test case is a structured procedure that a tester follows to validate an API’s functionality under specific conditions. The key components include:
Each test case has a clear objective, outlining its purpose, along with test data, such as valid and invalid inputs. The execution steps describe how to perform the test, while the expected results, like status codes or response formats, indicate what should happen. The pass/fail criteria then compares the actual outcomes to the expected results to verify that the API behaves as intended, ensuring it handles requests properly and delivers accurate responses.
→ Related content: How to Write and Execute a test case in 5 Minutes
Rather than using a spreadsheet to document test cases and steps, testers today can benefit from tools like AgileTest, a Jira application. AgileTest optimizes the management of both manual and automated test cases by providing a centralized, organized platform to track and run tests. It supports various types of testing, helping teams boost productivity and manage the test lifecycle more efficiently.
In AgileTest, you can write manual API test cases by manually adding individual test steps or by using the AI Generator feature. The AI Generator takes the API design details provided in the description and automatically generates multiple test cases based on your API’s specific requirements. This feature simplifies the process, ensuring thorough test coverage and reducing the manual effort involved in testing complex API specifications.
→ Related content: Test Cases, Test Steps & How to generate with AI?
API Development
Once we have our test cases in place, we can proceed with the actual development phase. In the GREEN phase of Test-Driven Development (TDD) for APIs, the focus shifts to developing the API after writing failing tests during the RED phase.
The process includes the following steps:
In TDD, the Refactoring (BLUE) phase involves cleaning up and optimizing the code after ensuring all tests pass in the GREEN phase. Once the functionality works correctly, the goal is to improve the code’s structure, making it more efficient, readable, and maintainable, without altering its behavior. This step involves tasks like eliminating redundancies, enhancing performance, or organizing the code for better long-term scalability, all while ensuring no tests fail during the process.
What is API Testing?
After development, thorough testing becomes paramount for ensuring reliability. API testing involves assessing the APIs that enable communication between different software systems. It focuses on evaluating critical aspects like core functionality, data formats, error handling, and server responses. While API testing shares similarities with other software testing methods, it places particular emphasis on validating server responses and ensuring proper data handling.
The process includes sending various requests to API endpoints for performance testing, writing unit tests to verify the business logic, and conducting security tests to protect against potential attacks. Additionally, it involves checking endpoints, request methods, headers, rate limits, and other important factors to ensure the API performs as expected.
Common API testing types:
API testing includes several common types, each serving a specific purpose:
These testing methods help ensure that APIs operate efficiently, securely, and as expected across different conditions.
The Importance of API Testing
When APIs perform poorly, users may experience slow response times, timeouts, or unresponsive behavior, which negatively impacts the overall user experience. This can lead to increased bounce rates, decreased user retention, and negative feedback, all of which can damage the app’s reputation and success. Therefore, thorough API performance testing is crucial to identify and fix performance issues before they affect users.
Process Used in API Testing
The API testing process is crucial for ensuring that an API functions as expected. Below is a structured approach to conducting API testing:
1. Review API Documentation
Begin by thoroughly reviewing the API documentation. Understand its purpose, endpoints, input parameters, and expected outputs to gain clarity on how the API should function.
2. Categorize Endpoints and Flows
Organize API endpoints, methods, and data flows based on their functionality. This organization will help you create test scenarios more efficiently.
3. Define Parameters
Identify and define the required parameters for each endpoint, including inputs, headers, authentication methods, and query parameters.
4. Familiarize Yourself with Request Tools
Learn how to send requests to the API using tools like Postman or command-line tools, which will help you interact with the API during testing.
5. Create Test Cases
Develop test cases for each endpoint, covering valid and invalid inputs, boundary conditions, and edge cases. Clearly define the expected outcomes for each scenario.
6. Set validation checks/assertions
Set up assertions to validate API responses, ensuring you check status codes, data integrity, and whether the returned values match expected results.
7. Execute Test Cases
Run your test cases systematically and compare the actual results with the expected ones to ensure all scenarios are addressed.
8. Document Failures
If a test case fails, document the failure in detail, including the test environment, input data, and any error messages to assist with troubleshooting. This structured approach ensures comprehensive testing and helps maintain the quality and reliability of the API.?
For API testing, you can utilize Postman. Postman is a widely used tool for API testing, offering a user-friendly interface that allows developers to easily create, test, and document APIs.
→ Related content: Test-Driven Development Tools
API Deployment
With testing complete and our API functioning as intended, you are now ready to move to the deployment phase. API deployment is the process of making an API available in a production environment, allowing end users or other systems to access it. This step involves moving the API from a development or testing environment to live servers, ensuring it performs correctly under real-world conditions.
You might wonder why Postman is not used for deployment. While Postman is a powerful tool for testing and documenting APIs, it does not directly handle deployment. Instead, after deploying your API to a server (like AWS, Heroku, or a personal server), Postman can be used to interact with and test the deployed API. By entering the API’s base URL in Postman and sending requests using methods like GET, POST, PUT, or DELETE, you can evaluate the responses, making Postman ideal for post-deployment validation and testing.
Many people choose AWS for deploying their apps because it simplifies the process compared to setting up and managing their own servers. AWS takes care of the infrastructure, allowing developers to focus on their applications.?
Create a Deployment via AWS CLI
Replace <your-api-id> with the actual API ID and <stage-name> with your chosen stage name (e.g., dev, prod).
Set Up the Stage: Go to the AWS Console’s Stages section to configure settings such as throttling, logging, and caching for each deployment.
bash
aws apigateway create-deployment \
--rest-api-id <your-api-id> \
--stage-name <stage-name> \
--description "Deployment description"
Conclusion
In this guide, we have covered all the key steps of API development, from design to deployment. Here’s a summary of the main points of this blog:
API testing is crucial for ensuring smooth communication between systems. Combining TDD with comprehensive testing strategies leads to reliable and secure APIs. With the right approach, your team can deliver high-performing APIs that meet user needs, scale effectively, and maintain top-quality standards.