API testing is done to verify the functionality, reliability and performance of an API. It must be done to confirm that all API endpoints and configurations are functioning properly.

There are several methods for testing an API, like using API testing tools, frameworks or manual ways. All these are part of an API testing process, and this guide will walk you through how to test an API through an automated testing framework.

6 Steps for Testing an API

A general process for QA API testing involves some simple steps and it’s easier through a testing framework. A test automation framework speeds up the API validation process test results across all environments stay consistent and repeatable.

Let’s see how you can do that by following this API testing process:

Select an API Testing Framework

An API testing framework is a collection of tools and libraries integrated with best practices to design and execute API testing with automated methods. It gives you a structure to send requests, validate responses, handle authentication, manage test data, and generate reports.

So, if you want to make API testing faster and more reliable without disrupting your CI/CD pipelines, your API testing framework must be right. Choose a framework that supports the API protocol you’re testing (REST, SOAP, GraphQL, etc.) and integrates with your development stack.

You can start from these popular test automation frameworks and choose the one depending on your project needs:

Note: If you need to test complex workflows and integrate with version control, select frameworks that support scripting and environment variable management.

Review the API Documentation

Now that you have selected an API testing framework, you have to start understanding these things:

Endpoints and request methods tell you what functions are available and how to call them (e.g., GET vs. POST changes the behavior).
Authentication requirements ensure you test with the correct security setup, preventing false failures.
Rate limits help you avoid hitting throttling errors during automated runs.
Expected response formats let you validate that the API returns the right data structure and content.

You need to review all these details because they define how the API is supposed to work. Without that understanding, you can’t create accurate or meaningful tests. Also, missing or unclear documentation can result in incomplete tests, so clarify any gaps before moving forward.

Since doing all this manually will take up lots of time, you can use documentation tools. For example, Swagger makes it easier to understand the request/response structure and identify possible edge cases.

Design API Test Cases

After getting a thorough understanding of the APIs, you can move on to building test cases with your test automation framework. First, you will define your test scenarios based on business requirements and expected functionality.

They can be as per these common categories:

Positive Tests: Validate correct responses with valid inputs.
Negative Tests: Check how the API handles invalid inputs, missing parameters, or unauthorized requests.
Boundary Tests: Push data limits to verify stability.
Performance Tests: Measure latency and throughput under load.

Assertions tell you if the API is behaving correctly. Without them, your test might send a request and get some response, but you’d have no automated way to verify. That’s why we use assertions to compare actual responses against expected values, such as status codes, headers, body content, and schema validation.

Learn more about what type of API assertions you get in vStellar Framework.

Execute API Test Cases

Next step is simple now because you just have to use your chosen framework to run the tests either locally or in a test environment. Automated execution will ensure that each endpoint is tested consistently.

Your test automation framework will provide functionalities to test with no code or low code testing, so you wouldn’t have to write and run each test case manually. Also with a framework that supports reporting, you can track not just pass/fail results but also response times, payload accuracy, and error messages for deeper insights.

💡vStellar’s low code testing features automate API testing with natural language to write test cases and multi-environment support.

Analyze Test Results

Review your test reports to identify patterns and issues. Modern frameworks provide HTML or dashboard-based reports which show failed cases, performance bottlenecks, and historical trends. Address any deviations quickly to prevent defects from moving downstream.

Commonly tracked API testing metrics: success rate, average response time, error rate, and failed assertion details.

Integrate With Your CI/CD Pipelines

Automated API tests are most effective when triggered during every build or deployment. You can use tools like Jenkins, GitHub Actions, GitLab CI, or Azure DevOps to run tests after code changes.

If a test fails, the pipeline should stop deployment, so that only stable code reaches production. This way, your API quality is validated continuously, catching issues early and reducing production incidents.

Example of QA API Testing with vStellar Framework

Let’s see how to test APIs practically through a test automation framework by using vStellar Framework as our example:

Prerequisites

Before installing vStellar Test, ensure you have:

JDK (latest version) required for the Java-based framework.
Apache Maven for dependency management and builds.
Git for version control and repository cloning.
IDE IntelliJ IDEA (recommended) or Eclipse/VS Code.
Compatible System with at least 4 GB RAM and sufficient disk space.

To download and install vStellar, just go to our website and Sign up for using the free version. From there you can download vStellar on Windows or Mac.

For more depth on each step of setting up vStellar read our detailed documentation.

Creating API Test Cases

To create API test cases in vStellar, follow these simple steps:

1. Feature File: Write tests in Gherkin syntax (Given, When, Then) with IntelliSense assistance.

feature file.svg

2. Excel (apiData): Store request details like body, headers, params, authorization, cookies.

1 (1).svg

3. Config.json: Define base URIs and active environments.

1 (4).svg

4. serviceEndpoints.json: Map endpoint names to paths for cleaner maintenance.

service endpoints.svg

5. Runner Class (API.java): Execute tests via IntelliJ run options or Maven.

runner file.svg

Why vStellar? It gives a modular approach, so maintaining test cases with it is easy. vStellar also supports REST/SOAP/GraphQL APIs, and integrates simply into CI/CD pipelines for continuous validation.

In case you face any trouble in this process, you’re welcome to contact vStellar’s Team to take up your queries.

Conclusion: Automate Your API Testing Process

This guide walked you through how to test API using an automated testing framework. We have covered the full API testing process from selecting the right framework, reviewing documentation, and designing test cases, to executing, analyzing results, and integrating into CI/CD pipelines.

With this API testing strategy, you can automate validation and catch issues early in the QA lifeycle. It will also keep your APIs deployment-ready. And test automation frameworks will take the burden off manual API testing.

In search for an all in one automated testing solution for APIs?

vStellar delivers a low-code API testing framework that streamlines every stage of QA automation. You can define and run API tests using Gherkin-style Feature files, requiring minimal scripting effort. It supports all major API types (REST, SOAP, and GraphQL) with full capabilities for sending requests and validating responses.

FAQs

Is API Testing Done Manually?

Yes, API testing can be done manually, but automation is preferred for speed and consistency.

How to Test If an API Is Working?

You can send requests using tools like Postman or cURL and check if the responses match expectations.

What Is REST API?

A REST API is an interface that lets systems communicate using HTTP methods like GET, POST, PUT, and DELETE.

What Are API Testing Tools?

API testing tools are software like vStellar, Postman, SoapUI, that help automate and validate API functionality.

How to Test API With An Automated Testing Framework?

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