7 Best Practices for Data-Driven API Testing

Gone are the days of manual testing, and in come the days of data-driven API testing. But what exactly does that mean? In short, it means utilizing large data sets to enhance and improve your API testing process.

You no longer have to enter data or rely on pre-defined parameters manually; instead, you can harness the power of real-world data to drive more comprehensive testing scenarios.

Not only does this save you time and effort, but it also allows for a more realistic and thorough approach to API testing. Preflight has prepared a list of 7 best practices for data-driven API testing, which will help you get started with this important testing methodology.

1. Know your endpoints and the data they return

Knowing what data your endpoints should return, you can easily identify anomalies or errors in the output. Understanding your endpoints allows for more efficient and targeted testing - rather than blindly throwing requests at an API and hoping for the best, you can specifically target the specific endpoints important to your application's functionality.

Utilizing this practice saves time and ensures that your API is performing as expected. That being said, it's important to note that endpoint-specific testing should not entirely replace more general or "black box" testing methods.

Testing a wide range of scenarios and inputs helps to anticipate unexpected issues and ensure robustness in your API. Overall, having a thorough understanding of your endpoints and their expected outputs is a key component of successful data-driven API testing.

2. Use a mocking library to mock out your dependencies

By using a mocking library while performing API tests, you can ensure that outside factors don't influence your test results. This is especially important for APIs that rely on external dependencies, like third-party databases or communication services.

By mocking out these dependencies, you can isolate and fine-tune specific areas of the API without worrying about outside variables throwing off your results.

Additionally, mocking libraries can also aid in creating test scenarios that may be difficult or impossible to create in real-life situations.

In short, including a mocking library in your API testing strategy can greatly improve the accuracy and efficiency of your tests. So next time you plan your data-driven testing process, consider adding a mocking library to the mix. Your tests will thank you for it.

3. Create comprehensive test cases for each endpoint

This means not just testing the response bodies but testing the headers and status codes as well. Another important aspect to consider is input validation – what happens if certain parameters are missing or invalid data inputted?

And don't forget about testing edge cases and unexpected errors. By thoroughly planning out and executing these test cases, you can ensure that your API can handle any data thrown at it.

Documenting your test cases allows for easy reference and makes it easier for others on the team to understand the scope of your testing efforts. Ultimately, comprehensive test case creation can go a long way in ensuring a successful and stable API.

4. Use data-driven testing to verify that your endpoints are returning the correct data

In API testing, data-driven testing can be incredibly valuable in ensuring your endpoints return the correct information. One best practice is keeping a separate data file, such as a JSON or CSV, that contains all the expected values for each endpoint you are testing. This allows you to easily update or add new test cases without updating your test scripts.

Another important aspect of data-driven testing is keeping your test scripts modular - writing them so that they can easily be reused for different endpoints and data sets. This not only saves time and effort but also helps to maintain consistency throughout your testing process.

And lastly, make sure to thoroughly validate the response data from your API calls before asserting it as "passed" - check not just for specific values but also data types and structures. By following these guidelines, you can leverage the power of data-driven testing to verify the integrity of your APIs.

5. Validate input and output parameters

This means ensuring that the data being passed into the API is in the correct format and within the expected range, as well as verifying that the output of the API matches what is expected.

Validating input data and output data helps catch any potential errors before they become more serious, such as affecting end-user experiences or causing data breaches.

Keeping track of inputs and outputs can help with performance testing, monitoring, and troubleshooting. In summary, consider validation regarding API testing - it's an important step for a smooth and successful application.

6. Test Positive & Negative Outcomes

Another key element to consider when testing your API is whether or not the data return values match what you expect under both positive and negative situations.

For example, you might set up a test scenario in which an endpoint returns no results if a request includes invalid parameters or where it returns incorrect information if certain types of test data are inputted.

At its core, this practice helps to ensure that your API will be reliable and stable even in difficult or unexpected situations. By testing positive and negative outcomes, you can rest easy knowing that your API is well-equipped to handle any scenario.

But remember to continually perform these tests throughout your API's lifetime - things can always change, and issues may arise that only become apparent over time.

7. Automate your tests as much as possible

We can save valuable time and resources by automating tests as much as possible and using data to drive those API automation testing processes. Not only does this increase efficiency and accuracy, but it also frees up room for more creative and strategic thinking. In addition, a data-driven approach allows for better tracking and analysis of API performance over time.

Here are the benefits of automated API testing:

Increased Efficiency

One of the primary benefits of automating data-driven API testing is increased efficiency. Automating data-driven API tests can save time by eliminating the need for manual testing. Additionally, automating data-driven automated tests can help to improve accuracy by ensuring that tests are run consistently and accurately.

Reduced Costs

Another benefit of automating data-driven API testing is reduced costs. Automating data-driven API tests can help to save money by eliminating the need for manual testing.

Improved Accuracy

Improving accuracy is another benefit of automating data-driven API testing. Automating data-driven API tests can improve accuracy by ensuring that tests run consistently. Automating data-driven API tests can help to eliminate errors that may occur during manual testing.

Increased Coverage

By automatically running all relevant application areas through a testing process, you can be sure that no part of the app goes untested leading to increased test coverage. This also helps to improve accuracy by making sure that each test case is executed the same way every time it runs.

Reduced Time To Market

Automating data-driven API testing not only eliminates the need for manual testing but also helps to reduce time to market. Furthermore, automating these tests improves accuracy by guaranteeing that all test cases are carried out correctly and consistently every time.

Improved Quality Of Results

Automating data-driven API tests can improve the quality of results by ensuring that all relevant application areas are tested. Automating data-driven API tests can help to ensure that all test cases are run consistently and accurately.

Automate your tests with Preflight

Preflight is a No-Code/Low-Code testing tool that helps Agile teams prevent flaky tests and work faster. With its powerful API testing, Preflight helps you automate your tests and increase their accuracy while decreasing the time and cost associated with manual testing.

Preflight's recorder is powerful, allowing you to recreate anything done on a web page practically. Automating your testing process from beginning to end is now easily attainable. With analytics and dashboards included, Preflight also makes it simple to monitor your API's performance over time while being able to identify any developing issues quickly.