How to Create an API Test Automation Strategy

Disruptions in the back-end exchange of data, files, and other information can wreak havoc without appropriate API testing. If these connections fail, the application also fails.

Develop an efficient suite of automated API tests to ensure an application functions as expected. API test automation is hard, but it’s easier and less error-prone than UI test automation or process test automation. Automated API test suites concentrate on the functionality of the API and require less overall test maintenance. With the appropriate tool and a supportive developer resource, QA can create automated API test suites effectively and efficiently.

Identify which API tests should be automated

A excellent candidate for an automated test suite is any API that requires continuous or frequent testing. Review the application’s functionality, all available workflows, and API documentation in order to determine which APIs require continuous testing.

The following are examples of API tests that necessitate continuous testing or monitoring:

  • Endpoint validation. Is it operable? Accepting only genuine messages?
  • Data validation. Displays the application the expected data? Is the data updated precisely after an application update?
  • API structure validation. Does the response contain the correct data type mapping, or does the correct data appear in the incorrect field?
  • Security measures. Does the token response and reception function as expected? What about the processing of rejected messages?
  • Communication failures. What occurs when a message or data transfer fails?
  • Validation of message format. Are messages meeting formatting standards?

APIs that are utilised infrequently may be prioritised at the end or tested manually using functional regression test suites already in place. APIs that provide news feeds or decorative elements in an application are essential, but they likely do not require continuous testing or test automation.

Testers must verify that data-related APIs across application platforms return the expected data. Most applications, for instance, support both web and mobile applications. Both application platforms are likely dependent on data from the same API connection, but are programmed independently. Create automated tests to verify that both display identical data.

Once teams have covered the API connection with fundamental tests, they can add complexity and increase test coverage. QA testers utilising Postman, for instance, can begin automating via a collection of JavaScript fragments independently or in combination to increase test coverage.

API test automation best practises

API test automation is useful for functional, connectivity, and security evaluations. It is crucial to ensure endpoints are not only responsive but also capable of processing valid and invalid messages. Security is essential to business operations, and it pertains to both the functionality and connectivity of applications. To maximise business value, develop API tests that encompass all three of these characteristics.

Develop a suite of automated API functional and security tests to run continuously or, at a minimum, daily. Add tests for connectivity in both expected and failure scenarios. Execute connectivity tests at least once per day or per week, depending on the API’s importance. 

Error messaging and failure tests let you know how an API handles poor data and alert you to any other problems within the application’s API set. It is preferable to discover system failures during testing rather than when consumers are using the system.

Choose an instrument for automated API testing

Numerous tools support API test automation. Consider a free trial or free version before committing to a tool to ensure that it is user-friendly and expandable enough to provide maximum API test coverage.

The majority of API testing tools provide code fragments and support custom coding. Teams are able to construct valid tests using a variety of coverage patterns using only the code snippets. In addition, the tests are always modifiable in order to add additional detail or expand coverage.

The following technologies enable the automation of API tests:

  • Postman. Contains both free and paid options. Helpful documentation and tutorials.
  • Katalon. Accessible to all expertise levels. Has minimal maintenance requirements and supports CI/CD and DevOps tool integrations.
  • Apigee. APIs are designed, secured, analysed, scaled, and tested. A component of the Google Cloud service.


SoapUI. Tool for evaluating both REST- and SOAP-based APIs.

JMeter. Java-based open source cross-platform testing framework. Apache JMeter operates on any platform with a Java virtual machine.

ReadyAPI. New product that offers the same essential features as SoapUI.

The aforementioned list is merely a sample; there are numerous instruments available.

Example of an API test automation strategy utilising Postman

Let’s discuss the initial Postman API request test creation and automation steps.

To begin, launch Postman, then create a workspace and a request. The request is a message sent to the tested API. In the following examples, we utilise Postman’s public API. To create a request, select the HTTP Request option in the upper-left corner of the screen. You will then see an Untitled Request tab at the top of the screen. This is a new request from you. You can add a title before selecting GET, POST, or PUT and entering the endpoint’s URL, parameters, authorization, headers, and payload.


View the request sample in Figure 3. The request pane displays the name; this example utilises the GET method and provides the URL of the endpoint to test. Observe that the Headers pane displays five headers. Postman generates these automatically for you.

When evaluating protected APIs, the Authorization and Params tabs display the username and password or authentication required to obtain a valid security token. The API password and security token are known by your API developer or IT manager.

Click Send once the request has been prepared for processing. The request name and request type are highlighted in the centre of the window in Figure 4. Once you click Send, the response body will appear in the lower portion of the window. The optimal view is JSON, with additional information to the right signifying whether the message was successfully processed — in this case, 200 OK.

We can then create test automation based on our request. Click the Tests tab on the same line as the Params and Authorization tabs. Utilise the available code samples on the right to develop automated API tests. When a request is sent, the automated tests execute and populate the Test Results pane with the results.

Figure 5 utilises two code fragments. We revised the initial submission, so it now passes. The second was left unchanged, so it fails. Always modify the snippet to reflect the response data being validated. When a request is sent, the test results are populated.

Next, add specificity to your automated API tests based on the API’s testing requirements. Modify the excerpts based on the API response data to validate data, fields, security tokens, and whether the message is processed successfully or not.


Read More: Digital Engineering Trends—What’s New?

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