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5 Common Mistakes To Avoid When Using REST Assured For API Testing

Updated: Jan 24

REST Assured is a Java library that provides a domain-specific language (DSL) for writing authoritative, maintainable tests for RESTful APIs. It’s an easy language designed for developers to automate API testing by allowing them to specify the expected behavior of the API clearly and concisely.

REST Assured is widely used for automating API testing in the Java ecosystem and is a popular choice among developers due to its simplicity and ease of use. Let me make the long story shorter. In this article, I'll outline five common pitfalls you should avoid while using REST Assured to test APIs and discuss why this tool is so well-liked.


While API testing, live and learn 

As a powerful and popular tool for testing APIs, REST Assured is widely used by developers to ensure that their APIs are working correctly. However, it is easy to make mistakes when using REST Assured, which can lead to unreliable or incorrect tests. Here are five common mistakes to avoid when using REST Assured for API testing:


Not setting up the test environment correctly

To get reliable test results, it is necessary to set up the test environment correctly. This entails checking that the API server is operational and that all required dependencies are available. Failing to do this can lead to test failures or incorrect results.


Not specifying the correct HTTP method

REST Assured enables developers to specify the HTTP method that should be used for a request such as GET, POST, PUT, PATCH or DELETE. It is important to specify the correct method for each request, as using the wrong method can result in incorrect test results. 

Not handling errors correctly

APIs can return a variety of error codes and messages in response to invalid or unexpected requests. It is important to handle these errors correctly in the REST Assured test, as ignoring them can lead to false positives such as tests that pass when they should fail.


Not cleaning up after tests

It is good practice to clean up after tests by resetting any data that was modified during the test. Failing to do this can lead to test interference. Where the results of one test are affected by the state of the system from a previous test. 


Not using appropriate assertions

REST Assured provided a range of assertions that can be used to verify the behavior of an API. It is important to use the right assertions for the job, as using the wrong assertion can lead to incorrect test results.


By avoiding these common mistakes, you can ensure that their REST Assured tests are reliable and effective at detecting issues with their APIs.

Benefits of using REST Assured in API Testing

Here are some of the benefits of using REST Assured while API testing:

  • Easy to use: REST Assured gives a simple, concise DSL that enables you to specify the expected behavior of an API in a clear and readable way.

  • Supports a wide range of HTTP methods: REST Assured can be used to test APIs that use any HTTP methods, including POST, GET, PUT, DELETE, PATCH, and many more.

  • Controls complex request and response payloads: REST Assured can be used to test APIs that uses complex request and response payloads such as JSON and XML. It has built-in support for parsing and serializing these payloads, making it easy to work with them in tests.

  • Applied to a range of testing frameworks: REST Assured can be used with any testing framework that supports Java, such as JUnit, TestNG, or Spock.

  • It has excellent documentation and a large user community: REST Assured has excellent documentation and a large user community, which makes it easy to find help and resources when you need them.

  • Code Reusability: REST-assured is a Java client, so code reusability is possible. However, it can't be done in Postman.

  • Designing a Data-Driven framework: You are only able to provide one data file per collection to the Postman automation runner. REST-assured, however, has no such limitation.

Overall, it is an easy-to-use tool for testing APIs, and it is a good choice for many developers due to its simplicity, flexibility, and wide range of features.


In conclusion, REST Assured is a useful and popular tool for testing APIs, but it is important to use it correctly to get reliable test results. By avoiding the above-mentioned mistakes, you can ensure that your REST Assured test is effective at detecting issues with APIs. By following these best practices, you can have confidence in the reliability and correctness of API tests, which can help you deliver high-quality software to your user.

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