API (Application Programming Interface) is a computer interface that allows two different software systems to communicate and share data. A software system that performs an API contains numerous functions/subroutines that can be performed by another software system. Between two software systems, an API describes the types of requests that can be made, how they may be made, the data formats that may be utilized, and so on.
API testing is performed as part of integration testing to see whether they meet functionality, usability, efficiency, and security expectations. Developers used to use GUI-based testing to simplify their applications that interacted directly with their browsers in the past. API testing, on the other hand, has recently been deemed vital to the development process because it is quicker and more accurate than GUI-based tests. API testing enables the tester to identify bugs earlier in the development process, even before the user interface is developed. API testing also helps the tester to make requests that would otherwise be denied by the user interface. Since API does not have a GUI, which means that testing is done on the message layer.
Importance Of API Testing: API testing is all the more relevant as a result of its widespread use and integration in software development. API testing helps weed out crucial errors and defects in the API that could adversely impact the application’s performance and functionality. The errors could include security flaws, an inability to handle the wrong form of data input, or a large volume of load, among other things.
Automating API Testing: API automation will help you save time and money by speeding up your research. It is necessary to automate test cases that are performed repeatedly, such as regression cases, in all types of software testing. Similar to API testing, there may be some cases where you need to run code before each release, and those cases can be automated. API endpoints can also be used to store test data and execution history, making it easier to rerun tests.
Steps for Automating API Testing:
- Selecting the appropriate tool: On the internet, there are numerous API automation testing tools. The majority of them have identical features and a few extras to make your testing a little easier. Few tools are free to use, while others are only available for a fee. Before selecting any tool make sure it meets your testing criteria.
- Selecting the Method Type: We need to pick the method involved and enter the URL of your API. As this is a functional test, we need to make sure the API itself works. Look for the API runner function in your chosen tool, pick the method you want to evaluate, and enter the API’s URL.
- Adding information about API Requests: Any additional parameters, such as headers, a body, and so on, may appear to successfully run the request. Look for the parameters tab in the API runner window and then press the Add Parameter Test button, or the equivalent in your API automation tool, to add these parameters. After that, you’ll be given a field to enter the key and value of the parameters you want.
- Entering authentication credentials: If your hosted API needs authentication before you can use it to make a request, then you must start by entering the required credentials. Your API automation tool should have an Authorization tab with a drop-down list from which you can choose the type of authentication. This will supply you with the fields to input your username and password.
- Input Assertions: After that, you must include assertions in the test. You may use assertions to tell the API what kind of data or details it should return during the test. If the API fails to provide the type of response that the statement requires. There might be a possibility of the test failing. In the API Runner window of your tool, go to the Assertion tab. Additionally, choose the response and assertion condition from the drop-down menus. Further, in the Value field, enter the value. Simply click the Add Assertions button (or the equivalent in your automation tool) to add more assertions.
- Entering the Variables: Finally, using variables in the test allows you to store the values returned by the API in response to the test request. The values can be used as an expected assertion in future tests. This leads to a more functional testing experience. To add a variable:
- Go to the Variables tab in your automation tool
- Input the variable name and the JSON path the value
- Run the API Test: Now, It is time to run the API Tests. Have a check on everything before initiating the test. You should now be able to run the same test without again having to input the previous values. The proper output or result is now saved in the API’s Test Execution History.
- Repeating the Test process: Create new tests with your API testing tool and repeat them as required to obtain the desired results. When you’ve finished the last step, you’re ready to move on to the next step. Using an API testing tool, you’ve successfully automated a single API test case. You can now run tests with higher intensities and repetitions to fine-tune and polish your submission.
The business logic layer is represented by a collection of classes, functions, and procedures in the API. If an API is not thoroughly tested, it can trigger issues with both the API application and the calling application. It is considered a very important test in the software development field.