API Testing | Software Testing - Business Technology News

API testing is a sort of software testing that examines an application program interface (API) to ensure it provides the functionality, security, performance, and reliability required. The tests are run either directly on the API or as part of the integration testing process. In software, an API is a piece of middleware that lets two applications talk to one other. The code also describes how an application asks the operating system (OS) or other apps for services.

There are typically three levels to an application: the data layer, the service layer (the API layer), and the display layer (the UI layer). The API layer contains the application's business logic, which guides users on how to interact with the services, functions, and data stored within the app. API testing examines the business logic as well as the application and data replies' security. An API test often involves sending queries to API endpoints and comparing the outcomes against expectations.

API testing is commonly automated and utilized for continuous testing by DevOps, quality assurance (QA), and development teams.

How to Go About API Testing

An API testing process should start with a well defined program scope and a thorough grasp of how the API is expected to function. Some questions that testers should think about are:

What testing endpoints are available?
What are the anticipated response codes for successful requests?
What are the anticipated response codes for failed requests?
Which error message should be anticipated to display in the body of a failed request?

Once these criteria are known, testers may begin using various testing methodologies. API test cases should also be written. These test cases provide the circumstances or variables that testers may use to verify whether a certain system runs correctly and reacts appropriately. Once the test cases have been defined, testers may run them and compare the expected and actual outcomes. The test should examine replies such as:

reaction time, data quality, authorisation confirmation, HTTP status and error codes

API testing may examine a variety of endpoints such as online services, databases, and web user interfaces. Failures or unexpected inputs should be avoided by testers. The API should be protected against potential attacks and the response time should be acceptable.

To guarantee that the API can manage the expected user demand and function across many browsers and devices, tests should be built into the application itself.

The outcomes of nonfunctional testing, such as performance and security, should also be analyzed.

API testing types

API tests of many forms can be done to confirm that the application programming interface is functioning properly. They range from broad to specialized software assessments. Here are some instances of these tests.

Validation testing consists of a few simple queries that cover the entire product. The first round of inquiries is about the product: Was the right product created? Is the developed API the right product for the problem it's attempting to solve? Was there any significant code bloat (the creation of code that is needlessly large, sluggish, and inefficient) throughout development that might push the API in an unsustainable direction?

The following questions are about the API's behavior: Is the right data being accessed in the right way? Is there too much data access? Is the API appropriately storing the data given the precise integrity and confidentiality requirements of the data set?

The final set of questions focuses on the API's efficiency: Is this API the most efficient and correct way to do a task? Is it possible to change or delete any codebase in order to minimize impairments and enhance overall service?

Functional testing verifies that the API works as it should. This test examines various functions inside the codebase to ensure that the API operates within the anticipated parameters and can handle problems when the results are outside the specified parameters.

Load testing determines how many requests an API can handle. This test is frequently conducted after a single unit, or the entire codebase, has been completed in order to assess whether the theoretical answer can also function as a practical solution while operating under a specified load.

Reliability testing guarantees that the API produces consistent results and maintains a consistent connection between platforms.

In the larger security auditing process, security testing is typically lumped with penetration testing and fuzz testing Security testing includes both penetration and fuzz testing, but also attempts to check the API's encryption and access control techniques. Authorization tests for resource access and user rights management are included in security testing.

Security testing is the foundation for penetration testing. The API is assaulted in this test by someone with minimal knowledge of the API. This allows testers to examine the assault vector from a different angle. Penetration testing attacks might be confined to certain portions of the API or they can target the entire API.

Fuzz testing injects massive volumes of random data – also known as noise or fuzz – into the system in order to induce undesired behavior, such as a forced crash or overflow.

What is the significance of API testing?

User interface tests are frequently inefficient for evaluating API service functioning and frequently fail to cover all components of back-end testing. This might result in defects being left at the server or unit levels, which is an expensive mistake that can significantly delay product delivery and typically necessitates the rewriting of substantial sections of code.

API testing enables developers to begin testing early in the development cycle, before the user interface is complete. Any request that fails to provide the correct value at the server layer will not be displayed on the UI layer. This allows developers to fix at least half of existing defects before they cause major issues. It also allows testers to perform requests that would otherwise be unable to make through the UI, which is essential for exposing security problems.

Many businesses employ microservices for their software applications because they allow for more efficient software deployment. If one component of the program is being updated, the other portions can continue to work normally. Each application part has its own data storage and various instructions for dealing with it. Because the majority of microservices use APIs, API testing will become increasingly important as more businesses adopt the use of microservices.

API testing is especially essential in Agile software development, where rapid feedback is required for process flow. Unit and API tests are preferable over GUI tests in Agile setups due to their ease of maintenance and efficiency. If GUI tests are to keep up with the rapid changes in an Agile context, they frequently require extensive revamping.

Integrating API testing into the test-driven development process may assist engineering and development teams throughout the development lifecycle. These advantages are then passed on to clients in the form of better services and goods.

The Advantages of API Testing

API testing ensures platform connections are dependable, safe, and scalable. Among the specific advantages are:

Automation of API tests involves less code than automated GUI tests, resulting in faster testing and a reduced total cost.

API testing allows developers to access the program without a UI, allowing them to spot faults sooner in the development process. This also saves money since problems may be rectified more effectively when detected early.

Early detection of faults saves time and money.

API testing is independent of technology and language. JSON or XML is used to communicate data, which includes HTTP requests and answers.

When examining applications, API tests make advantage of severe situations and inputs. This eliminates vulnerabilities and protects the application against malicious code and brokenness.

API tests may coexist alongside GUI testing. For example, integration can allow new users to be created within the app prior to running a GUI test.

While API testing has several advantages, it also has drawbacks. The most typical API test limits are parameter selection, parameter combination, and call sequencing. Parameter selection needs validation of API request parameters, which might be problematic. However, testers must ensure that every parameter data fits the validation standards, such as using acceptable text or numerical data, having an assigned value range, and adhering to length constraints.

The combination of parameters might be difficult since each combination must be examined to see whether it contains difficulties connected to certain settings. Call sequencing is especially difficult since the system requires each call to occur in a precise sequence. This rapidly becomes difficult, particularly when working with multithreaded programs.

API testing software

When running an API test, developers may either design their own framework or utilize one of several ready-to-use API testing solutions. Creating an API test framework allows developers to tailor the test and not be constrained by a tool's plugins. Testers can include whatever library they think is acceptable for their chosen coding platform, create unique and simple reporting standards, and insert complex logic into the tests. If testers want to create their own framework, they'll require advanced coding expertise.

But API testing solutions have simple interfaces and require no coding, allowing less experienced developers to easily deploy tests. Unfortunately, techniques meant to examine broad API flaws can miss issues particular to the tester's API.

API testing tools are widely available, ranging from commercial subscription solutions to free source options. Examples of API testing tools include:

SoapUI. The tool is designed to verify API functioning in SOAP and REST APIs as well as web services.

JMeter by Apache. An open source load and functional API testing tool.
Apigee. Google's cloud API testing tool focuses on API performance testing.
You can rest assured. An open source, Java-specific language that facilitates and simplifies REST API testing.
Swagger user interface. An open source tool for creating a website that describes the APIs that are utilized.
Postman. A Chrome extension for confirming and automating API testing.
Katalon. An open source tool for UI automated testing.

An open source tool for UI automated testing.

API test examples

While the applications for API testing are limitless, here are two examples of tests that may be run to ensure that the API is giving the expected results.

When a user launches a social media app, such as Twitter or Instagram, he or she is prompted to log in. This may be done directly through the app, or via Google or Facebook, respectively. There is a possibility that the social media app has a deal with Google and Facebook to acquire some degree of user data. The social media app must next undergo an API test to guarantee that it can interact with Google and Facebook to pull the essential information that will enable the user access to the app utilizing login information from other sources.

Expedia and Kayak are two further examples of online travel agencies. When utilizing a trip booking system, users want all of the lowest flight alternatives for specified dates to be accessible and provided to them upon request. To locate the best flight alternatives, the app must interact with all airlines. APIs are used to do this. As a result, API tests must be done to guarantee that the travel booking system is effectively talking with other organizations and giving the proper results to users within the timeframe specified. Furthermore, if the user chooses to book a flight and pay with a third-party payment service, such as PayPal, API tests must be performed to ensure that the payment service and travel booking systems can effectively communicate, process the payment, and keep the user's sensitive data secure throughout the process.

API testing best practices

API testing recommended practices include the following:

When defining test scenarios, categorize them.
Include the chosen parameters in the test case.
To achieve comprehensive test coverage, create test cases for every possible API input combination.
To monitor the API throughout production, reuse and rerun test cases.
Use manual and automated testing to improve outcomes.
When testing the API, keep track of what works and what doesn't.
API load testing should be performed to assess the system's stress.
Failures in APIs should be tested. Tests should be repeated until they fail. The API should be evaluated to ensure that it consistently fails to find errors.
Call sequencing requires a strategy.
Prioritizing API function calls can make testing easier.
Use clear, easy-to-understand documentation and automate the process.
If feasible, keep each test case self-contained and isolated from dependencies.

Additional topics you might be interested in: