API Testing — Everything You Want to Know

What is API testing — Check-check, one, two!

“API testing allows us to examine Application Programming Interface. This is necessary to maintain connection between your enterprise and your customers online by making it smooth, secure, fast, compatible, and enjoyable. API testing algorithm is pretty simple on its own, but it requires a considerable amount of knowledge, experience and competence”.

API stands for Application Programming Interface. In simple terms, it’s like a magic glue that keeps your online operations together, while providing a smooth customer experience. 

From the technical point of view, API is a channel, which guarantees an easy flow of data, requests, commands, and other details between two different software systems. For example System A can be your server, while System B is a client’s computer or phone. 

There’s a good deal of mystery surrounding API testing. In reality, it’s not that sophisticated. But the team tasked to perform it should have a rich skill set that includes knowledge of:

• Server architecture: HTTP and its alternatives, DNS.
• Data formats: JSON, YAML, RSS, Atom, XML, and others.
• Languages for automated testing: JavaScript, Ruby, Kotlin, Python, etc.
• Web service classes: Simple Object Access Protocol (SOAP) or Representational State Transfer (REST). 

All these tools and measures help to assess security and performance levels of your API, which plays the role of a mediator or middle man, if you please. Absence of a reliable API equals absence of sales, deals and clientele.

To perform the API’s health check, we need to employ various techniques. For example, it includes specifying API’s input and output status, attesting its smaller components like tokenization, selecting the best verification methodology, choosing an appropriate testing utility, and so forth.

There’s a cavalcade of effective test tools: Rest-assured, Assertible, Citrus Framework, Hoppscotch, and others. While these tools focus on the same problem, each one of them has a few unique and savvy features: transaction monitoring, codeless API test generation, Command-line support, SOC2 Type2 compliance, and other vital technicalities.

We at Kvan have developed a simple algorithm to get things going. It includes 3 steps:

1. Preparing the environment

   To make sure your API will work like a clock in the ‘combat conditions’, we prepare an environment that will simulate a real-life situation. This trick will help us expose potential weak points and vulnerabilities that may sabotage the website’s work during the customer inflow.

2. Sketching the test plan

   The testing process will be a victorious campaign with the right plan! We’ll select the appropriate testing types and scenarios, while also setting the time limits. Positive and negative test types are a must at this stage: they reveal functionality pitfalls, security breaches, performance hiccups, and so on.

3. Getting the right tools

   As we’ve mentioned, there’s a rich repertoire of test tools. But every service we test requires a unique approach. Therefore, we fetch the suitable tool to meet the specification of both our testing plan and your enterprise. This way, we achieve a nearly surgeon’s precision at removing potential flaws from your system.

What are API testing types — The lucky 7

“API testing usually includes 7 types: Security, Interface, Performance, Requirement, Backward Compatibility, Source Code, and Validation testing. They cover an extensive amount of potential issues and problems, which must be eliminated before your project goes live. Additional testing phases can be added at will”.

We at Kvan employ a testing matrix that helps us examine every aspect of your API. Canonically, about ⅕ of all testing time and effort should be dedicated to API — it’s a golden standard. 

So, we offer 7 main testing types:

1. Security 

   Security comes first. According to Forbes, in 2022 malicious actors can penetrate 93% of all companies operating online. Such a calamity can result in downtime, data loss, and irrecoverable reputation damages to your brand. 

   However, with proper API testing we can mitigate basically all existing attack types: Man-in-the-Middle, ransomware, phishing, Distributed Denial of Services (DDoS), and many others. 

   We’ll check the encryption validation, locate every breach possible, and fix all the ‘mole holes’ in the API’s security.

2. Interface

   Usually, API testing leaves the GUI out. However, we believe that for better performance testing accessibility of the GUI should also be checked. This will allow your clientele to enjoy a smooth and intuitive user experience.

3. Performance 

   Your website or mobile app can’t afford downtime. We know this and pay special attention to how the API will respond under the peak load. 

   For that, we can simulate a massive user influx, measure the API’s reaction, assess performance, and detect possible vulnerabilities that may cause a crash. This will help your system firmly stay on its feet when the client number spikes

4. Requirement 

   API’s requirement testing is a smart way to squash bugs early. The goal of this phase is to locate every possible inconsistency in the system, so later stages — like mobile app development — will be secured from potential bugs. This measure helps to provide maximum software quality.

5. Backward compatibility

   It’s essential to provide compatibility with the older versions of the API. This is crucial, as many of your customers may not update their operating systems or mobile apps just because they forget to. Backward compatibility will help you keep them by your side no matter whatever technical advances you can make. 

6. Source code

   Source code is the foundation of your online presence. To avoid cracks and crannies, we attest its performance with a set of input and conditional tests.

7. Validation

   To conclude the development cycle, we perform validation checks. They are necessary to make sure that the tested system strictly follows the set requirements, doing exactly what it is expected to do. This testing is being performed after all API components are fully verified.

We have listed the 7 primary steps of API testing. But more can be deployed if your project dictates so. For example, we can add mobile testing if you plan on integrating a mobile application, categorize API endpoints to make its structure more intuitive, perform negative/positive tests, and so on.

Negative tests imply that API’s behavior will be verified at different authorization levels, input validation tests will be carried out, and we’ll make sure that the API always responds with an adequate reaction.

Positive tests, meanwhile, help us use the lowest or highest amount of the required fields to specify input, ensure that the response status code behaves according to the requirements and check that API always receives input and responds with an appropriate output in return.