A Closer Look At API Testing As The Buzz Grows Around The API Enterprise

An introduction to APIs

As every programmer now knows, an Application Programming Interface (API) is a computing interface that allows data exchange and communication between two different software systems. An API defines how the two software systems can interact, the type of requests to be made, how to make the requests, data formats to be used, etc.

As enterprises become focused on integration and simplification of the enterprise tech ecosystem, APIs are back in focus as is their testing.

Enterprise API Testing

Examples of API use-cases that we use in our Daily Lives

From logging in to any social media platform to performing a simple google search, everyone has accessed API integration somewhere or the other. Enterprises are building an array of applications and solutions on such use-cases. For relatability, here are five common examples of API usage in our daily lives.

  • Login using XYZ account: It is very convenient to visit any new website and find the functionality to log in with Facebook, Google, GitHub, or other pre-existing accounts. This feature also relies upon APIs to not pose a security threat to your accounts. The applications with this feature simply rely upon APIs to authenticate the user with each login through identification information.
  • Weather snippets: Another common API usage is checking the weather data. Users simply look for weather + specific place, and the search result finds a dedicated box at the top (a rich snippet) with the weather forecast. Since Google does not collect weather data itself, this forecast is outsourced from a third party with the help of APIs. The weather APIs send them data that is easy to reformat. Currently, Google uses data from The Weather Channel.
  • Travel booking: It is easy to get flabbergasted by the deals and cheap flight options available on travel booking sites. But all this data is also extracted using third-party APIs to collect hotel and flight availability details from providers. APIs help machines automatically exchange data and requests, in the lack of which, the entire process of travel booking used to be manual.
  • FX brokerages and trading: Investments have grown in the digital world, and several applications have come up with APIs to help with trading. With access to multiple FX markets, APIs facilitate algo-trading strategies and allow access to live-streaming prices, trade execution, and advanced order types.
  • Pay with PayPal: PayPal or other payment merchants are directly embedded within eCommerce stores, nowadays. This functionality is also supported by APIs that ensure the end application only accesses the information that it requires and does not acquire unintended permissions. The API also comes into play to send confirmation of payment back to the application.
  • Bots: Social media bots are powered by APIs. Users can use these bots to send hourly reminders, identify grammatical errors, get tweets when Netflix releases new content, and also get reminders of new activity on their own Twitter accounts.

What is API Testing?

API testing is testing that validates the functionality of API. As the name suggests, API testing checks the overall functionality, performance, reliability, and security of the programming interfaces. API testing does not look at the overall appeal and presentation of the application like GUI testing. It focuses on the business logic strata of the software architecture and is often performed at the message layer.

Classes of Web API: SOAP and REST

There are two wide divisions of web service for Web API – SOAP and REST.

Simple Object Access Protocol (SOAP) is defined by the W3C standards, a standard protocol to send and receive web service responses and requests.

Representational State Transfer (REST), like HTTP, is a web standards-based architecture. There is no official standard for REST Web APIs.

API Testing Approach

API testing follows a predefined methodology, once the build is ready. This testing may not even require the source code. The following are tested in API testing:

  • Understand the functionality of an API.
  • Define the input parameters.
  • Verify how the error codes are handled by the API.
  • Keys verification.
  • Test case to perform XML, JSON schema validation.
  • Validate the keys with a range of minimum and maximum APIs.

Apart from the usual SDLC process of testing, API testing should also cover documentation, automated testing, security testing, usability testing, and discovery testing.

Bugs detected in API Testing

The common bugs detected during API testing are:

  • Security issues.
  • Missing or duplicate functionalities.
  • Performance discrepancy.
  • Incorrect handling of valid argument values.
  • Incorrect structuring of response data (JSON or XML).
  • Multi-threading issues.
  • Unused flags.
  • Failure in handling error conditions gracefully.
  • Failure in establishing a reliable connection with the API.
  • Improper errors.

Challenges of API Testing

The major challenges in API testing include:

  • Tracking API inventory and keeping up with the updates.
  • Thorough knowledge and understanding of business logic and rules.
  • Complex contracts or protocols for API interaction.
  • Testing enormous data and keeping it reusable.
  • Testers should have coding knowledge.
  • Testers should also know parameters selection and categorization.
  • Validation and verification of output in a different system.
  • No GUI available to test the application.
  • Parameter Combination, Parameter Selection, and Call Sequencing pose as main challenges in Web API testing.
  • Exception handling function should be tested.


The Solution to all These Problems:

APIs are everywhere in our daily digital lives. To succeed in the digital sphere, most organizations are now integrating APIs into their existing system strategies. However, appropriate API testing continues to be a challenge.

The ThinkSys API testing services stand apart as an integral part of API development and integration. Their reliable services guarantee the best security and compliance testing. From performance to functionality, they focus on every core aspect of an API and ensure maximum risk coverage to improve productivity.

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