Development teams have begun to rely more and more on APIs in order to cater to an increased demand for developing applications. API or Application Programming Interface consists of subroutines, protocols, functions and procedures as part of an underlying architecture that enables a developer to build software. This is similar to a GUI (Graphical User Interface) that helps a user to run an otherwise complex program. The underlying architecture hides complexities from the developer and instead presents objects, functions and actions in an easy to use form that are needed to build the application. APIs bring together disparate software systems by enabling communication and data exchange.
API represents the core architecture or business logic of software that helps integrate it with a third party application. Interestingly, users of any third party application interact with the application through a GUI, which in turn interacts with the API to get the desired outcome. Thus, API Testing assumes significance as it involves testing the integration of an end to end system.
In a business environment where agile methodologies, cloud computing and Internet of Things are becoming the buzzwords, API Testing helps in increased automation of the testing process. This has a bearing on lesser turnaround time for the software to hit the market. In API Testing standard modes of entering inputs like using a keyboard are skipped, and instead, automated calls from the software are made to register responses from the system.
Benefits of API Testing
- It enables increased synergy among multiple development teams.
- Component developers can validate system responses for error cases and address them.
- Verify functionality of components in different environments such as operating systems, hardware, third party applications, etc.
- Isolating components while testing can reduce dependence on preconditions, thus generating quicker outcome.
- Automates testing, so that behaviour of individual components can be controlled.
There are, however, a few challenges that can affect API Testing:
- If disparate components or dependencies present in the software are located remotely or owned externally by third party applications, mainframes or other services, their absence can seriously impair testing.
- If input to a component requires manual intervention, which is further dependent on constraints like distance or time zone, API Testing would take a hit.
- The dependencies might not be fully developed or available.
To address such issues, Service Virtualization comes into play. This technique simulates the behaviour of individual components that might be separated by distances or are just evolving. Through this technique, a virtual test environment is created whereby a request to the component is matched by a response. The type of response can be controlled by scripting the request.
According to Gartner, the need for API Testing and Service Virtualization has become significant for agile software development to meet newer paradigms like Internet of Things.
Five Benefits of Service Virtualization in API Testing are given below:
- To gauge erratic behaviour of an API: Often it is difficult to gauge the response of an API when fed with erroneous inputs. Through Service Virtualization in API Testing scenarios like downtime, slow rate of functioning or erratic behaviour can be studied – in a neutral setting.
- Reduce redundancies: API Testing can reduce redundancies and facilitate seamless end-to-end system integration.
- Cost saving: As dependence on external components reduces, a virtualized API shall lead to savings, which otherwise would have gone to maintain servers and bandwidths.
- Reduce turnaround time: Instead of waiting for actual APIs to be built, developers can make use of virtual APIs for faster time to market.
- Reusable: API virtualization not only simulates the core functionality of an application, but also generates error messages or awkward behaviour. As it can be easily configured whenever and wherever needed, it is practically reusable.