Service Virtualization


Service virtualization refers to the process of simulating the behavior of APIs or components within an application under test. Services are often virtualized, that is, replicated or simulated as original services, to deliver the expected performance and output with the desired data inputs. Often developers and testers write the piece of code to imitate the behavior of a real service, which is expected to deliver the same outcome as that of the simulated system.

With the ever-increasing demand for faster and efficient deliverables to meet the market trends, the team of developers and testers resort to the best available mechanisms to accomplish software development activities within low budget and least dependency.

Implementing Service Virtualization 

Performing service virtualization demands establishing a connection between the application under test with the virtualized services to detect underlying components to deliver end-to-end test results. We attempt to list the following steps towards achieving service virtualization:

  • Capture - the virtualized service identifies the interactions between the application under test and the corresponding dependent systems. The purpose is to capture data, network packets, log files, and so on. 
  • Process - the next step is to process the network protocols and other data, captured by the virtual services and decoding it into its own way to replicate the same behavior to deliver the desired objective.
  • Model - the virtual services are finally put to use and integrated with the system under test (SUT) to create a similar environment as that of real services. 

Initially, the application to be tested and various other components are in isolation. Upon a release requirement, the services are identified, which are required to collaborate, and then necessary setup is created. 

For instance, an e-commerce application is being tested. It is required that the services, such as payment gateways, backend system, and similar other services are required to test the complete software package. Now the payment gateway might be a third-party service that has to be purchased or may be unavailable due to any reason. 

In such a situation developers or testers will write the code for implementing payment gateway services to simulate a real gateway and perform an end-to-end test to verify and validate the desired outcome.

Benefits of Service Virtualization

Service Virtualization can be beneficial in many ways. Some are listed as follows:

  • The time to gather and assimilate the third-party resources consume a lot of time, therefore writing optimized codes to execute such functionalities will reduce the time for release cycles.
  • Quick tests and builds are ensured with service virtualization, as teams can create virtual services and perform tests in parallel.
  • Tests can be performed even more rigorously with customized services, widening the scope for both positive and negative testing.
  • Cost is highly optimized, as service virtualization eliminates the need to look for options beyond the available environment.
  • The concept of virtualization to test an application widens the scope for early detection of defects, which can facilitate the right decision towards validating the functional requirements.

Tools for Service Virtualization 

Some of the popular tools available for service virtualization are as follows:

  • Traffic Parrot - The tool facilitates simulation of APIs and services to enable testing microservices without having much concern about the environment. Consumes less time and effort, which allows developers and testers to maximize productivity when working with cross-functional product teams, allowing faster release time. Offers support for HTTP, file transfers, IBM MQ, JMS among a wide range of other services.
  • UP9 - The tool offers the flexibility to automate test cases for microservices, Kubernetes, eliminating the need to constantly build and maintain tests, with the help of API. Enables early detection of regression tests so that maximum bugs can be avoided to reach the production stage. 
  • Wiremock - A simulator for HTTP-based APIs, which provides the provision to check edge cases and failure modes that may not be produced by a real API quite often. The tool supports record and playback and does not require the configuration of servers and SSL certificates.
  • Mountebank - The tool is an open-source platform that supports multi-protocol tests for any application. With this tool, developers and testers can perform tests for HTTP, TCS, SMTP protocols. This tool has the least constraints in terms of platform configuration and is frequently updated to ensure stability.
  • Hoverfly Cloud - This service virtualization tool offers great ease for conducting integration, automation, and performance tests. It can be easily configured on AWS, Google Cloud and can be scaled up according to a given set of requirements.
  • MicroFocus Data simulation software - The tool offers flexibility to modify data, network, and performance models, without updating test conditions and performance needs. It integrates service virtualization features like ALM, LoadRunner, Unified functional Testing which widens the scope for simulating any application behavior. Enables conducting scalable and secure tests with the least defects in the production environment.
  • CA Service Virtualization - This virtualization tool facilitates multiple developments and testing teams to work in sync. It provides mechanisms to test negative scenarios, performs stress tests, shift-left testing to increase testing speed by 20%-50%. 
    • MockLab - With a very friendly UI, it requires no code to configure simulations to completely automate tests. It enables checking for negative tests such as injecting delays, dropped connections, corrupt HTTP payloads, and so on. The tool saves much of the cost that is otherwise incurred on the adoption of third-party tools and also enables delivering more robust systems by simulating edge cases and faults. 
    • Rational test Virtualization Server - The tool facilitates continuous tests with the help of Integration Tester, in addition to early and frequent testing in the software development lifecycle. Few benefits of IBM rational tools are reduction in the cost of deployment and configuration, increased agility and flexibility, and great alacrity for aligning with business objectives to promote collaborative planning and testing.
  • Tricentis Tosca - Tricentis Orchestrated Service Virtualization helps to bring stability to the dependent systems to ensure reliable, complete, and continuous testing. Works best for systems that rely highly on interconnectedness to accomplish one objective.


Service Virtualization will benefit the developers and testers to overcome obstacles that often come across due to uncertainty associated with the unavailability of dependent components required to deliver any application. Organizations following DevOps culture can thus work seamlessly towards building a strong foundation towards continuous integration and delivery with the help of service virtualization.