Service Virtualization simulates the behavior of dependent components to provide an "always-on" test environment that allows DevTest teams to test earlier, faster and more completely. It is often used when dependent components connected to the AUT (e.g., APIs, 3rd-party services, databases, applications, and other endpoints) are not readily available for development and test.
The combination of Microsoft Azure, Microsoft VSTS, and Parasoft Service Virtualization provides a complete test environment for testing continuously-evolving, distributed systems. Unlike mocks, stubs, or simplistic API simulation, Parasoft Service Virtualization is environment-based. You can use automation to instantly provision complete test environments, as well as centrally reconfigure the performance, data, and behavior characteristics of all the environment's virtual assets for different test scenarios and for different stages of the delivery pipeline.
The complementary Parasoft Service Virtualization extension for Visual Studio contains a build task for deploying a complete, simulated test environment and another task for destroying the environment.