1. A method, comprising: receiving, by a processor, a test case for a project, via a test creation tool of a tool server, that specifies a Uniform Resource Locator and an authentication mechanism for an existing Representational State Transfer (REST) service, wherein the existing REST service is provided by a third party vendor; in response to the existing REST service being invoked, by the processor, capturing a request and response for the existing REST service; converting, by the processor, the test case into a test Representational State Transfer (REST) service for the project using the request and response and using the authentication mechanism, wherein the test REST service simulates the existing REST service, and wherein the test REST service is used for at least one of regression testing and performance testing; deploying and configuring, by the processor, the test REST service on different application servers; and testing, by the processor, features of a REST service client application on the tool server with the test REST service deployed and configured on the different application servers.