In the context of Software-Engineering<\/a>, API-Stubs<\/a> are minimal implementations of an Application-Programming-Interface<\/a> used to simulate the behavior of a real component. They are primarily utilized during Software-Testing<\/a> to provide canned responses to method calls, allowing developers to isolate the System-Under-Test<\/a> from its dependencies. This is a fundamental practice in Unit-Testing<\/a> and Integration-Testing<\/a>.<\/p> A Stub<\/a> acts as a placeholder for a complex or unavailable module. For example, in a Microservices-Architecture<\/a>, if one service depends on another that is currently under development, the team can use Service-Virtualization<\/a> to create a stub that mimics the required interface. This enables parallel development and reduces bottlenecks. Unlike Mock-Objects<\/a>, which focus on verifying interactions and behavior, stubs are generally used to provide the state necessary for the test to proceed.<\/p> According to Martin Fowler's analysis of Mocks and Stubs<\/a>, stubs provide predefined answers to calls made during the test, usually not responding at all to anything outside what's programmed for the test.<\/p> In Remote-Procedure-Call<\/a> (RPC) frameworks such as gRPC<\/a> or Java-RMI<\/a>, a stub is a client-side proxy that facilitates communication with a remote Server<\/a>. The stub handles the Marshalling<\/a> of parameters and the Network-Communication<\/a>, making the remote call appear as a local function call to the Client<\/a> application. More information on the technical implementation of test doubles can be found on the Wikipedia page for Test Stubs<\/a>.<\/p>The Role of Stubs in Development<\/h2>
Stubs in Distributed Systems<\/h2>