hyper-stub is a Rust library that provides functions to create hyper clients that convert requests to responses using predefined functions, without doing any actual networking. This means the entire request/response lifecycle happens in a single process, and should have performance and stability improvements over, for example, binding to a port. One potential use case for this is stubbing HTTP interactions in tests to avoid slow/flakey/absent internet connections.
For API reference and usage examples, see the documentation.