pub constructor for tonic::transport::Error

[fridge-dev]

Feature Request

Motivation

We have code that calls Endpoint::connect() and handles the returned error. We want to write unit tests that exercise our error handling logic. Currently, we cannot create a tonic::transport::Error because all of the constructor methods are pub(crate), and so we can't test our error handling logic.

We have a workaround, where we create a thin wrapper around Endpoint::connect() that returns an Err variant like this:

enum TonicErrorWrapper {
    Real(tonic::transport::Error),
    Fake,
}

...and we only test with TonicErrorWrapper::Fake. We would like if tonic::transport::Error had a public constructor so we can test our error branches without introducing wrapper types.

Proposal

Make Error::new() or Error::from_source() public, instead of pub(crate). Or introduce some new constructors intended for public use.

I would even be fine with Error::dummy_instance_for_tests(). I just need an actual instance for my tests.

I am not sure what would be best for public API surface of this crate. I'll leave that up to hyper team.