Add unit test to check that AnyRequest handles missing parameters

[adamwulf]

First part of the issue:

Here's a unit test that shows part of the issue. When a new message comes in, the JSON is first decoded into an AnyRequest in Server's input stream handler, and then is decoded to the concrete Request type in TypedRequestHandler.

This means that the AnyRequest type must also be able to handle missing params.

These screenshots show the issue. First screenshot shows the list tools request arrive with {"method":"tools/list","jsonrpc":"2.0","id":1} trying to decode into an AnyRequest

second screenshot shows the decoding fail because M.Parameters.self is Value not Empty

Second part of the issue:

I believe this wouldn't fix it entirely, as the parameters from the AnyRequest are re-encoded and decoded in callAsFunction of the TypedRequestHandler. This decodes into M.Parameters.self directly, so the NotRequired handling in Request.init(from decoder:) doesn't get called here, and instead the decoding would fail immediately.

[mattt]

@adamwulf This is incredibly helpful. Thanks so much for taking the time to investigate and document everything.

I found a minimal change that gets your failing test to pass. Check this out —

extension Value: NotRequired {
    public init() {
        self = .null
    }
}

[mattt]

Alright, I'm going to merge this and cut a new release (0.5.1) now. Hopefully this gets everything sorted for you 🤞

[adamwulf]

phew - finally have time again to sit down and try this out - it works! 🎉 Huge thanks for your help and persistence on this 😄