feat: added Express request handler

[jimezesinachi]

SynthQL pull request template

Why

Adding an Express request handler to allow easier setup and usage in Express applications

What changed

A single handler function and unit tests

Important

Tests are still very rudimentary at this point. All commented code is failing tests that I'm working on, and is there intentionally, until final review is requested.

[fhur]

Tests are still very rudimentary at this point. All commented code is failing tests that I'm working on, and is there intentionally, until final review is requested.

I don't understand the reasoning for this @jimezesinachi. How else do you know if it's working properly?

[jimezesinachi]

Tests are still very rudimentary at this point. All commented code is failing tests that I'm working on, and is there intentionally, until final review is requested.

I don't understand the reasoning for this @jimezesinachi. How else do you know if it's working properly?

What I'm saying is, all the current tests work and pass, and any commented code is work in progress (and hence you don't need to point them out, similar to what I mentioned last week).

[fhur]

This test isn't really testing anything useful @jimezesinachi

A few of the important invariants you should be testing:

1. The response is always 1..n lines of JSON
2. when returnLastOnly the status code can vary depending on the response kind
3. There's really no need to mock: spin up an actual server using http.createServer
4. Tests for error cases i.e. when the query is malformed
5. Add also tests using the react client. Notice that there is already a http.createServer in /react, instead of the custom handler code refactor to use the createExpressSynthqlHandler

[fhur]

don't do as Type, this is generally unsafe behaviour. Instead do

 const newReq: Type = { ... }

[jimezesinachi]

This would be ideal, but the goal here is actually type casting. We don't have all the values for the type, so using a type annotation in this case, causes a type mismatch error.