Add a note to the documentation on testing controllers

[Ryan-Gordon]

As an exegesis user
I want a way to test my controllers
so that I can also test certain parts of the context (does the controller set the correct status code for example)

given an exegesis controller

when my controller modifies the status code

then I should be able to asset this change with access to the context object

given an exegesis controller

when my controller returns a result to the user
then I should be able review the returned payload to ensure it conforms to specs

I could try to implement this but wondering where to start.

[jwalton]

The way I've been doing this so far is to spin up an HTTP server and test things "full stack":

https://github.com/exegesis-js/exegesis-express/blob/0bd80261e830d194c59ad6d758d3688de7b9d104/test/integrationTest.ts#L55-L69

That's maybe not the most "unit test" way to do this, though. It does have some upsides, in that you can get the full schema validation on all input parameters and on the result.

If you want something a little more "focused", maybe a function that lets you provide a controller, input parameters, and a body, and runs it and returns back the result? You could generate a dummy "TestContext" object and pass it through. It would be very nice to keep response validation here somehow, but you'd need the full OpenAPI document and either a reference to the path or a reference to the schema you expect the return type to be.