async wasm tests don't seem to actually do anything

[carlsverre]

Describe the Bug

Currently the async tests in net use spawn_local, but don't actually wait for the spawned tasks to do anything. In addition, since spawn_local should always be run on the next microtask - the wasm instance will exit before any of the spawn_locals fire.

You can "test" this by adding an assert!(false) somewhere in the spawn_local part of the test.

Fix

To fix this, wasm_bindgen supports async tests: https://rustwasm.github.io/wasm-bindgen/wasm-bindgen-test/asynchronous-tests.html

I fixed the websocket test in a quick way here: master...carlsverre:gloo:feat-arraybuf

I tried a similar quickfix to the eventsource tests but discovered that the echo server in place is not handling cors - so that test is already broken. Unfortunately I don't have time right now to change the echo server / do more extensive work. Sorry about that.

[ranile]

Thanks for reporting! I would be happy to look at any PRs fixing the issue

[richardpringle]

@hamza1311, PTAL at #394