Add test for using use_memo with use_effect

[pablosichert]

This PR is a reproduction test case for #2416.

Currently, when starting with (0, 0) and writing

Write(Some(0), None)
Write(None, Some(0))
Write(Some(0), Some(0))
Write(Some(1), None)
Write(None, Some(1))
Write(Some(1), Some(1))
Write(Some(2), Some(2))
Write(Some(0), Some(0))

this test results in the following reads:

Read(0, 0)
Read(1, 1)
Read(1, 1)
Read(0, 0)
Read(0, 0)

However, the expected result is

Read(0, 0)
Read(1, 0)
Read(1, 1)
Read(2, 2)
Read(0, 0)

[pablosichert]

Ok, interesting, if you change this line to:

Suggested change

	None
	rsx! {"{tuple:?}"}

The test passes.

[ealmloff]

The issue with memos over subscribing is fixed in #2506, but this test will still fail because it assumes that effects rerun once every time a dependency updates. They may drop updates freely as long as the latest value is consistent (in this test (0, 0)). I added a test to #2506 that tests for regressions in synchronous updates with memo