Add some unit tests

[user1823]

Covers most of the cases encountered in #3639

[user1823]

Not sure why is the test failing.

In the following test, the left side should produce 2 items. But CI failure shows 3 items on left side.

anki/rslib/src/scheduler/fsrs/params.rs

Lines 602 to 616 in f2463c5

	assert_eq!(
	convert(
	&[
	revlog(RevlogReviewKind::Review, 9),
	RevlogEntry {
	ease_factor: 0,
	..revlog(RevlogReviewKind::Manual, 7)
	},
	revlog(RevlogReviewKind::Review, 1),
	revlog(RevlogReviewKind::Relearning, 0),
	],
	false,
	),
	fsrs_items!([review(0), review(1)])
	);

[user1823]

@L-M-Sherlock, can you please have a look when you are free?

[L-M-Sherlock]

The output of CI showed that the test was failed:

--- STDERR:              anki scheduler::fsrs::params::tests::card_reset_drops_all_previous_history ---
--
  | thread 'scheduler::fsrs::params::tests::card_reset_drops_all_previous_history' panicked at rslib/src/scheduler/fsrs/params.rs:602:9:
  | assertion `left == right` failed
  | left: Some([FSRSItem { reviews: [FSRSReview { rating: 3, delta_t: 0 }] }, FSRSItem { reviews: [FSRSReview { rating: 3, delta_t: 0 }, FSRSReview { rating: 3, delta_t: 1 }] }])
  | right: Some([FSRSItem { reviews: [FSRSReview { rating: 3, delta_t: 0 }, FSRSReview { rating: 3, delta_t: 1 }] }])
  | note: run with `RUST_BACKTRACE=1` environment variable to display a backtrace

[user1823]

Thanks @L-M-Sherlock

[abdnh]

Just a naming nitpick:

Suggested change

	fn even_if_no_learning_steps_ignore_reviews_before_during_reviewing() {
	fn ignore_reviews_before_during_reviewing_even_if_no_learning_steps() {

[user1823]

Hope that you like the wording now.