leptos/leptos_reactive/tests/memo.rs

93 lines
2.6 KiB
Rust

#[cfg(not(feature = "stable"))]
use leptos_reactive::{create_memo, create_runtime, create_scope, create_signal};
#[cfg(not(feature = "stable"))]
#[test]
fn basic_memo() {
create_scope(create_runtime(), |cx| {
let a = create_memo(cx, |_| 5);
assert_eq!(a(), 5);
})
.dispose()
}
#[cfg(not(feature = "stable"))]
#[test]
fn memo_with_computed_value() {
create_scope(create_runtime(), |cx| {
let (a, set_a) = create_signal(cx, 0);
let (b, set_b) = create_signal(cx, 0);
let c = create_memo(cx, move |_| a() + b());
assert_eq!(c(), 0);
set_a(5);
assert_eq!(c(), 5);
set_b(1);
assert_eq!(c(), 6);
})
.dispose()
}
#[cfg(not(feature = "stable"))]
#[test]
fn nested_memos() {
create_scope(create_runtime(), |cx| {
let (a, set_a) = create_signal(cx, 0);
let (b, set_b) = create_signal(cx, 0);
let c = create_memo(cx, move |_| a() + b());
let d = create_memo(cx, move |_| c() * 2);
let e = create_memo(cx, move |_| d() + 1);
assert_eq!(d(), 0);
set_a(5);
assert_eq!(c(), 5);
assert_eq!(d(), 10);
assert_eq!(e(), 11);
set_b(1);
assert_eq!(c(), 6);
assert_eq!(d(), 12);
assert_eq!(e(), 13);
})
.dispose()
}
#[cfg(not(feature = "stable"))]
#[test]
fn memo_runs_only_when_inputs_change() {
use std::{cell::Cell, rc::Rc};
create_scope(create_runtime(), |cx| {
let call_count = Rc::new(Cell::new(0));
let (a, set_a) = create_signal(cx, 0);
let (b, _) = create_signal(cx, 0);
let (c, _) = create_signal(cx, 0);
// pretend that this is some kind of expensive computation and we need to access its its value often
// we could do this with a derived signal, but that would re-run the computation
// memos should only run when their inputs actually change: this is the only point
let c = create_memo(cx, {
let call_count = call_count.clone();
move |_| {
call_count.set(call_count.get() + 1);
a() + b() + c()
}
});
assert_eq!(call_count.get(), 1);
// here we access the value a bunch of times
assert_eq!(c(), 0);
assert_eq!(c(), 0);
assert_eq!(c(), 0);
assert_eq!(c(), 0);
assert_eq!(c(), 0);
// we've still only called the memo calculation once
assert_eq!(call_count.get(), 1);
// and we only call it again when an input changes
set_a(1);
assert_eq!(c(), 1);
assert_eq!(call_count.get(), 2);
})
.dispose()
}