architecturekit 0.24.1

Building blocks for DDD-based applications with CQRS and event sourcing, on top of the EventSourcingDB by the native web.
Documentation 
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// The tests of the store check the state cache through load and execute.
// These tests check what those can not show reliably: which of two states of
// the same subject the cache keeps, and which subject it evicts.

use super::StateCache;
use crate::{Revision, Subject};

#[derive(Clone, Debug, PartialEq)]
struct Count(u32);

#[derive(Clone, Debug, PartialEq)]
struct Sum(u32);

#[test]
fn holds_nothing_for_a_subject_it_was_not_given() {
    let cache = StateCache::new(10);

    assert_eq!(cache.get::<Count>(&Subject::new("/books/42")), None);
}

#[test]
fn hands_out_a_state_with_the_id_of_the_last_event_it_was_built_from() {
    let cache = StateCache::new(10);

    cache.put(&Subject::new("/books/42"), Count(2), Revision::from(7));

    assert_eq!(
        cache.get::<Count>(&Subject::new("/books/42")),
        Some((Count(2), Revision::from(7)))
    );
}

#[test]
fn keeps_states_of_different_types_on_the_same_subject_apart() {
    let cache = StateCache::new(10);

    cache.put(&Subject::new("/books/42"), Count(2), Revision::from(7));
    cache.put(&Subject::new("/books/42"), Sum(9), Revision::from(7));

    assert_eq!(
        cache.get::<Count>(&Subject::new("/books/42")),
        Some((Count(2), Revision::from(7)))
    );
    assert_eq!(
        cache.get::<Sum>(&Subject::new("/books/42")),
        Some((Sum(9), Revision::from(7)))
    );
}

#[test]
fn keeps_the_state_built_from_the_later_event() {
    let cache = StateCache::new(10);

    // Two commands on the same subject may finish in any order, and the one
    // that read less must not replace the one that read more. The IDs are
    // compared as numbers, so 10 is later than 9.
    cache.put(&Subject::new("/books/42"), Count(10), Revision::from(10));
    cache.put(&Subject::new("/books/42"), Count(9), Revision::from(9));
    assert_eq!(
        cache.get::<Count>(&Subject::new("/books/42")),
        Some((Count(10), Revision::from(10)))
    );

    cache.put(&Subject::new("/books/42"), Count(11), Revision::from(10));
    assert_eq!(
        cache.get::<Count>(&Subject::new("/books/42")),
        Some((Count(11), Revision::from(10))),
        "a state built from the same event replaces the cached one"
    );

    cache.put(&Subject::new("/books/42"), Count(12), Revision::from(12));
    assert_eq!(
        cache.get::<Count>(&Subject::new("/books/42")),
        Some((Count(12), Revision::from(12)))
    );
}

#[test]
fn evicts_the_subject_used_least_recently() {
    let cache = StateCache::new(2);

    cache.put(&Subject::new("/books/1"), Count(1), Revision::from(1));
    cache.put(&Subject::new("/books/2"), Count(2), Revision::from(2));
    let _ = cache.get::<Count>(&Subject::new("/books/1"));
    cache.put(&Subject::new("/books/3"), Count(3), Revision::from(3));

    assert!(
        cache.get::<Count>(&Subject::new("/books/1")).is_some(),
        "it was used last"
    );
    assert_eq!(
        cache.get::<Count>(&Subject::new("/books/2")),
        None,
        "it was used least recently"
    );
    assert!(cache.get::<Count>(&Subject::new("/books/3")).is_some());
}

#[test]
fn counts_a_subject_that_is_given_again_once() {
    let cache = StateCache::new(2);

    cache.put(&Subject::new("/books/1"), Count(1), Revision::from(1));
    cache.put(&Subject::new("/books/2"), Count(2), Revision::from(2));
    cache.put(&Subject::new("/books/1"), Count(3), Revision::from(3));
    cache.put(&Subject::new("/books/2"), Count(4), Revision::from(4));

    assert_eq!(
        cache.get::<Count>(&Subject::new("/books/1")),
        Some((Count(3), Revision::from(3)))
    );
    assert_eq!(
        cache.get::<Count>(&Subject::new("/books/2")),
        Some((Count(4), Revision::from(4)))
    );
}

#[test]
fn counts_a_state_of_another_type_as_another_subject() {
    let cache = StateCache::new(1);

    cache.put(&Subject::new("/books/42"), Count(2), Revision::from(7));
    cache.put(&Subject::new("/books/42"), Sum(9), Revision::from(7));

    assert_eq!(cache.get::<Count>(&Subject::new("/books/42")), None);
    assert_eq!(
        cache.get::<Sum>(&Subject::new("/books/42")),
        Some((Sum(9), Revision::from(7)))
    );
}