Testing

Tests build entities without a repository through es_entity::testing, enabled by the testing feature. Enable it from [dev-dependencies] only, so production builds do not contain it:

[dev-dependencies]
es-entity = { version = "...", features = ["testing"] }

use es_entity::testing::*; brings three functions onto every entity:

Each returns Result<User, EntityHydrationError> holding the entity a repository load would return: its events are all persisted, recorded at Clock::now(). Only the events a command pushes afterwards are new.

With the User from Entity Type and the NewUser from New Entity, the body of a #[test] in a #[cfg(test)] module reads:

extern crate es_entity;
extern crate sqlx;
extern crate serde;
use serde::{Deserialize, Serialize};
use es_entity::*;
es_entity::entity_id! { UserId }
#[derive(EsEvent, Debug, Serialize, Deserialize)]
#[serde(tag = "type", rename_all = "snake_case")]
#[es_event(id = "UserId")]
pub enum UserEvent {
    Initialized { id: UserId, name: String },
    NameUpdated { name: String },
}
pub struct NewUser { name: String }
impl IntoEvents<UserEvent> for NewUser {
    type IdSource = FromRepo;
    fn into_events(self, builder: EntityEventsBuilder<UserEvent, FromRepo>) -> EntityEvents<UserEvent> {
        let id = builder.id();
        builder.initial_events([UserEvent::Initialized { id, name: self.name }])
    }
}
#[derive(EsEntity)]
pub struct User {
    pub id: UserId,
    pub name: String,
    events: EntityEvents<UserEvent>,
}
impl User {
    pub fn update_name(&mut self, new_name: impl Into<String>) -> Idempotent<()> {
        let new_name = new_name.into();
        idempotency_guard!(
            self.events.iter_all().rev(),
            already_applied: UserEvent::NameUpdated { name } if name == &new_name,
            resets_on: UserEvent::NameUpdated { .. }
        );
        self.name = new_name.clone();
        self.events.push(UserEvent::NameUpdated { name: new_name });
        Idempotent::Executed(())
    }
}
impl TryFromEvents<UserEvent> for User {
    fn try_from_events(events: EntityEvents<UserEvent>) -> Result<Self, EntityHydrationError> {
        let mut hydrator = User::hydrator();
        for event in events.iter_all() {
            match event {
                UserEvent::Initialized { id, name } => {
                    hydrator.id(*id).name(name.clone());
                }
                UserEvent::NameUpdated { name } => {
                    hydrator.name(name.clone());
                }
            }
        }
        hydrator.build(events)
    }
}
use es_entity::testing::*;

fn main() {
let id = UserId::new();
// `NewUser`'s repo generates the id, so the test picks it.
let mut user = User::hydrate_from_new(id, NewUser { name: "Willson".to_string() }).unwrap();
// Any event stream can be hydrated directly too.
let same = User::hydrate_from_events(id, [UserEvent::Initialized { id, name: "Willson".to_string() }]).unwrap();
assert_eq!(user.name, same.name);
assert!(!user.events().any_new());

let new_name = "Gavin".to_string();
assert!(user.update_name(new_name.clone()).did_execute());
assert_eq!(user.name, new_name);
assert!(user.update_name(new_name).was_already_applied());
}