In memory

Domain.InMemory runs your whole model in the current process: aggregates, views and policies, with nothing to deploy. Swap it for DomainCloudflare.DurableObjects and nothing else changes.

Host the model in memory

import * as Domain from "alchemy/Domain";
import * as Layer from "effect/Layer";
import { Bank, BankHandlers } from "@bank/domain/Bank.model";
import { MemoryLedgerStore } from "@bank/domain/Ledger/LedgerStore";
import { SiftFraudCheck } from "../src/Fraud/SiftFraudCheck.ts";
import { MfaChallengeLive } from "../src/MfaChallenge.ts";
import { SessionLive } from "../src/Session.ts";
import { StripePayments } from "../src/Settlement/StripePayments.ts";

// The model, its external systems, and the middleware its Apis declare: what a Worker would serve.
export const BankInMemory = Layer.mergeAll(SessionLive, MfaChallengeLive).pipe(
  Layer.provideMerge(Bank.layer(BankHandlers)),
  Layer.provide(Layer.mergeAll(Domain.InMemory, SiftFraudCheck, StripePayments, MemoryLedgerStore)),
);

Policies and projections run for real, and views catch up just after each command, as they do on Cloudflare.

Call it through an Api

testClient calls an Api in the same process, through its real middleware. Provide the in-memory model, and sign in with sessionClient.

import { expect, it } from "@effect/vitest";
import * as Effect from "effect/Effect";
import { CustomerApi } from "@bank/domain/CustomerApi.api";
import { sessionClient } from "@bank/domain/Session.middleware";
import { BankInMemory } from "./bankInMemory.ts";
import { register } from "./flows.ts";

it.live("a customer registers and deposits", () =>
  Effect.gen(function* () {
    const sam = yield* CustomerApi.testClient.pipe(Effect.provide(sessionClient("customer:c-1")));
    const accountId = yield* register(sam, "c-1", "sam");
    const { reply } = yield* sam.DepositMoney({ target: accountId, amount: 100 });
    expect(reply.balance).toBe(100);
  }).pipe(Effect.scoped, Effect.provide(BankInMemory)),
);

Each test that provides BankInMemory gets a fresh, empty bank.

Keep stories separate

Stories run on their own in-memory model with a controlled clock and scripted external systems, so you don’t provide Domain.InMemory to them. See Story.