Test DOs in-process

Flare ships in-process helpers to exercise Durable Object routes without deploying to workerd. Import them from @flare-ts/core/cloudflare (the module needs a Workers environment: it imports cloudflare:workers at module scope). composeDurableInstance takes the built host.

composeDurableInstance

import {
  composeDurableInstance,
  DurableState,
  FlareDurableObject,
  makeEnv,
  makeFakeDurableState,
} from "@flare-ts/core/cloudflare";
import { FlareHost, FlareResponse, FlareService } from "@flare-ts/core";
import { cf } from "@flare-ts/core/cloudflare";

class Counter extends FlareService {
  public static override deps = [];
  #n = 0;
  bump() {
    this.#n += 1;
  }
}

class Room extends FlareDurableObject {
  public static override deps = [DurableState, Counter] as const;
}

const host = new FlareHost(cf);
host.scoped(Counter);
const room = host.durableObject(Room);

room.http.get(
  "/ping",
  { inject: { ds: DurableState } },
  (_ctx, scope) => new FlareResponse(200, { id: scope.ds.id.toString() }),
);

host.http.get("/_", () => new FlareResponse(200)); // Worker front door needs at least one route

host.build();

const inst = composeDurableInstance(
  host,
  makeFakeDurableState({ name: "room-1" }),
  makeEnv({ REGION: "enam" }),
  Room,
);

const res = await inst.fetch(new Request("https://do/ping"));
expect(res.status).toBe(200);

composeDurableInstance bypasses the real DO constructor (workerd owns that) and composes the per-instance container and DurableHandler you can drive with inst.fetch().

Resolve services

// The first argument is the DO class's `static deps` allow-list; Counter is
// listed in Room's `static deps` above.
const counter = inst.inject(Room.deps, Counter);
counter.bump();

Use this to unit-test services wired through the DO’s scoped container.

Fake storage

makeFakeDurableState accepts options including in-memory storage from makeFakeStorage():

const storage = makeFakeStorage();
const state = makeFakeDurableState({ name: "room-1", storage });

makeFakeStorage() covers only the KV subset (get, put, delete, list). No SQL: DOs that use state.storage.sql need a real cloudflare:test binding.

WebSocket routes

Drive WebSocket routes through inst.fetch() with an upgrade Request under the cloudflare:test pool: the upgrade allocates a WebSocketPair, a Workers-runtime global. res.webSocket on the 101 response is the client half of the pair. Use a real cloudflare:test binding when you need the real constructor, alarm, or RPC methods.

Related

• Testing overview: FLARE_MODE=test and app.test()
• Test WebSockets and DO: broader WS + DO testing
• Overview: registration model