Testing - Restate

The Typescript SDK has a companion library which makes it easy to test against a Restate container: @restatedev/restate-sdk-testcontainers. This uses Testcontainers to run a Restate Server in a Docker container and let you test your Restate handlers.

Setup

RestateTestEnvironment.start creates a Restate container and executes a user-provided closure to register services. An optional second argument allows you to specify a custom Testcontainer for Restate.

describe("ExampleObject", () => {
  // import { RestateTestEnvironment } from "@restatedev/restate-sdk-testcontainers";
  let restateTestEnvironment: RestateTestEnvironment;
  // import * as clients from "@restatedev/restate-sdk-clients";
  let restateIngress: clients.Ingress;

  beforeAll(async () => {
    restateTestEnvironment = await RestateTestEnvironment.start({
      services: [router],
    });
    restateIngress = clients.connect({ url: restateTestEnvironment.baseUrl() });
  }, 20_000);

  afterAll(async () => {
    if (restateTestEnvironment !== undefined) {
      await restateTestEnvironment.stop();
    }
  });

Calling services

The Restate ingress client can be used as usual (see the clients documentation)

it("Can call methods", async () => {
  const client = restateIngress.objectClient(router, "myKey");

  await client.greet("Test!");
});

Checking and mutating state

The stateOf method on the RestateTestEnvironment class can be used to obtain a handle on the Virtual Object / Workflow state for a particular key.

it("Can read state", async () => {
  const state = restateTestEnvironment.stateOf(router, "myKey");

  expect(await state.getAll()).toStrictEqual({});
  expect(await state.get("count")).toBeNull();
});

it("Can write state", async () => {
  const state = restateTestEnvironment.stateOf(router, "myKey");

  await state.setAll({
    count: 123,
  });
  await state.set("count", 321);
});

Typed state

stateOf can be provided with a type for the services state, to allow for type-safe state operations.

type ServiceState = { count: number };

it("Can operate on typed state", async () => {
  const state = restateTestEnvironment.stateOf<ServiceState>(router, "myKey");

  await state.setAll({ count: 1 });
  await state.set("count", 2);
});

Testing non-determinism bugs

Forces Restate to replay the handler on every suspension point. Use this to hunt non-determinism bugs. If your handler is not replay-safe, this will surface the issue:

describe("with alwaysReplay", () => {
  let env: RestateTestEnvironment;

  beforeAll(async () => {
    env = await RestateTestEnvironment.start({
      services: [router],
      alwaysReplay: true,
    });
  }, 20_000);

  afterAll(async () => env?.stop());

  it("replays after every suspension", async () => {
    // handler logic here
  });
});

Disabling retries

Disabling Restate’s built-in retry policy lets you surface failures immediately instead of hanging through retry backoff. Useful when testing error paths in your handlers:

describe("with disableRetries", () => {
  let env: RestateTestEnvironment;

  beforeAll(async () => {
    env = await RestateTestEnvironment.start({
      services: [router],
      disableRetries: true,
    });
  }, 20_000);

  afterAll(async () => env?.stop());

  it("fails immediately without retry backoff", async () => {
    // handler logic here
  });
});

​Setup

​Calling services

​Checking and mutating state

​Typed state

​Testing non-determinism bugs

​Disabling retries