@castore/lib-test-tools

Test tools

Test tooling for the Castore library.

📥 Installation

# npm
npm install --save-dev @castore/lib-test-tools

# yarn
yarn add --dev @castore/lib-test-tools

This package has @castore/core as peer dependency, so you will have to install it as well:

# npm
npm install @castore/core

# yarn
yarn add @castore/core

👩‍💻 Usage

MockEventStore

The mockEventStore util returns a copy of the provided EventStore connected to an InMemoryEventStorageAdapter, empty or with a given initial state. It follows the EventStore interface but adds a reset method to reset it to the provided initial state. The original event store is not muted.

import { EventStore } from '@castore/core';
import { mockEventStore } from '@castore/lib-test-tools';

const pokemonsEventStore = new EventStore({
  ...
});

const pokemonAppearCommand = new Command({
  ...
});

describe('My awesome test', () => {
  const mockedPokemonsEventStore = mockEventStore(pokemonsEventStore, [
    // 👇 Provide initial state (list of event details) in a type-safe way
    {
      aggregateId: '123',
      version: 1,
      type: 'POKEMON_APPEARED',
      ...
    },
  ]);

  beforeEach(() => {
    // 👇 Reset to initial state
    mockedPokemonsEventStore.reset();
  });

  it('pushes a POKEMON_APPEARED event', async () => {
    const { pokemonId } = await pokemonAppearCommand.handler({
      requiredEventsStores: [mockedPokemonsEventStore],
      ...
    });

    const { events } = await mockedPokemonsEventStore.getEvents(pokemonId);

    expect(events).toHaveLength(1);
  });
});

MuteEventStore

Unlike mockEventStore, the muteEventStore util mutes the original event store and replace its storage adapter with an InMemoryEventStorageAdapter matching the provided initial state.

import { EventStore } from '@castore/core';
import { muteEventStore } from '@castore/lib-test-tools';

const pokemonsEventStore = new EventStore({
  ...
});

const functionUsingTheEventStore = async () => {
  ...
};

describe('My awesome test', () => {
  muteEventStore(pokemonsEventStore, [
    // 👇 Provide initial state (list of event details) in a type-safe way
    {
      aggregateId: '123',
      version: 1,
      type: 'POKEMON_APPEARED',
      ...
    },
  ]);

  it('does something incredible', async () => {
    await functionUsingTheEventStore();

    // 👇 Use the original event store
    const { events } = await pokemonsEventStore.getEvents('123');

    expect(events).toHaveLength(1);
  });
});