Test a pepys plug-in on Bun, with no host and no network.

The test store runs a plug-in's consumers over one in-memory database, with every table, the link table and the shared views, and answers the plug-in's queries. It repeats the host's link check and scope replace in TypeScript. It does not prove the scriptc compile or the Rust host.

Install

bun add -d @pepys/testing

Set the compiler options from the kit's README.

Then apply facts, and test a query on the rows that the plug-in's consumers write from them. A query test that seeds through the consumers fails when a consumer changes the shape of its rows:

import { expect, test } from 'bun:test';
import { createTestStore } from '@pepys/testing';
import { shelfPlugin, shelfSource, shelfTitleQuery } from './shelf-plugin.ts';

test('it answers a query from the row that a shelved fact gives', async () => {
  await using store = await createTestStore({ plugins: [shelfPlugin] });

  await store.apply(shelfSource, [
    {
      type: 'shelf.book.shelved',
      event: 'evt-1',
      entity: 'shelf:book:atlas',
      at: '2026-11-01T08:00:00.000Z',
      payload: { title: 'The Coral Atlas' },
    },
  ]);

  const answer = await store.query(shelfTitleQuery, { id: 'shelf:book:atlas' });

  expect(answer).toStrictEqual({ title: 'The Coral Atlas' });
});

bun test

Features

• createTestStore: apply facts or write rows, then run a query, read rows and read links.
• applyFactLog: apply the facts that createIngest of @pepys/ingest stored in a memory fact log to a test store, in place of the host. A second call applies only the records the log stored after the first.
• applyInBothOrders: apply facts in two orders and compare the stores.
• The memory adapter of the store reader, for a test of a core query.

Documentation

The pepys docs hold the design of the test store.