Database Testing with Poku and pg (PostgreSQL)

End-to-end example of testing a PostgreSQL database with Poku and the pg driver, from installing the driver to spinning the database up with Docker Compose.

Open the connection in an outer describe, put every assertion inside its own it, and close the connection at the end of that same describe, so cleanup always runs regardless of what an individual assertion does. The container lifecycle lives in a poku.config.js anonymous plugin that uses @pokujs/docker to run setup before the suite and teardown after it, so the suite runs with a plain npm test.

Install

npm i pg

npm i -D poku tsx @pokujs/docker @types/pg

Configure the credentials

.env.test:

DB_HOST=localhost
DB_PORT=5432
DB_USER=postgres
DB_PASSWORD=secret
DB_NAME=app

.gitignore:

.env.test

Start the database

docker-compose.yml reads the same .env.test to configure the container:

services:
  postgres:
    image: postgres:18
    environment:
      POSTGRES_USER: ${DB_USER}
      POSTGRES_PASSWORD: ${DB_PASSWORD}
      POSTGRES_DB: ${DB_NAME}
    ports:
      - '${DB_PORT}:5432'
    healthcheck:
      test: ['CMD-SHELL', 'pg_isready -U ${DB_USER} -d ${DB_NAME}']
      interval: 5s
      timeout: 5s
      retries: 10
      start_period: 30s

  db-ready:
    image: busybox
    command: ['tail', '-f', '/dev/null']
    depends_on:
      postgres:
        condition: service_healthy

Connect

db.ts reads every access from process.env:

import { Client } from 'pg';

export const connect = async () => {
  const client = new Client({
    host: process.env.DB_HOST,
    port: Number(process.env.DB_PORT),
    user: process.env.DB_USER,
    password: process.env.DB_PASSWORD,
    database: process.env.DB_NAME,
  });

  await client.connect();

  return client;
};

Write the test

users.test.ts:

import { describe, it, assert } from 'poku';
import { connect } from './db.js';

await describe('Users table', async () => {
  const client = await connect();

  await describe('Seed', async () => {
    await client.query(
      'CREATE TEMP TABLE users (id INT PRIMARY KEY, name TEXT)'
    );
    await client.query('INSERT INTO users (id, name) VALUES (1, $1)', ['Poku']);
  });

  await it('reads the inserted user', async () => {
    const result = await client.query<{ name: string }>(
      'SELECT name FROM users WHERE id = $1',
      [1]
    );

    assert.strictEqual(
      result.rows[0].name,
      'Poku',
      'The inserted user is returned'
    );
  });

  await client.end();
});

Configure Poku

poku.config.js:

import { defineConfig } from 'poku';
import { docker } from '@pokujs/docker';

const compose = docker.compose({ envFile: '.env.test' });

export default defineConfig({
  envFile: '.env.test',
  plugins: [
    {
      setup: () => compose.up(),
      teardown: () => compose.down(),
    },
  ],
});

tip

Configuring Poku is optional: you can orchestrate your containers however you prefer and run Poku as poku --envFile='.env.test', for example. In that case, @pokujs/docker is not needed.

Run

Add the test script to package.json:

{
  "scripts": {
    "test": "poku"
  }
}

Then run it:

npm test