Running Tests with a Test Database

Use a separate disposable database and seed known fixtures before each integration test.

The objective is to understand the behavior and operational limits, not only the method name.

What It Does

Use a separate disposable database and seed known fixtures before each integration test.

Prerequisites

Use a dedicated development environment and sample data. Where a snippet uses an injected connection, repository, request value or mailer, supply it from your own application setup.

Example 1: Basic Use

A focused working pattern for this topic. Names such as $pdo, $authContext and $repo represent dependencies provided by the application unless initialized in the snippet.

<?php
$dsn = getenv('TEST_DB_DSN');
if (!$dsn || !str_starts_with($dsn, 'sqlite:')) throw new RuntimeException('Only test SQLite DSNs allowed');
$testDb = new PDO($dsn);
$testDb->exec('CREATE TABLE example (id INTEGER PRIMARY KEY, value TEXT)');

Example 2: A Second Scenario

A second use case that adds a different operation or data flow specific to this topic.

<?php
$db = new PDO('sqlite::memory:', null, null, [PDO::ATTR_ERRMODE => PDO::ERRMODE_EXCEPTION]);
$db->exec('CREATE TABLE customers (id INTEGER PRIMARY KEY, email TEXT UNIQUE)');
$db->prepare('INSERT INTO customers (email) VALUES (?)')->execute(['[email protected]']);
echo (int) $db->query('SELECT COUNT(*) FROM customers')->fetchColumn();

Example 3: Practical Checks

A practical validation, failure or deployment concern specific to this topic.

<?php
$db = new PDO('sqlite::memory:');
$db->exec('CREATE TABLE labels (name TEXT)');
$db->beginTransaction(); $db->prepare('INSERT INTO labels VALUES (?)')->execute(['temporary']); $db->rollBack();
assert((int) $db->query('SELECT COUNT(*) FROM labels')->fetchColumn() === 0);

Important Behavior and Edge Cases

Production credentials must never be available in the test runner; migrations and cleanup should be reproducible.

For production use, also account for error handling, data validation, resource limits and environment-specific driver behavior.

Comparison with Related Approaches

Common Beginner Mistakes

Key Takeaways

• Use a separate disposable database and seed known fixtures before each integration test.
• Production credentials must never be available in the test runner; migrations and cleanup should be reproducible.
• Use this workflow as a focused starting point rather than a substitute for application-level tests.

Choose this API or pattern when its exact semantics match your task, and verify the result against the database driver and runtime used by your application.