Unit Tests
Unit tests isolate a single class or function. Test one thing per test, name tests to describe behaviour, and follow Arrange-Act-Assert.
PHP
Beginner
4 min read
Writing Unit Tests
Example
class CartTest extends TestCase {
public function test_adding_item_updates_total(): void {
// Arrange
$cart = new Cart();
$item = new CartItem("Widget", 9.99, 2);
// Act
$cart->add($item);
// Assert
$this->assertSame(19.98, $cart->total());
$this->assertCount(1, $cart->items());
}
}
// Pest equivalent
it("updates total when item added", function () {
$cart = new Cart();
$cart->add(new CartItem("Widget", 9.99, 2));
expect($cart->total())->toBe(19.98);
}); Pro Tip
A test method should have one reason to fail — multiple assertions are fine if they test the same behaviour.