<?php

use PHPUnit\Framework\TestCase;

class Foo{}

class CollectionTypeTest extends TestCase
{
    public function testCollection() : void
    {
        $collection = [
            new Foo(),
            new Foo(),
            new Foo(),
        ];
        
        $iterator = new ArrayIterator(
            $collection
        );
        
        // assertCount/assertNotCount works on
        // Traversable too
        $this->assertNotCount(0, $collection);
        $this->assertNotCount(0, $iterator);
        
        // collection with no elements is not
        // covered by this assert
        $this->assertContainsOnlyInstancesOf('Foo', $collection);
        $this->assertContainsOnlyInstancesOf('Foo', $iterator);
    }
}

Time: 00:00.004, Memory: 18.00 MB

OK (1 test, 0 assertions)

• PHPUnit 4 Annotations
• Test your Traits in PHPUnit
• Mock objects with Prophecy in PHPUnit

PHP 8.3, Laminas MVC 3.2, Symfony 5.2, Laravel 8.28, PHPUnit 9.5, Doctrine ORM 2.8