PHP collection assert

CollectionAssertTests.php

<?php

declare(strict_types=1);

namespace App\Tests\Unit;

use LogicException;
use PHPUnit\Framework\TestCase;

class MyClass {}

class MyOtherClass {}

class CollectionAssertTests extends TestCase
{
    /** @test */
    public function works_for_an_empty_collection()
    {
        /** @var MyClass[] $collection */
        $collection = [];

        self::assertSameType($collection);
        self::assertTrue(true, 'Should NOT have thrown before!');
    }

    /** @test */
    public function works_for_a_collection_of_objects_of_the_same_type()
    {
        $collection = [
            new MyClass(),
            new MyClass(),
            new MyClass()
        ];

        self::assertSameType($collection);
        self::assertTrue(true, 'Should NOT have thrown before!');
    }

    /** @test */
    public function works_for_a_collection_of_objects_of_different_types()
    {
        $collection = [
            new MyClass(),
            new MyOtherClass()
        ];

        $this->expectException(LogicException::class);
        self::assertSameType($collection);
        self::fail('Should have thrown before!');
    }

    /** @test */
    public function works_for_a_collection_of_arrays()
    {
        /** @var MyClass[] $collection */
        $collection = [
            ['foo' => 'bar'],
            ['value' => 42]
        ];
      
        self::assertSameType($collection);
        self::assertTrue(true, 'Should NOT have thrown before!');
    }

    /** @test */
    public function works_for_a_collection_of_objects_of_same_base_class()
    {
        self::fail('Not yet implemented!');
    }

    private static function assertSameType(array $data)
    {
        $collection = array_values($data);
        $types = array_map(static function($item) {
            return get_class($item);
        }, $collection);

        if (count($types) && !(count(array_unique($types)) === 1))
        {
            throw new LogicException('Not all items in the collection are of the same type!');
        }
    }
}