public function testExists() { $elements = [1, 'A' => 'a', 2, 'null' => null, 3, 'A2' => 'a', 'zero' => 0]; $collection = new ArrayCollection($elements); $this->assertTrue($collection->exists(function ($key, $element) { return $key === 'A' && $element === 'a'; }), 'Element exists'); $this->assertFalse($collection->exists(function ($key, $element) { return $key === 'non-existent' && $element === 'non-existent'; }), 'Element not exists'); }