public function testEvery() { $set = new Set(); $set->add('hello', 'world', 'this', 'is', 'a', 'test'); $this->assertTrue($set->every(function ($item) { return \is_string($item); })); $set->add(1); $this->assertFalse($set->every(function ($item) { return \is_string($item); })); }