public function testAssertTrue()
 {
     $i = 0;
     $data = [true, true];
     $collection = new Collection($data);
     $result = $collection->assert(function ($value) use(&$i) {
         ++$i;
         return $value;
     });
     $this->assertTrue($result);
     $this->assertSame(2, $i);
 }