public function testFilter() { $seq = new Sequence(array(1, 2, 3)); $newSeq = $seq->filter(function ($n) { return $n === 2; }); $this->assertNotSame($newSeq, $seq); $this->assertCount(3, $seq); $this->assertCount(1, $newSeq); $this->assertSame(2, $newSeq->get(0)); }