public function test_permutations() { $this->assertEquals(1, Stats::permutations(1, 1)); $this->assertEquals(2, Stats::permutations(2, 1)); $this->assertEquals(12, Stats::permutations(4, 2)); $this->assertEquals(120, Stats::permutations(5, 5)); $this->assertEquals(6720, Stats::permutations(8, 5)); }