public function testToArrayCallsToArrayOnEachItemInCollection()
 {
     $item1 = m::mock('Collection\\Contracts\\Arrayable');
     $item1->shouldReceive('toArray')->once()->andReturn('foo.array');
     $item2 = m::mock('Collection\\Contracts\\Arrayable');
     $item2->shouldReceive('toArray')->once()->andReturn('bar.array');
     $c = new Collection([$item1, $item2]);
     $results = $c->toArray();
     $this->assertEquals(['foo.array', 'bar.array'], $results);
 }