public function testMarkPaid()
 {
     $invoice = new Invoice();
     $this->dispatcher->shouldReceive('dispatch')->once()->withAnyArgs();
     $this->dispatcher->shouldReceive('dispatch')->once()->withAnyArgs();
     // Ensure paid date is empty when creating invoice
     $this->assertNull($invoice->getPaidDate());
     $this->manager->pay($invoice);
     $this->assertInstanceOf('DateTime', $invoice->getPaidDate());
     $this->assertSame(null, $invoice->getStatus());
 }