/**
  * try to delete a PurchaseInvoice
  */
 public function testDeletePurchaseInvoice()
 {
     $purchase = $this->_createPurchaseInvoice();
     $this->assertEquals('R-12345', $purchase['number']);
     // delete record
     $this->_json->deletePurchaseInvoices($purchase['id']);
     $this->setExpectedException('Tinebase_Exception_NotFound');
     $customerBackend = new Sales_Backend_PurchaseInvoice();
     $deletedPurchase = $customerBackend->get($purchase['id'], TRUE);
     $this->assertEquals(1, $deletedPurchase->is_deleted);
 }