feat: add option to list invoice items (#31)

Add option to list invoice items on an invoice.

Signed-off-by: Roald Nefs <info@roaldnefs.com>

Author: roaldnefs

tests/services/test_invoices.py

@@ -22,7 +22,7 @@
 import unittest
 
 from transip import TransIP
-from transip.v6.objects import Invoice
+from transip.v6.objects import Invoice, InvoiceItem
 from tests.utils import load_responses_fixtures
 
 class InvoicesTest(unittest.TestCase):
@@ -44,12 +44,24 @@ def test_list(self) -> None:
         invoices: List[Invoice] = self.client.invoices.list()  # type: ignore
         invoice: Invoice = invoices[0]
 
-        assert len(invoices) == 1
-        assert invoice.get_id() == "F0000.1911.0000.0004"  # type: ignore
+        self.assertEqual(len(invoices), 1)
+        self.assertEqual(invoice.get_id(), "F0000.1911.0000.0004")  # type: ignore
 
     @responses.activate
     def test_get(self) -> None:
         invoice_id: str = "F0000.1911.0000.0004"
         invoice: Invoice = self.client.invoices.get(invoice_id)  # type: ignore
 
-        assert invoice.get_id() == "F0000.1911.0000.0004"  # type: ignore
+        self.assertEqual(invoice.get_id(), "F0000.1911.0000.0004")  # type: ignore
+
+    @responses.activate
+    def test_items_list(self) -> None:
+        invoice: Invoice = self.client.invoices.get("F0000.1911.0000.0004")  # type: ignore
+        items: List[InvoiceItem] = invoice.items.list()  # type: ignore
+
+        self.assertEqual(len(items), 1)
+        self.assertEqual(items[0].product, "Big Storage Disk 2000 GB")  # type: ignore
+
+        # Expect the get_id() method to return None as the invoice items don't
+        # have a specific ID attribute.
+        self.assertIsNone(items[0].get_id())  # type: ignore

transip/v6/objects.py

@@ -172,10 +172,31 @@ class DomainService(CreateMixin, GetMixin, DeleteMixin, ListMixin, ApiService):
     )
 
 
+class InvoiceItem(ApiObject):
+    pass
+
+
+class InvoiceItemService(ListMixin, ApiService):
+    """Service to items of an invoice."""
+
+    _path: str = "/invoices/{parent_id}/invoice-items"
+    _obj_cls: Optional[Type[ApiObject]] = InvoiceItem
+
+    _resp_list_attr: str = "invoiceItems"
+
+
 class Invoice(ApiObject):
 
     _id_attr: str = "invoiceNumber"
 
+    @property
+    def items(self) -> InvoiceItemService:
+        """Return the service to manage the items of an invoice"""
+        return InvoiceItemService(
+            self.service.client,
+            parent=self  # type: ignore
+        )
+
 
 class InvoiceService(GetMixin, ListMixin, ApiService):