Ensure files are never leaked

Test harness warns that file descriptors are leaked and never closed.
Ensure that all files are explicitly closed (using a context decorator
whenever possible).

Author: WhyNotHugo

django_afip/models.py

@@ -486,8 +486,11 @@ def certificate_object(self) -> X509 | None:
 
         if not self.certificate:
             return None
-        self.certificate.seek(0)
-        return load_certificate(FILETYPE_PEM, self.certificate.read())
+        if not self.certificate.closed:
+            self.certificate.seek(0)
+            return load_certificate(FILETYPE_PEM, self.certificate.read())
+        with self.certificate.storage.open(self.certificate.name, "rb") as f:
+            return load_certificate(FILETYPE_PEM, f.read())
 
     def get_certificate_expiration(self) -> datetime | None:
         """Return the certificate expiration from the current certificate
@@ -541,13 +544,14 @@ def generate_csr(self, basename: str = "djangoafip") -> BinaryIO:
         systems.
         """
         csr = BytesIO()
-        crypto.create_csr(
-            self.key.file,
-            self.name,
-            f"{basename}{int(datetime.now().timestamp())}",
-            f"CUIT {self.cuit}",
-            csr,
-        )
+        with self.key.file.open("rb") as key_file:
+            crypto.create_csr(
+                key_file,
+                self.name,
+                f"{basename}{int(datetime.now().timestamp())}",
+                f"CUIT {self.cuit}",
+                csr,
+            )
         csr.seek(0)
         return csr
 
@@ -1658,6 +1662,7 @@ def save_pdf(
         if save_model:
             self.save()
 
+
 class ReceiptEntry(models.Model):
     """An entry in a receipt.
 
@@ -1712,12 +1717,12 @@ class Meta:
         constraints = (
             CheckConstraint(
                 condition=Q(discount__gte=Decimal("0.0")),
-                name="discount_positive_value"
+                name="discount_positive_value",
             ),
             CheckConstraint(
                 condition=Q(discount__lte=F("quantity") * F("unit_price")),
                 name="discount_less_than_total",
-            )
+            ),
         )
 
     def __str__(self) -> str:

tests/test_admin.py

@@ -99,7 +99,8 @@ def test_without_key(admin_client: Client) -> None:
     assertMessages(response, [Message(messages.SUCCESS, "Key generated successfully.")])
 
     taxpayer.refresh_from_db()
-    assert "-----BEGIN PRIVATE KEY-----" in taxpayer.key.file.read().decode()
+    with taxpayer.key.file.open("rb") as f:
+        assert "-----BEGIN PRIVATE KEY-----" in f.read().decode()
 
 
 def test_with_key(admin_client: Client) -> None:
@@ -119,7 +120,8 @@ def test_with_key(admin_client: Client) -> None:
     )
 
     taxpayer.refresh_from_db()
-    assert taxpayer.key.file.read().decode() == "Blah"
+    with taxpayer.key.file.open("rb") as f:
+        assert f.read().decode() == "Blah"
 
 
 def test_admin_taxpayer_request_generation_with_csr(admin_client: Client) -> None:

tests/test_taxpayer.py

@@ -15,7 +15,8 @@ def test_key_generation() -> None:
     taxpayer = factories.TaxPayerFactory.build(key=None)
     taxpayer.generate_key()
 
-    key = taxpayer.key.file.read().decode()
+    with taxpayer.key.file.open("rb") as f:
+        key = f.read().decode()
     assert key.splitlines()[0] == "-----BEGIN PRIVATE KEY-----"
     assert key.splitlines()[-1] == "-----END PRIVATE KEY-----"
 
@@ -28,7 +29,8 @@ def test_dont_overwrite_keys() -> None:
     taxpayer = factories.TaxPayerFactory.build(key=FileField(data=text))
 
     taxpayer.generate_key()
-    key = taxpayer.key.read()
+    with taxpayer.key.file.open("rb") as f:
+        key = f.read()
 
     assert text == key
 
@@ -39,7 +41,8 @@ def test_overwrite_keys_force() -> None:
     taxpayer = factories.TaxPayerFactory.build(key__data=text)
 
     taxpayer.generate_key(force=True)
-    key = taxpayer.key.file.read().decode()
+    with taxpayer.key.file.open("rb") as f:
+        key = f.read().decode()
 
     assert text != key
     assert key.splitlines()[0] == "-----BEGIN PRIVATE KEY-----"