add support for contextlib

dnstapir/key_resolver.py

@@ -94,6 +94,19 @@ def httpx_client(self) -> httpx.Client:
             self._httpx_client = httpx.Client()
         return self._httpx_client
 
+    def __enter__(self):
+        return self
+
+    def __exit__(self, exc_type, exc_val, exc_tb):
+        self.close()
+
     def __del__(self):
+        self.close()
+
+    def close(self):
+        """Explicitly close the client and free resources."""
         if self._httpx_client is not None:
-            self._httpx_client.close()
+            try:
+                self._httpx_client.close()
+            finally:
+                self._httpx_client = None

tests/test_key_resolver.py

@@ -15,6 +15,19 @@ def test_url_key_resolver(httpx_mock: HTTPXMock):
     httpx_mock.add_response(url=f"https://keys/{key_id}.pem", content=public_key_pem)
 
     resolver = UrlKeyResolver(client_database_base_url="https://keys")
-
     res = resolver.resolve_public_key(key_id)
     assert res == public_key
+
+
+def test_url_key_resolver_contextlib(httpx_mock: HTTPXMock):
+    key_id = "xyzzy"
+    public_key = ed25519.Ed25519PrivateKey.generate().public_key()
+    public_key_pem = public_key.public_bytes(
+        encoding=serialization.Encoding.PEM, format=serialization.PublicFormat.SubjectPublicKeyInfo
+    )
+
+    httpx_mock.add_response(url=f"https://keys/{key_id}.pem", content=public_key_pem)
+
+    with UrlKeyResolver(client_database_base_url="https://keys") as resolver:
+        res = resolver.resolve_public_key(key_id)
+        assert res == public_key