Add warning when network type is passed to BlockFrostChainContext

The Cardano ledger specification only includes two network types: testnet and mainnet, which are utilized for address encoding. However, the BlockFrostChainContext should not rely on this network type as there are additional testnets, such as preview and preprod. To enhance the flexibility, the network parameter is being deprecated and replaced by directly passing the base_url for the network to the BlockFrostChainContext constructor.

Author: cffls

pycardano/backend/blockfrost.py

@@ -1,6 +1,7 @@
 import os
 import tempfile
 import time
+import warnings
 from typing import Dict, List, Optional, Union
 
 import cbor2
@@ -40,6 +41,7 @@ class BlockFrostChainContext(ChainContext):
     Args:
         project_id (str): A BlockFrost project ID obtained from https://blockfrost.io.
         network (Network): Network to use.
+        base_url (str): Base URL for the BlockFrost API. Defaults to the preprod url.
     """
 
     api: BlockFrostApi
@@ -49,9 +51,19 @@ class BlockFrostChainContext(ChainContext):
     _protocol_param: Optional[ProtocolParameters] = None
 
     def __init__(
-        self, project_id: str, network: Network = Network.TESTNET, base_url: str = ""
+        self,
+        project_id: str,
+        network: Optional[Network] = None,
+        base_url: str = ApiUrls.preprod.value,
     ):
-        self._network = network
+        if network is not None:
+            warnings.warn(
+                "`network` argument will be deprecated in the future. Directly passing `base_url` is recommended."
+            )
+            self._network = network
+        else:
+            self._network = Network.TESTNET
+
         self._project_id = project_id
         self._base_url = (
             base_url