Cannot init blockfrost chain context (#358)

* Update blockfrost.py

* Add tests

* Fix format

---------

Co-authored-by: Jerry <jerrycgh@gmail.com>

pycardano/backend/blockfrost.py

@@ -90,7 +90,7 @@ def __init__(
         )
 
         # Set network value to mainnet if base_url contains "mainnet".
-        if "mainnet" in self._base_url.value:
+        if "mainnet" in self._base_url:
             self._network = Network.MAINNET
 
         self.api = BlockFrostApi(project_id=self._project_id, base_url=self._base_url)

test/pycardano/backend/test_blockfrost.py

@@ -0,0 +1,22 @@
+from unittest.mock import MagicMock, patch
+
+from blockfrost import ApiUrls
+
+from pycardano.backend.blockfrost import BlockFrostChainContext
+from pycardano.network import Network
+
+
+@patch("pycardano.backend.blockfrost.BlockFrostApi")
+def test_blockfrost_chain_context(mock_api):
+    mock_api.return_value = MagicMock()
+    chain_context = BlockFrostChainContext("project_id", base_url=ApiUrls.mainnet.value)
+    assert chain_context.network == Network.MAINNET
+
+    chain_context = BlockFrostChainContext("project_id", base_url=ApiUrls.testnet.value)
+    assert chain_context.network == Network.TESTNET
+
+    chain_context = BlockFrostChainContext("project_id", base_url=ApiUrls.preprod.value)
+    assert chain_context.network == Network.TESTNET
+
+    chain_context = BlockFrostChainContext("project_id", base_url=ApiUrls.preview.value)
+    assert chain_context.network == Network.TESTNET