test: add unit tests for BlockchainInfo API edge cases and error handling

Author: galvanizze

blockapi/test/v2/api/test_blockchain_info.py

@@ -55,6 +55,46 @@ def test_parse_only():
     assert result.data[0].balance == Decimal('0.00064363')
 
 
+def test_parse_zero_balance():
+    api = BlockchainInfoApi()
+    fetch_result = FetchResult(data={'wallet': {'final_balance': 0}})
+    result = api.parse_balances(fetch_result)
+    assert result.data is None
+
+
+def test_parse_empty_wallet():
+    api = BlockchainInfoApi()
+    fetch_result = FetchResult(data={'wallet': {}})
+    result = api.parse_balances(fetch_result)
+    assert result.data is None
+
+
+def test_fetch_invalid_address(requests_mock):
+    invalid_address = 'not-a-valid-btc-address'
+    requests_mock.get(
+        'https://blockchain.info/multiaddr',
+        status_code=400,
+        reason='Bad Request',
+    )
+
+    api = BlockchainInfoApi()
+    result = api.fetch_balances(invalid_address)
+    assert result.errors == ['Bad Request']
+
+
+def test_get_balance_invalid_address_should_raise(requests_mock):
+    invalid_address = 'not-a-valid-btc-address'
+    requests_mock.get(
+        'https://blockchain.info/multiaddr',
+        status_code=400,
+        reason='Bad Request',
+    )
+
+    api = BlockchainInfoApi()
+    with pytest.raises(ApiException, match='Bad Request'):
+        api.get_balance(invalid_address)
+
+
 def test_fetch_error_response(requests_mock):
     requests_mock.get(
         'https://blockchain.info/multiaddr',

blockapi/v2/api/blockchain_info.py

@@ -35,16 +35,29 @@ def fetch_balances(self, address: str) -> FetchResult:
         )
 
     def parse_balances(self, fetch_result: FetchResult) -> ParseResult:
+        """Parse balance from blockchain.info ``/multiaddr`` response.
+
+        Note: ``final_balance`` includes **unconfirmed** transactions (0-conf)
+        and may therefore be higher than balances reported by Trezor/Blockbook
+        or Haskoin for high-activity addresses.  There is no blockchain.info
+        endpoint that reliably returns confirmed-only balance (the ``/unspent``
+        endpoint supports ``confirmations=1`` but is capped at 1 000 UTXOs
+        with broken pagination).
+        """
         if not fetch_result.data:
             return ParseResult()
 
         wallet = fetch_result.data.get('wallet', {})
         if not wallet:
             return ParseResult()
 
+        balance_raw = wallet.get('final_balance')
+        if not balance_raw:
+            return ParseResult()
+
         balances = [
             BalanceItem.from_api(
-                balance_raw=wallet.get('final_balance'),
+                balance_raw=balance_raw,
                 coin=self.coin,
                 asset_type=AssetType.AVAILABLE,
                 raw=fetch_result.data,