Added check method, fails because of magic mock i think

freqtrade/exchange/exchange.py

@@ -228,6 +228,16 @@ class Exchange:
         """exchange ccxt precisionMode"""
         return self._api.precisionMode
 
+    def throw_exception_if_method_not_on_exchange(self, method_name: str):
+        """
+            Throws exception if method is implemented by the current exchange on ccxt
+            :param method_name: The method that may/may not exist for this exchange class
+        """
+        # api_method = hasattr(self._api, method_name, None)
+        if not self._api.describe()['has'][method_name]:
+            raise OperationalException(
+                f"{method_name}() has not been implemented on ccxt.{self.name}")
+
     def _log_exchange_response(self, endpoint, response) -> None:
         """ Log exchange responses """
         if self.log_responses:
@@ -361,7 +371,7 @@ class Exchange:
             raise OperationalException(
                 'Could not load markets, therefore cannot start. '
                 'Please investigate the above error for more details.'
-                )
+            )
         quote_currencies = self.get_quote_currencies()
         if stake_currency not in quote_currencies:
             raise OperationalException(

tests/exchange/test_exchange.py

@@ -2926,3 +2926,36 @@ def test_calculate_fee_rate(mocker, default_conf, order, expected) -> None:
 ])
 def test_calculate_backoff(retrycount, max_retries, expected):
     assert calculate_backoff(retrycount, max_retries) == expected
+
+
+@pytest.mark.parametrize("exchange_name,method_name,is_callable", [
+    ("binance", "set_margin_mode", True),
+    ("kraken", "set_margin_mode", False),
+    ("ftx", "set_margin_mode", False),
+    ("bittrex", "set_margin_mode", False),
+    ("binance", "not_a_real_method", False),
+    ("kraken", "not_a_real_method", False),
+    ("ftx", "not_a_real_method", False),
+    ("bittrex", "not_a_real_method", False),
+    ("binance", "create_order", True),
+    ("kraken", "create_order", True),
+    ("ftx", "create_order", True),
+    ("bittrex", "create_order", True),
+])
+def test_throw_exception_if_method_not_on_exchange(
+    mocker,
+    default_conf,
+    caplog,
+    exchange_name,
+    method_name,
+    is_callable
+):
+    exchange = get_patched_exchange(mocker, default_conf, id=exchange_name)
+    warning = f"{method_name}() has not been implemented on ccxt.{exchange_name.capitalize()}"
+    if not is_callable:
+        with pytest.raises(OperationalException) as e:
+            exchange.throw_exception_if_method_not_on_exchange(method_name)
+        assert e.value.args[0] == warning
+    else:
+        # Running the method will fail the test if an exception is thrown
+        exchange.throw_exception_if_method_not_on_exchange(method_name)