Document exception hierarchy

docs/developer.md

@@ -85,6 +85,35 @@ docker-compose exec freqtrade_develop /bin/bash
 
 ![image](https://user-images.githubusercontent.com/419355/65456522-ba671a80-de06-11e9-9598-df9ca0d8dcac.png)
 
+## ErrorHandling
+
+Freqtrade Exceptions all inherit from `FreqtradeException`.
+This general class of error should however not be used directly, instead, multiple specialized sub-Exceptions exist.
+
+Below is an outline of exception inheritance hierarchy:
+
+```
++ FreqtradeException
+|
++---+ OperationalException
+|
++---+ DependencyException
+|   |
+|   +---+ PricingError
+|   |
+|   +---+ ExchangeError
+|       |
+|       +---+ TemporaryError
+|       |
+|       +---+ DDosProtection
+|       |
+|       +---+ InvalidOrderException
+|           |
+|           +---+ RetryableOrderError
+|
++---+ StrategyError
+```
+
 ## Modules
 
 ### Dynamic Pairlist

freqtrade/exceptions.py

@@ -29,7 +29,14 @@ class PricingError(DependencyException):
     """
 
 
-class InvalidOrderException(FreqtradeException):
+class ExchangeError(DependencyException):
+    """
+    Error raised out of the exchange.
+    Has multiple Errors to determine the appropriate error.
+    """
+
+
+class InvalidOrderException(ExchangeError):
     """
     This is returned when the order is not valid. Example:
     If stoploss on exchange order is hit, then trying to cancel the order
@@ -44,13 +51,6 @@ class RetryableOrderError(InvalidOrderException):
     """
 
 
-class ExchangeError(DependencyException):
-    """
-    Error raised out of the exchange.
-    Has multiple Errors to determine the appropriate error.
-    """
-
-
 class TemporaryError(ExchangeError):
     """
     Temporary network or exchange related error.

freqtrade/freqtradebot.py

@@ -919,7 +919,7 @@ class FreqtradeBot:
                 if not trade.open_order_id:
                     continue
                 order = self.exchange.fetch_order(trade.open_order_id, trade.pair)
-            except (ExchangeError, InvalidOrderException):
+            except (ExchangeError):
                 logger.info('Cannot query order for %s due to %s', trade, traceback.format_exc())
                 continue
 
@@ -952,7 +952,7 @@ class FreqtradeBot:
         for trade in Trade.get_open_order_trades():
             try:
                 order = self.exchange.fetch_order(trade.open_order_id, trade.pair)
-            except (DependencyException, InvalidOrderException):
+            except (ExchangeError):
                 logger.info('Cannot query order for %s due to %s', trade, traceback.format_exc())
                 continue
 

freqtrade/rpc/rpc.py

@@ -11,7 +11,7 @@ from typing import Any, Dict, List, Optional, Tuple, Union
 import arrow
 from numpy import NAN, mean
 
-from freqtrade.exceptions import (ExchangeError, InvalidOrderException,
+from freqtrade.exceptions import (ExchangeError,
                                   PricingError)
 from freqtrade.exchange import timeframe_to_minutes, timeframe_to_msecs
 from freqtrade.misc import shorten_date
@@ -555,7 +555,7 @@ class RPC:
                 try:
                     self._freqtrade.exchange.cancel_order(trade.open_order_id, trade.pair)
                     c_count += 1
-                except (ExchangeError, InvalidOrderException):
+                except (ExchangeError):
                     pass
 
             # cancel stoploss on exchange ...
@@ -565,7 +565,7 @@ class RPC:
                     self._freqtrade.exchange.cancel_stoploss_order(trade.stoploss_order_id,
                                                                    trade.pair)
                     c_count += 1
-                except (ExchangeError, InvalidOrderException):
+                except (ExchangeError):
                     pass
 
             Trade.session.delete(trade)

tests/test_freqtradebot.py

@@ -1,6 +1,7 @@
 # pragma pylint: disable=missing-docstring, C0103
 # pragma pylint: disable=protected-access, too-many-lines, invalid-name, too-many-arguments
 
+from freqtrade.exchange.exchange import Exchange
 import logging
 import time
 from copy import deepcopy
@@ -4107,7 +4108,7 @@ def test_sync_wallet_dry_run(mocker, default_conf, ticker, fee, limit_buy_order,
 def test_cancel_all_open_orders(mocker, default_conf, fee, limit_buy_order, limit_sell_order):
     default_conf['cancel_open_orders_on_exit'] = True
     mocker.patch('freqtrade.exchange.Exchange.fetch_order',
-                 side_effect=[DependencyException(), limit_sell_order, limit_buy_order])
+                 side_effect=[ExchangeError(), limit_sell_order, limit_buy_order])
     buy_mock = mocker.patch('freqtrade.freqtradebot.FreqtradeBot.handle_cancel_buy')
     sell_mock = mocker.patch('freqtrade.freqtradebot.FreqtradeBot.handle_cancel_sell')