From d41f71bc34c961fe3075cc77071abc645461db7b Mon Sep 17 00:00:00 2001
From: gcarq <michael.egger@tsn.at>
Date: Thu, 7 Jun 2018 21:35:57 +0200
Subject: [PATCH] handle sqlalchemy NoSuchModuleError

---
 freqtrade/__init__.py               |  3 ++-
 freqtrade/main.py                   |  4 ++++
 freqtrade/persistence.py            | 12 +++++++++++-
 freqtrade/tests/test_persistence.py | 17 ++++++++++++++---
 4 files changed, 31 insertions(+), 5 deletions(-)

diff --git a/freqtrade/__init__.py b/freqtrade/__init__.py
index 37187a404..7cf0fa996 100644
--- a/freqtrade/__init__.py
+++ b/freqtrade/__init__.py
@@ -12,7 +12,8 @@ class DependencyException(BaseException):
 class OperationalException(BaseException):
     """
     Requires manual intervention.
-    This happens when an exchange returns an unexpected error during runtime.
+    This happens when an exchange returns an unexpected error during runtime
+    or given configuration is invalid.
     """
 
 
diff --git a/freqtrade/main.py b/freqtrade/main.py
index 973ed031d..81e578810 100755
--- a/freqtrade/main.py
+++ b/freqtrade/main.py
@@ -7,6 +7,7 @@ import logging
 import sys
 from typing import List
 
+from freqtrade import OperationalException
 from freqtrade.arguments import Arguments
 from freqtrade.configuration import Configuration
 from freqtrade.freqtradebot import FreqtradeBot
@@ -47,6 +48,9 @@ def main(sysargv: List[str]) -> None:
     except KeyboardInterrupt:
         logger.info('SIGINT received, aborting ...')
         return_code = 0
+    except OperationalException as e:
+        logger.error(str(e))
+        return_code = 2
     except BaseException:
         logger.exception('Fatal exception!')
     finally:
diff --git a/freqtrade/persistence.py b/freqtrade/persistence.py
index ce834bced..7fd8fdeb9 100644
--- a/freqtrade/persistence.py
+++ b/freqtrade/persistence.py
@@ -11,11 +11,14 @@ import arrow
 from sqlalchemy import (Boolean, Column, DateTime, Float, Integer, String,
                         create_engine)
 from sqlalchemy import inspect
+from sqlalchemy.exc import NoSuchModuleError
 from sqlalchemy.ext.declarative import declarative_base
 from sqlalchemy.orm.scoping import scoped_session
 from sqlalchemy.orm.session import sessionmaker
 from sqlalchemy.pool import StaticPool
 
+from freqtrade import OperationalException
+
 logger = logging.getLogger(__name__)
 
 _CONF = {}
@@ -43,7 +46,14 @@ def init(config: Dict) -> None:
             'echo': False,
         })
 
-    engine = create_engine(db_url, **kwargs)
+    try:
+        engine = create_engine(db_url, **kwargs)
+    except NoSuchModuleError:
+        error = 'Given value for db_url: \'{}\' is no valid database URL! (See {}).'.format(
+            db_url, 'http://docs.sqlalchemy.org/en/latest/core/engines.html#database-urls'
+        )
+        raise OperationalException(error)
+
     session = scoped_session(sessionmaker(bind=engine, autoflush=True, autocommit=True))
     Trade.session = session()
     Trade.query = session.query_property()
diff --git a/freqtrade/tests/test_persistence.py b/freqtrade/tests/test_persistence.py
index d8d42461b..c50ad7d2c 100644
--- a/freqtrade/tests/test_persistence.py
+++ b/freqtrade/tests/test_persistence.py
@@ -5,7 +5,7 @@ from unittest.mock import MagicMock
 import pytest
 from sqlalchemy import create_engine
 
-from freqtrade import constants
+from freqtrade import constants, OperationalException
 from freqtrade.persistence import Trade, init, clean_dry_run_db
 
 
@@ -27,13 +27,24 @@ def test_init_custom_db_url(default_conf, mocker):
     conf = deepcopy(default_conf)
 
     # Update path to a value other than default, but still in-memory
-    conf.update({'db_url': 'sqlite:////tmp/freqtrade2_test.sqlite'})
+    conf.update({'db_url': 'sqlite:///tmp/freqtrade2_test.sqlite'})
     create_engine_mock = mocker.patch('freqtrade.persistence.create_engine', MagicMock())
     mocker.patch.dict('freqtrade.persistence._CONF', conf)
 
     init(conf)
     assert create_engine_mock.call_count == 1
-    assert create_engine_mock.mock_calls[0][1][0] == 'sqlite:////tmp/freqtrade2_test.sqlite'
+    assert create_engine_mock.mock_calls[0][1][0] == 'sqlite:///tmp/freqtrade2_test.sqlite'
+
+
+def test_init_invalid_db_url(default_conf, mocker):
+    conf = deepcopy(default_conf)
+
+    # Update path to a value other than default, but still in-memory
+    conf.update({'db_url': 'unknown:///some.url'})
+    mocker.patch.dict('freqtrade.persistence._CONF', conf)
+
+    with pytest.raises(OperationalException, match=r'.*no valid database URL*'):
+        init(conf)
 
 
 def test_init_prod_db(default_conf, mocker):