let parse_args only parse, no continuation

This removes parse_args() from the call stack
It pushes down the test-mocking one level [from parse_args() to main()].
Moves parse_args into a more generic 'modules' parsing direction.

freqtrade/main.py

@@ -399,15 +399,18 @@ def cleanup() -> None:
     exit(0)
 
 
-def main() -> None:
+def main(sysargv=sys.argv[1:]) -> None:
     """
     Loads and validates the config and handles the main loop
     :return: None
     """
     global _CONF
-    args = parse_args(sys.argv[1:],
+    args = parse_args(sysargv,
                       'Simple High Frequency Trading Bot for crypto currencies')
-    if not args:
+
+    # A subcommand has been issued
+    if hasattr(args, 'func'):
+        args.func(args)
         exit(0)
 
     # Initialize logger

freqtrade/misc.py

@@ -136,14 +136,7 @@ def parse_args(args: List[str], description: str):
     )
 
     build_subcommands(parser)
-    parsed_args = parser.parse_args(args)
-
-    # No subcommand as been selected
-    if not hasattr(parsed_args, 'func'):
-        return parsed_args
-
-    parsed_args.func(parsed_args)
-    return None
+    return parser.parse_args(args)
 
 
 def build_subcommands(parser: argparse.ArgumentParser) -> None:

freqtrade/tests/test_main.py

@@ -15,6 +15,39 @@ from freqtrade.main import create_trade, handle_trade, init, \
     get_target_bid, _process, execute_sell, check_handle_timedout
 from freqtrade.misc import get_state, State
 from freqtrade.persistence import Trade
+import freqtrade.main as main
+
+
+# Test that main() can start backtesting or hyperopt.
+# and also ensure we can pass some specific arguments
+# argument parsing is done in test_misc.py
+
+def test_parse_args_backtesting(mocker):
+    backtesting_mock = mocker.patch(
+        'freqtrade.optimize.backtesting.start', MagicMock())
+    with pytest.raises(SystemExit, match=r'0'):
+        main.main(['backtesting'])
+    assert backtesting_mock.call_count == 1
+    call_args = backtesting_mock.call_args[0][0]
+    assert call_args.config == 'config.json'
+    assert call_args.live is False
+    assert call_args.loglevel == 20
+    assert call_args.subparser == 'backtesting'
+    assert call_args.func is not None
+    assert call_args.ticker_interval == 5
+
+
+def test_main_start_hyperopt(mocker):
+    hyperopt_mock = mocker.patch(
+        'freqtrade.optimize.hyperopt.start', MagicMock())
+    with pytest.raises(SystemExit, match=r'0'):
+        main.main(['hyperopt'])
+    assert hyperopt_mock.call_count == 1
+    call_args = hyperopt_mock.call_args[0][0]
+    assert call_args.config == 'config.json'
+    assert call_args.loglevel == 20
+    assert call_args.subparser == 'hyperopt'
+    assert call_args.func is not None
 
 
 def test_process_trade_creation(default_conf, ticker, limit_buy_order, health, mocker):

freqtrade/tests/test_misc.py

@@ -3,7 +3,6 @@ import json
 import time
 import argparse
 from copy import deepcopy
-from unittest.mock import MagicMock
 
 import pytest
 from jsonschema import ValidationError
@@ -101,22 +100,6 @@ def test_parse_args_dynamic_whitelist_invalid_values():
         parse_args(['--dynamic-whitelist', 'abc'], '')
 
 
-def test_parse_args_backtesting(mocker):
-    backtesting_mock = mocker.patch(
-        'freqtrade.optimize.backtesting.start', MagicMock())
-    args = parse_args(['backtesting'], '')
-    assert args is None
-    assert backtesting_mock.call_count == 1
-
-    call_args = backtesting_mock.call_args[0][0]
-    assert call_args.config == 'config.json'
-    assert call_args.live is False
-    assert call_args.loglevel == 20
-    assert call_args.subparser == 'backtesting'
-    assert call_args.func is not None
-    assert call_args.ticker_interval == 5
-
-
 def test_parse_args_backtesting_invalid():
     with pytest.raises(SystemExit, match=r'2'):
         parse_args(['backtesting --ticker-interval'], '')
@@ -125,19 +108,14 @@ def test_parse_args_backtesting_invalid():
         parse_args(['backtesting --ticker-interval', 'abc'], '')
 
 
-def test_parse_args_backtesting_custom(mocker):
-    backtesting_mock = mocker.patch(
-        'freqtrade.optimize.backtesting.start', MagicMock())
-    args = parse_args([
+def test_parse_args_backtesting_custom():
+    args = [
         '-c', 'test_conf.json',
         'backtesting',
         '--live',
         '--ticker-interval', '1',
-        '--refresh-pairs-cached'], '')
-    assert args is None
-    assert backtesting_mock.call_count == 1
-
-    call_args = backtesting_mock.call_args[0][0]
+        '--refresh-pairs-cached']
+    call_args = parse_args(args, '')
     assert call_args.config == 'test_conf.json'
     assert call_args.live is True
     assert call_args.loglevel == 20
@@ -147,28 +125,9 @@ def test_parse_args_backtesting_custom(mocker):
     assert call_args.refresh_pairs is True
 
 
-def test_parse_args_hyperopt(mocker):
-    hyperopt_mock = mocker.patch(
-        'freqtrade.optimize.hyperopt.start', MagicMock())
-    args = parse_args(['hyperopt'], '')
-    assert args is None
-    assert hyperopt_mock.call_count == 1
-
-    call_args = hyperopt_mock.call_args[0][0]
-    assert call_args.config == 'config.json'
-    assert call_args.loglevel == 20
-    assert call_args.subparser == 'hyperopt'
-    assert call_args.func is not None
-
-
 def test_parse_args_hyperopt_custom(mocker):
-    hyperopt_mock = mocker.patch(
-        'freqtrade.optimize.hyperopt.start', MagicMock())
-    args = parse_args(['-c', 'test_conf.json', 'hyperopt', '--epochs', '20'], '')
-    assert args is None
-    assert hyperopt_mock.call_count == 1
-
-    call_args = hyperopt_mock.call_args[0][0]
+    args = ['-c', 'test_conf.json', 'hyperopt', '--epochs', '20']
+    call_args = parse_args(args, '')
     assert call_args.config == 'test_conf.json'
     assert call_args.epochs == 20
     assert call_args.loglevel == 20