Add missing unit test for Arguments::testdata_dl_options()

freqtrade/arguments.py

@@ -303,28 +303,34 @@ class Arguments(object):
             '--pairs-file',
             help='File containing a list of pairs to download',
             dest='pairs_file',
-            default=None
+            default=None,
+            metavar='PATH',
         )
 
         self.parser.add_argument(
             '--export',
             help='Export files to given dir',
             dest='export',
-            default=None)
+            default=None,
+            metavar='PATH',
+        )
 
         self.parser.add_argument(
             '--days',
             help='Download data for number of days',
             dest='days',
             type=int,
-            default=None)
+            metavar='INT',
+            default=None
+        )
 
         self.parser.add_argument(
             '--exchange',
             help='Exchange name (default: %(default)s)',
             dest='exchange',
             type=str,
-            default='bittrex')
+            default='bittrex'
+        )
 
         self.parser.add_argument(
             '-t', '--timeframes',

freqtrade/tests/test_arguments.py

@@ -174,3 +174,19 @@ def test_parse_args_hyperopt_custom() -> None:
     assert call_args.subparser == 'hyperopt'
     assert call_args.spaces == ['buy']
     assert call_args.func is not None
+
+
+def test_testdata_dl_options() -> None:
+    args = [
+        '--pairs-file', 'file_with_pairs',
+        '--export', 'export/folder',
+        '--days', '30',
+        '--exchange', 'binance'
+    ]
+    arguments = Arguments(args, '')
+    arguments.testdata_dl_options()
+    args = arguments.parse_args()
+    assert args.pairs_file == 'file_with_pairs'
+    assert args.export == 'export/folder'
+    assert args.days == 30
+    assert args.exchange == 'binance'