add dummy file param to fix jupyter

testshell in jupyter was failing due to an extra arg.
this adds a dummy -f param, which allows TestShell to
be used in a command line or jupyter environment

Author: josibake

test/functional/test_framework/test_framework.py

@@ -194,6 +194,10 @@ def parse_args(self):
                             help="Run test using legacy wallets", dest='descriptors')
 
         self.add_options(parser)
+        # Running TestShell in a Jupyter notebook causes an additional -f argument
+        # To keep TestShell from failing with an "unrecognized argument" error, we add a dummy "-f" argument
+        # source: https://stackoverflow.com/questions/48796169/how-to-fix-ipykernel-launcher-py-error-unrecognized-arguments-in-jupyter/56349168#56349168
+        parser.add_argument("-f", "--fff", help="a dummy argument to fool ipython", default="1")
         self.options = parser.parse_args()
         self.options.previous_releases_path = previous_releases_path