test: Set default in add_wallet_options if only one type can be chosen

Author: MacroFake

test/functional/test_framework/test_framework.py

@@ -449,11 +449,15 @@ def run_test(self):
 
     def add_wallet_options(self, parser, *, descriptors=True, legacy=True):
         group = parser.add_mutually_exclusive_group()
+        kwargs = {}
+        if descriptors + legacy == 1:
+            # If only one type can be chosen, set it as default
+            kwargs["default"] = descriptors
         if descriptors:
-            group.add_argument("--descriptors", action='store_const', const=True,
+            group.add_argument("--descriptors", action='store_const', const=True, **kwargs,
                                help="Run test using a descriptor wallet", dest='descriptors')
         if legacy:
-            group.add_argument("--legacy-wallet", action='store_const', const=False,
+            group.add_argument("--legacy-wallet", action='store_const', const=False, **kwargs,
                                help="Run test using legacy wallets", dest='descriptors')
 
     def add_nodes(self, num_nodes: int, extra_args=None, *, rpchost=None, binary=None, binary_cli=None, versions=None):